Caffeine: Wikis

  
  
  
  

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Caffeine
Identifiers
CAS number 58-08-2 Yes check.svgY
PubChem 2519
ChemSpider 2424
EC-number 200-362-1
DrugBank DB00201
RTECS number EV6475000
SMILES
InChI
InChI key RYYVLZVUVIJVGH-UHFFFAOYAW
Properties
Molecular formula C8H10N4O2
Molar mass 194.19 g/mol
Appearance Odorless, white needles or powder
Density 1.23 g/cm3, solid
Melting point
227–228 °C (anhydrous); 234–235 °C (monohydrate)
Boiling point
178 °C subl.
Solubility in water 2.17 g/100 ml (25 °C)
18.0 g/100 ml (80 °C)
67.0 g/100 ml (100 °C)
Acidity (pKa) −0.13–1.22[1]
Dipole moment 3.64 D (calculated)
Hazards
MSDS ICSC 0405
EU Index 613-086-00-5
EU classification Harmful (Xn)
R-phrases R22
S-phrases (S2)
NFPA 704
NFPA 704.svg
0
2
0
LD50 192 mg/kg (rat, oral)[2]
 Yes check.svgY (what is this?)  (verify)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references
.Caffeine is a bitter, white crystalline xanthine alkaloid that is a psychoactive stimulant drug.^ Caffeine and ephedrine are both stimulant drugs.
  • CAFFEINE: Uses, Side Effects, Interactions and Warnings - WebMD 19 January 2010 8:49 UTC www.webmd.com [Source type: Academic]

^ Caffeine is a stimulant drug.

^ Many natural sources of caffeine also contain widely varying mixtures of other xanthine alkaloids, including the cardiac stimulants theophylline and theobromine and other substances such as polyphenols which can form insoluble complexes with caffeine.

.Caffeine was discovered by a German chemist, Friedrich Ferdinand Runge, in 1819. He coined the term kaffein, a chemical compound in coffee, which in English became caffeine.^ In 1819, the German chemist Friedrich Ferdinand Runge isolated relatively pure caffeine for the first time.

^ Armenian merchants played in role in the more modern history of coffee and this is the reason why the coffee growing region in is named the Armenia Region of Columbia.In 1819, the German chemist Friedrich Ferdinand Runge isolated relatively pure caffeine for the first time.
  • Caffeine -- History, Chemical and Physical Properties and Effects 19 January 2010 8:49 UTC www.scienceofcooking.com [Source type: Academic]

^ The water, which contains not only caffeine but also many other compounds which contribute to the flavor of coffee, is then passed through activated charcoal, which removes the caffeine.
  • Caffeine -- History, Chemical and Physical Properties and Effects 19 January 2010 8:49 UTC www.scienceofcooking.com [Source type: Academic]

[3]
.Caffeine is found in varying quantities in the beans, leaves, and fruit of some plants, where it acts as a natural pesticide that paralyzes and kills certain insects feeding on the plants.^ Caffeine is found in varying quantities in the beans, leaves, and fruit of over 60 plants, where it acts as a natural pesticide that paralyzes and kills certain insects feeding on the plants.

^ Overall, caffeine is found in the beans, leaves, and fruit of over 60 plants, where it acts as a natural pesticide that paralyzes and kills certain insects feeding upon them.
  • Caffeine -- History, Chemical and Physical Properties and Effects 19 January 2010 8:49 UTC www.scienceofcooking.com [Source type: Academic]

^ Caffeine is a plant alkaloid, found in numerous plant species, where it acts as a natural pesticide that paralyzes and kills certain insects feeding upon them.
  • Caffeine -- History, Chemical and Physical Properties and Effects 19 January 2010 8:49 UTC www.scienceofcooking.com [Source type: Academic]

.It is most commonly consumed by humans in infusions extracted from the cherries of the coffee plant and the leaves of the tea bush, as well as from various foods and drinks containing products derived from the kola nut.^ It is most commonly consumed by humans in infusions extracted from the beans of the coffee plant and the leaves of the tea bush, as well as from various foods and drinks containing products derived from the kola nut or from cacao.

^ The most commonly used caffeine-containing plants are coffee, tea, and to some extent cocoa.
  • Caffeine -- History, Chemical and Physical Properties and Effects 19 January 2010 8:49 UTC www.scienceofcooking.com [Source type: Academic]

^ The most commonly used caffeine-containing plants are coffee, tea, and to a lesser extent cocoa.

.Other sources include yerba mate, guarana berries, and the Yaupon Holly.^ Other sources include yerba mate, guarana berries, and the Yaupon Holly.

^ Other, less commonly used, sources of caffeine include the yerba mate [4] and guaraná plants, which are sometimes used in the preparation of teas and energy drinks.
  • Caffeine -- History, Chemical and Physical Properties and Effects 19 January 2010 8:49 UTC www.scienceofcooking.com [Source type: Academic]

^ It is found in the leaves and beans of the coffee plant, in tea, yerba mate, and guarana berries, and in small quantities in cocoa, the kola nut and the Yaupon Holly.
  • Caffeine -- History, Chemical and Physical Properties and Effects 19 January 2010 8:49 UTC www.scienceofcooking.com [Source type: Academic]

.In humans, caffeine is a central nervous system (CNS) stimulant, having the effect of temporarily warding off drowsiness and restoring alertness.^ In humans, caffeine is a central nervous system (CNS) stimulant, having the effect of temporarily warding off drowsiness and restoring alertness.

^ Caffeine energizes your central nervous system and stimulates improved alertness.
  • VitaDigest.com - Caffeine Extract - Caffeine Formula - Buy Cheap Caffeine Now and Save! 12 October 2009 10:29 UTC www.vitadigest.com [Source type: General]

^ Stimulant drugs interacts with CAFFEINE Stimulant drugs speed up the nervous system.
  • CAFFEINE: Uses, Side Effects, Interactions and Warnings - WebMD 19 January 2010 8:49 UTC www.webmd.com [Source type: Academic]

.Beverages containing caffeine, such as coffee, tea, soft drinks, and energy drinks, enjoy great popularity.^ Beverages containing caffeine, such as coffee, tea, soft drinks and energy drinks enjoy great popularity: caffeine is the world's most widely consumed psychoactive substance.
  • Caffeine -- History, Chemical and Physical Properties and Effects 19 January 2010 8:49 UTC www.scienceofcooking.com [Source type: Academic]

^ In foods, caffeine is used as an ingredient in soft drinks, energy drinks, and other beverages.
  • CAFFEINE: Uses, Side Effects, Interactions and Warnings - WebMD 19 January 2010 8:49 UTC www.webmd.com [Source type: Academic]

^ Preventing type 2 diabetes, when caffeine is acquired from drinking coffee or tea.
  • CAFFEINE: Uses, Side Effects, Interactions and Warnings - WebMD 19 January 2010 8:49 UTC www.webmd.com [Source type: Academic]

.Caffeine is the world's most widely consumed psychoactive substance, but, unlike many other psychoactive substances, it is legal and unregulated in nearly all jurisdictions.^ Beverages containing caffeine, such as coffee, tea, soft drinks and energy drinks enjoy great popularity; caffeine is the world's most widely consumed psychoactive substance, but unlike most other psychoactive substances, it is legal and unregulated in nearly all jurisdictions.

^ Caffeine is the most widely consumed behaviorally active substance in the world.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ Introduction Caffeine is the most widely consumed psychoactive substance in the western world.
  • Bulk Nutrition - Caffeine Description by David Tolson 19 January 2010 8:49 UTC www.bulknutrition.com [Source type: Academic]

.In North America, 90% of adults consume caffeine daily.^ In North America, 90% of adults consume some amount of caffeine daily.

^ In North America, 90% of adults consume caffeine daily.

^ It is estimated that in North America between 80 and 90 percent of adults and children habitually consume caffeine.

[4] The U.S. Food and Drug Administration lists caffeine as a "multiple purpose generally recognized as safe food substance".[5]
.Caffeine has diuretic properties, at least when administered in sufficient doses to subjects that do not have a tolerance for it.^ Following this repeated caffeine doses were administered to test the claim that repeated dosing has no extra effect on mood or performance.
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

^ Significant caffeine positive reinforcement was demonstrated in 5 of 12 subjects at one or more doses.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ In this dose-response study, we investigated the effects of blindly administered intravenous caffeine (3, 5, and 7 mg/kg) versus placebo in normal control subjects.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

[6] .Regular users, however, develop a strong tolerance to this effect,[6] and studies have generally failed to support the common notion that ordinary consumption of caffeinated beverages contributes significantly to dehydration.^ But the effect of caffeinated beverages and herbs has not been studied.
  • CAFFEINE: Uses, Side Effects, Interactions and Warnings - WebMD 19 January 2010 8:49 UTC www.webmd.com [Source type: Academic]

^ The metabolites of caffeine contribute to caffeine's effects.
  • Caffeine -- History, Chemical and Physical Properties and Effects 19 January 2010 8:49 UTC www.scienceofcooking.com [Source type: Academic]

^ The metabolites of the caffeine molecule contribute to caffeine's effects.

[7][8][9]

Contents

Occurrence

Closeup photo of brown beans
Roasted coffee beans, a common source of caffeine
.Caffeine is found in many plant species, where it acts as a natural pesticide, with high caffeine levels being reported in seedlings that are still developing foliages, but are lacking mechanical protection;[10] caffeine paralyzes and kills certain insects feeding upon the plant.^ Overall, caffeine is found in the beans, leaves, and fruit of over 60 plants, where it acts as a natural pesticide that paralyzes and kills certain insects feeding upon them.
  • Caffeine -- History, Chemical and Physical Properties and Effects 19 January 2010 8:49 UTC www.scienceofcooking.com [Source type: Academic]

^ Caffeine is a plant alkaloid, found in numerous plant species, where it acts as a natural pesticide that paralyzes and kills certain insects feeding upon them.
  • Caffeine -- History, Chemical and Physical Properties and Effects 19 January 2010 8:49 UTC www.scienceofcooking.com [Source type: Academic]

^ The LD_50 of caffeine (that is the lethal dosage reported to kill 50% of the population) is estimated by some to be 10 grams for oral administration.
  • Caffeine - Learn More about Caffeine! 19 January 2010 8:49 UTC www.a1supplements.com [Source type: Academic]

[11] .High caffeine levels have also been found in the surrounding soil of coffee bean seedlings.^ High caffeine levels have also been found in the surrounding soil of coffee bean seedlings.

^ Different varieties of coffee beans contain different levels of caffeine.
  • Caffeine Sensitivity in Coffee (INeedCoffee.com) 19 January 2010 8:49 UTC www.ineedcoffee.com [Source type: FILTERED WITH BAYES]

^ Caffeine is found in coffee, tea, cocoa beans, and kola nuts.
  • Caffeine Test Kits Caffeine Test Strips 19 January 2010 8:49 UTC www.2004dnc.com [Source type: FILTERED WITH BAYES]

.Therefore, it is understood that caffeine has a natural function as both a natural pesticide and an inhibitor of seed germination of other nearby coffee seedlings, thus giving it a better chance of survival.^ Therefore, caffeine acts as a competitive inhibitor.

^ Metabolism of caffeine and other components of coffee.
  • Caffeine for the Sustainment of Mental Task Performance: Formulations for Military Operations 19 January 2010 8:49 UTC www.nap.edu [Source type: Academic]

^ It is therefore understood that caffeine has a natural function in both a natural pesticide and as an inhibitor of seed germination of other nearby coffee seedlings[8] thus giving it a better chance of survival.

[12]
.Common sources of caffeine are coffee, tea, and to a lesser extent cocoa bean.^ The most commonly used caffeine-containing plants are coffee, tea, and to a lesser extent cocoa.

^ Caffeine is present in tea leaves and in coffee to the extent of about 4%.
  • Frequently Asked Questions about Coffee and Caffeine 19 January 2010 8:49 UTC www.indwes.edu [Source type: FILTERED WITH BAYES]

^ Green tea is a source of caffeine .
  • Caffeine | LIVESTRONG.COM 19 January 2010 8:49 UTC www.livestrong.com [Source type: General]

[13] .Less commonly used sources of caffeine include the yerba maté and guarana plants,[14] which are sometimes used in the preparation of teas and energy drinks.^ Other, less commonly used, sources of caffeine include the yerba mate [4] and guaraná plants, which are sometimes used in the preparation of teas and energy drinks.
  • Caffeine -- History, Chemical and Physical Properties and Effects 19 January 2010 8:49 UTC www.scienceofcooking.com [Source type: Academic]

^ Other, less commonly used, sources of caffeine include the yerba mate[9] and guarana plants, which are sometimes used in the preparation of teas and energy drinks.

^ Caffeine is sometimes called "theine" when it's in tea.
  • Coffee and Caffeine FAQ 15 September 2009 6:10 UTC www.nootropics.com [Source type: FILTERED WITH BAYES]
  • Frequently Asked Questions about Coffee and Caffeine 19 January 2010 8:49 UTC www.indwes.edu [Source type: FILTERED WITH BAYES]

.Two of caffeine's alternative names, mateine and guaranine, are derived from the names of these plants.^ Two of caffeine's alternative names, mateine[10] and guaranine,[11] are derived from the names of these plants.

^ Caffeine has two technical names.
  • Caffeine 19 January 2010 8:49 UTC www.herbs2000.com [Source type: FILTERED WITH BAYES]

^ Two of caffeine's alternative names, mateine [5] and guaranine , [6] are derived from the names of these plants.
  • Caffeine -- History, Chemical and Physical Properties and Effects 19 January 2010 8:49 UTC www.scienceofcooking.com [Source type: Academic]

[15][16] .Some yerba mate enthusiasts assert that mateine is a stereoisomer of caffeine, which would make it a different substance altogether.^ Some yerba mate enthusiasts assert that mateine is a stereoisomer of caffeine, which would make it a different substance altogether.

^ Caffeine induced alerting effects in various tests and differed from triazolam in some (digit substitution, drowsiness, calmness, mental slowness) but not all variables measured.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ It is possible that in addition to caffeine, there is some other substance in guarana that also produces an effect, since it 'feels' different than coffee.
  • Coffee and Caffeine FAQ 15 September 2009 6:10 UTC www.nootropics.com [Source type: FILTERED WITH BAYES]
  • Coffee and Caffeine's Frequently Asked Questions 19 January 2010 8:49 UTC www.faqs.org [Source type: FILTERED WITH BAYES]
  • Frequently Asked Questions about Coffee and Caffeine 19 January 2010 8:49 UTC www.indwes.edu [Source type: FILTERED WITH BAYES]

[14] .This is not true because caffeine is an achiral molecule, and therefore has no enantiomers; nor does it have other stereoisomers.^ However, caffeine is an achiral molecule, and therefore has no stereoisomers.

^ The Department of Chemistry at Jamaica of the University of Western Indies has made available an avi and an mpeg of a rotation of the caffeine molecule, among other molecules and chemical processes.
  • Coffee and Caffeine FAQ 15 September 2009 6:10 UTC www.nootropics.com [Source type: FILTERED WITH BAYES]
  • Coffee and Caffeine's Frequently Asked Questions 19 January 2010 8:49 UTC www.faqs.org [Source type: FILTERED WITH BAYES]
  • Frequently Asked Questions about Coffee and Caffeine 19 January 2010 8:49 UTC www.indwes.edu [Source type: FILTERED WITH BAYES]

^ Caffeine did not alter plasma MHPG in a consistent fashion and there was no correlation between changes in plasma MHPG and changes in anxiety or other ratings.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

.The disparity in experience and effects between the various natural caffeine sources could be due to the fact that plant sources of caffeine also contain widely varying mixtures of other xanthine alkaloids, including the cardiac stimulants theophylline and theobromine, and other substances such as polyphenols that can form insoluble complexes with caffeine.^ It is rich in alkaloid and contains numerous beneficial constituents including the methylxanthines along with three other distinguished compounds such as theophylline, theobromine and caffeine.
  • VitaDigest.com - Caffeine Extract - Caffeine Formula - Buy Cheap Caffeine Now and Save! 12 October 2009 10:29 UTC www.vitadigest.com [Source type: General]

^ Chocolate is a weak stimulant, which is mostly due to its content of theobromine and theophylline.
  • Caffeine -- History, Chemical and Physical Properties and Effects 19 January 2010 8:49 UTC www.scienceofcooking.com [Source type: Academic]

^ The effects of theobromine are, compared to caffeine and theophylline, relatively moderate.
  • Coffee and Caffeine FAQ 15 September 2009 6:10 UTC www.nootropics.com [Source type: FILTERED WITH BAYES]
  • Coffee and Caffeine's Frequently Asked Questions 19 January 2010 8:49 UTC www.faqs.org [Source type: FILTERED WITH BAYES]
  • Frequently Asked Questions about Coffee and Caffeine 19 January 2010 8:49 UTC www.indwes.edu [Source type: FILTERED WITH BAYES]

[17]
.One of the world's primary sources of caffeine is the coffee "bean" (which is the seed of the coffee plant), from which coffee is brewed.^ Caffeine is an alkaloid; of which there are numerous compounds such as the methylxanthines, with three distinguished compounds: caffeine, theophylline, and theobromine, found in guarana, kola nuts, coffee, tea, cocoa beans, mate and other plants.
  • Bodybuilding.com - Caffeine Information and Product Listing! Caffeine FAQ! 15 September 2009 6:10 UTC www.bodybuilding.com [Source type: FILTERED WITH BAYES]

^ I think caffeine addiction is the most common one in the world - whether you are rich or poor.
  • Sleep Disorders: Caffeine Facts 15 September 2009 6:10 UTC blogs.webmd.com [Source type: General]

^ Here's the caffeine content of Drip/Espresso/Brewed Coffee: Drip 115-175 Espresso 100 1 serving (1.5-2oz) Brewed 80-135 .
  • Frequently Asked Questions about Coffee and Caffeine 19 January 2010 8:49 UTC www.indwes.edu [Source type: FILTERED WITH BAYES]

.Caffeine content in coffee varies widely depending on the type of coffee bean and the method of preparation used;[18] even beans within a given bush can show variations in concentration.^ This association is highly variable between preparations and methods used.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ Caffeine content in coffee varies widely depending on the type of coffee bean and the method of preparation used;[13] even beans within a given bush can show variations in concentration.

^ Generally, dark-roast coffee has less caffeine than lighter roasts because the roasting process reduces the bean's caffeine content.

.In general, one serving of coffee ranges from 40 milligrams, for a single shot (30 milliliters) of arabica-variety espresso, to about 100 milligrams for a cup (120 milliliters) of drip coffee.^ This is about the amount in 1-2 cups of coffee.
  • CAFFEINE: Uses, Side Effects, Interactions and Warnings - WebMD 19 January 2010 8:49 UTC www.webmd.com [Source type: Academic]

^ Breast Exam How to Kick the Caffeine Habit A few years ago, I was drinking about one 2 liter of caffeinated soda a day in addition to four cups of coffee.
  • Caffeine Addiction - Associated Content - Topic 11 September 2009 16:016 UTC www.associatedcontent.com [Source type: General]

^ In addition, this self-report survey suggested that patients with panic disorder had an increased sensitivity to the effects of one cup of coffee.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

.In general, dark-roast coffee has less caffeine than lighter roasts because the roasting process reduces the bean's caffeine content.^ Generally, dark-roast coffee has less caffeine than lighter roasts because the roasting process reduces the bean's caffeine content.

^ H O Is it true that espresso has less caffeine than regular coffee?
  • Frequently Asked Questions about Coffee and Caffeine 19 January 2010 8:49 UTC www.indwes.edu [Source type: FILTERED WITH BAYES]

^ Is it true that espresso has less caffeine than regular coffee?
  • Coffee and Caffeine FAQ 15 September 2009 6:10 UTC www.nootropics.com [Source type: FILTERED WITH BAYES]
  • Coffee and Caffeine's Frequently Asked Questions 19 January 2010 8:49 UTC www.faqs.org [Source type: FILTERED WITH BAYES]
  • Frequently Asked Questions about Coffee and Caffeine 19 January 2010 8:49 UTC www.indwes.edu [Source type: FILTERED WITH BAYES]

[19][20] .Arabica coffee normally contains less caffeine than the robusta variety.^ H O Is it true that espresso has less caffeine than regular coffee?
  • Frequently Asked Questions about Coffee and Caffeine 19 January 2010 8:49 UTC www.indwes.edu [Source type: FILTERED WITH BAYES]

^ Is it true that espresso has less caffeine than regular coffee?
  • Coffee and Caffeine FAQ 15 September 2009 6:10 UTC www.nootropics.com [Source type: FILTERED WITH BAYES]
  • Coffee and Caffeine's Frequently Asked Questions 19 January 2010 8:49 UTC www.faqs.org [Source type: FILTERED WITH BAYES]
  • Frequently Asked Questions about Coffee and Caffeine 19 January 2010 8:49 UTC www.indwes.edu [Source type: FILTERED WITH BAYES]

^ Indeed, not less than 14% of all erstwhile consumers in Vermont had stopped the intake of all caffeine-containing beverages largely for this reason ( Hughes and Oliveto, 1997 ).
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

[18] .Coffee also contains trace amounts of theophylline, but no theobromine.^ Coffee contain caffeine and theophylline.

^ Coffee also contains trace amounts of theophylline, but no theobromine.

^ Theophylline is present only in trace amounts.
  • Frequently Asked Questions about Caffeine 15 September 2009 6:10 UTC www.sweetmarias.com [Source type: FILTERED WITH BAYES]
  • Coffee and Caffeine FAQ 15 September 2009 6:10 UTC www.nootropics.com [Source type: FILTERED WITH BAYES]
  • Coffee and Caffeine's Frequently Asked Questions 19 January 2010 8:49 UTC www.faqs.org [Source type: FILTERED WITH BAYES]
  • Frequently Asked Questions about Coffee and Caffeine 19 January 2010 8:49 UTC www.indwes.edu [Source type: FILTERED WITH BAYES]

.Tea is another common source of caffeine.^ Caffeine is present in a number of dietary sources consumed worldwide, i.e., tea, coffee, cocoa beverages, chocolate bars, and soft drinks.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ Almost all caffeine comes from dietary sources (beverages and food), most of it from coffee and tea.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ Caffeine: Sources: Coffee, tea, cola nuts, mate, guarana.
  • Coffee and Caffeine FAQ 15 September 2009 6:10 UTC www.nootropics.com [Source type: FILTERED WITH BAYES]
  • Coffee and Caffeine's Frequently Asked Questions 19 January 2010 8:49 UTC www.faqs.org [Source type: FILTERED WITH BAYES]
  • Frequently Asked Questions about Coffee and Caffeine 19 January 2010 8:49 UTC www.indwes.edu [Source type: FILTERED WITH BAYES]

.Although tea contains more caffeine than coffee, a typical serving contains much less, as tea is normally brewed much weaker.^ Arabica coffee normally contains less caffeine than the robusta variety.

^ In general, however, the dread "average" cup of coffee contains more caffeine than the "average" cup of tea.
  • The Straight Dope: Which soft drinks have the most and least caffeine? 19 January 2010 8:49 UTC www.straightdope.com [Source type: General]

^ I prefer tea to coffee, but I've heard that tea has as much caffeine as coffee.
  • Caffeine - Ask the Dietitian® 15 September 2009 6:10 UTC www.dietitian.com [Source type: FILTERED WITH BAYES]

.Besides strength of the brew, growing conditions, processing techniques- and other variables also affect caffeine content.^ The Department of Chemistry at Jamaica of the University of Western Indies has made available an avi and an mpeg of a rotation of the caffeine molecule, among other molecules and chemical processes.
  • Coffee and Caffeine FAQ 15 September 2009 6:10 UTC www.nootropics.com [Source type: FILTERED WITH BAYES]
  • Frequently Asked Questions about Coffee and Caffeine 19 January 2010 8:49 UTC www.indwes.edu [Source type: FILTERED WITH BAYES]

^ Here's the caffeine content of Drip/Espresso/Brewed Coffee: Drip 115-175 Espresso 100 1 serving (1.5-2oz) Brewed 80-135 .
  • Frequently Asked Questions about Coffee and Caffeine 19 January 2010 8:49 UTC www.indwes.edu [Source type: FILTERED WITH BAYES]

^ This suggests that other variables than caffeine are of overriding importance.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

.Certain types of tea may contain somewhat more caffeine than other teas.^ In addition to caffeine, tea contains two other alkaloids: .
  • Caffeine Caffeine Caffeine! 15 September 2009 6:10 UTC www.mindburp.com [Source type: FILTERED WITH BAYES]

^ Some people are more sensitive to caffeine than are others.
  • Caffeine — You may like caffeine's effects, but how much is too much? - MayoClinic.com 19 January 2010 8:49 UTC www.mayoclinic.com [Source type: General]

^ Tea, like coffee, contains caffeine.
  • Caffeine Caffeine Caffeine! 15 September 2009 6:10 UTC www.mindburp.com [Source type: FILTERED WITH BAYES]

.Tea contains small amounts of theobromine and slightly higher levels of theophylline than coffee.^ This level of caffeine is much lower than the amount naturally found in coffee and tea.
  • Caffeine - a knol by William Wynn 19 January 2010 8:49 UTC knol.google.com [Source type: FILTERED WITH BAYES]

^ Coffee also contains trace amounts of theophylline, but no theobromine.

^ Tea also contains two other alkaloids, theobromine and theophylline.
  • Frequently Asked Questions about Caffeine 15 September 2009 6:10 UTC www.sweetmarias.com [Source type: FILTERED WITH BAYES]
  • Coffee and Caffeine FAQ 15 September 2009 6:10 UTC www.nootropics.com [Source type: FILTERED WITH BAYES]
  • Coffee and Caffeine's Frequently Asked Questions 19 January 2010 8:49 UTC www.faqs.org [Source type: FILTERED WITH BAYES]
  • Frequently Asked Questions about Coffee and Caffeine 19 January 2010 8:49 UTC www.indwes.edu [Source type: FILTERED WITH BAYES]

.Preparation and many other factors have a significant impact on tea, and color is a very poor indicator of caffeine content.^ Preparation has a significant impact on tea, and color is a very poor indicator of caffeine content.

^ A 12-ounce (360-ml) container of Coca-Cola®, Pepsi-Cola®, Dr. Pepper®, Tab®, Mr Pibb®, Mountain Dew® and many other soft drinks contains as much caffeine as a cup of tea.
  • IS CAFFEINE A HEALTH HAZARD ? 15 September 2009 6:10 UTC www.benbest.com [Source type: Academic]

^ The brand of coffee or tea, how it is prepared, the type of beans or leaves used, and the style of serving (espresso, latte and others) also affect caffeine content.
  • Caffeine in Pregnancy - March of Dimes 19 January 2010 8:49 UTC www.marchofdimes.com [Source type: Academic]

[21] .Teas like the pale Japanese green tea gyokuro, for example, contain far more caffeine than much darker teas like lapsang souchong, which has very little.^ Caffeine is contained in Tea as well.
  • Sleep Disorders: Caffeine Facts 15 September 2009 6:10 UTC blogs.webmd.com [Source type: General]

^ Tea contains significantly more amounts of caffeine than of theophylline.
  • Coffee and Caffeine FAQ 15 September 2009 6:10 UTC www.nootropics.com [Source type: FILTERED WITH BAYES]
  • Coffee and Caffeine's Frequently Asked Questions 19 January 2010 8:49 UTC www.faqs.org [Source type: FILTERED WITH BAYES]
  • Frequently Asked Questions about Coffee and Caffeine 19 January 2010 8:49 UTC www.indwes.edu [Source type: FILTERED WITH BAYES]

^ Moderation in all caffeine containing products is the basic rule of thumb for the positive attributes without the undesireable effects of taking too much.
  • Bodybuilding.com - Caffeine Information and Product Listing! Caffeine FAQ! 15 September 2009 6:10 UTC www.bodybuilding.com [Source type: FILTERED WITH BAYES]

.
Caffeine content of select common food and drugs.^ Durrant KL. Known and hidden sources of caffeine in drug, food, and natural products.
  • CAFFEINE: Uses, Side Effects, Interactions and Warnings - WebMD 19 January 2010 8:49 UTC www.webmd.com [Source type: Academic]

^ Eating foods with high fiber content also prevents the need for caffeine induced regularity.
  • Sleep Disorders: Caffeine Facts 15 September 2009 6:10 UTC blogs.webmd.com [Source type: General]

^ There are several newsgroups in which these topics may be of relevance, including alt.drugs.caffeine, rec.food.drink.coffee, rec.food.drink.tea, and alt.food.chocolate.
  • Frequently Asked Questions about Coffee and Caffeine 19 January 2010 8:49 UTC www.indwes.edu [Source type: FILTERED WITH BAYES]

[22][23]
Product Serving size Caffeine per serving (mg) Caffeine per liter (mg)
Caffeine tablet (regular-strength) 1 tablet 100
Caffeine tablet (extra-strength) 1 tablet 200
Excedrin tablet 1 tablet 65
Hershey's Special Dark (45% cacao content) 1 bar (43 g; 1.5 oz) 31
Hershey's Milk Chocolate (11% cacao content) 1 bar (43 g; 1.5 oz) 10
Percolated coffee 207 mL (7 U.S. fl oz) 80–135 386–652
Drip coffee 207 mL (7 U.S. fl oz) 115–175 555–845
Coffee, decaffeinated 207 mL (7 U.S. fl oz) 5-15 24-72
Coffee, espresso 44–60 mL (1.5-2 U.S. fl oz) 100 1691–2254
Black tea 177 mL (6 U.S. fl oz) 50 282
Green tea 177 mL (6 U.S. fl oz) 30 169
Coca-Cola Classic 355 mL (12 U.S. fl oz) 34 96
Mountain Dew 355 mL (12 U.S. fl oz) 54.5 154
Jolt Cola 695 mL (23.5 U.S. fl oz) 280 402
Red Bull 250 mL (8.2 U.S. fl oz) 80 320
Buckfast Tonic Wine 750 mL 281.25 375
LiveWire Energy chew / fruit 1 chew 90 n/a
LiveWire Energy chew / Choc. 1 chew 100 n/a
LiveWire Energy chew / Mint Choc. 1 chew 120 n/a
.Caffeine is also a common ingredient of soft drinks such as cola, originally prepared from kola nuts.^ There is some evidence that suggests people who drink caffeinated beverages such as coffee, tea, and cola have a decreased risk of Parkinson’s disease.
  • CAFFEINE: Uses, Side Effects, Interactions and Warnings - WebMD 19 January 2010 8:49 UTC www.webmd.com [Source type: Academic]

^ I also wonder whether this is a part paid by a caffeine soft drink manufacturer mentioned.
  • Sleep Disorders: Caffeine Facts 15 September 2009 6:10 UTC blogs.webmd.com [Source type: General]

^ In foods, caffeine is used as an ingredient in soft drinks, energy drinks, and other beverages.
  • CAFFEINE: Uses, Side Effects, Interactions and Warnings - WebMD 19 January 2010 8:49 UTC www.webmd.com [Source type: Academic]

.Soft drinks typically contain about 10 to 50 milligrams of caffeine per serving.^ Soft drinks typically contain about 10 to 50 milligrams of caffeine per serving.

^ Also, energy drinks often contain caffeine.
  • Caffeine - Ask the Dietitian® 15 September 2009 6:10 UTC www.dietitian.com [Source type: FILTERED WITH BAYES]

^ In the United States, about 70% of all soft drinks consumed contain caffeine.

.By contrast, energy drinks such as Red Bull can start at 80 milligrams of caffeine per serving.^ In one case, a 36-year-old man with controlled bipolar disorder was hospitalized with symptoms of mania after drinking several cans of an energy drink containing caffeine, taurine, inositol, and other ingredients (Red Bull Energy Drink) over a period of 4 days.
  • CAFFEINE: Uses, Side Effects, Interactions and Warnings - WebMD 19 January 2010 8:49 UTC www.webmd.com [Source type: Academic]

^ As much as 80 to 300 mg of caffeine and 35 grams of processed sugar per 8-ounce serving are commonly present in energy drinks such as Cocaine, Pimp Juice, Red Bull, and Spike Shooter.
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

^ There is some evidence that suggests people who drink caffeinated beverages such as coffee, tea, and cola have a decreased risk of Parkinson’s disease.
  • CAFFEINE: Uses, Side Effects, Interactions and Warnings - WebMD 19 January 2010 8:49 UTC www.webmd.com [Source type: Academic]

.The caffeine in these drinks either originates from the ingredients used or is an additive derived from the product of decaffeination or from chemical synthesis.^ What are the dangers of these caffeine laden drinks?
  • Caffeine Addiction - Associated Content - Topic 11 September 2009 16:016 UTC www.associatedcontent.com [Source type: General]

^ The Chemistry of Caffeine and related products How much caffeine is there in [drink/food/pill]?
  • Frequently Asked Questions about Coffee and Caffeine 19 January 2010 8:49 UTC www.indwes.edu [Source type: FILTERED WITH BAYES]

^ Wemple RD, Lamb DR, McKeever KH. Caffeine vs caffeine-free sports drinks: effects on urine production at rest and during prolonged exercise.
  • CAFFEINE: Uses, Side Effects, Interactions and Warnings - WebMD 19 January 2010 8:49 UTC www.webmd.com [Source type: Academic]

.Guarana, a prime ingredient of energy drinks, contains large amounts of caffeine with small amounts of theobromine and theophylline in a naturally occurring slow-release excipient.^ Tea contains significantly more amounts of caffeine than of theophylline.
  • Coffee and Caffeine FAQ 15 September 2009 6:10 UTC www.nootropics.com [Source type: FILTERED WITH BAYES]
  • Coffee and Caffeine's Frequently Asked Questions 19 January 2010 8:49 UTC www.faqs.org [Source type: FILTERED WITH BAYES]
  • Frequently Asked Questions about Coffee and Caffeine 19 January 2010 8:49 UTC www.indwes.edu [Source type: FILTERED WITH BAYES]

^ My late teens i would have a large amount of energy drinks..
  • Sleep Disorders: Caffeine Facts 15 September 2009 6:10 UTC blogs.webmd.com [Source type: General]

^ In one case, a 36-year-old man with controlled bipolar disorder was hospitalized with symptoms of mania after drinking several cans of an energy drink containing caffeine, taurine, inositol, and other ingredients (Red Bull Energy Drink) over a period of 4 days.
  • CAFFEINE: Uses, Side Effects, Interactions and Warnings - WebMD 19 January 2010 8:49 UTC www.webmd.com [Source type: Academic]

[24]
.Chocolate derived from cocoa bean contains a small amount of caffeine.^ Three capsules were given per day, the caffeine capsules containing increasing amounts of caffeine with 100 mg at the start and 300 mg at the end of the treatment phase.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ Caffeine is present in a number of dietary sources consumed worldwide, i.e., tea, coffee, cocoa beverages, chocolate bars, and soft drinks.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ The crop contained 20 g of what appeared to be dark chocolate; a conservative estimate of the dose of methylxanthines ingested by the bird was 250 mg/kg theobromine, 20 mg/kg caffeine and 3 mg/kg theophylline.
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

.The weak stimulant effect of chocolate may be due to a combination of theobromine and theophylline as well as caffeine.^ Chocolate is a weak stimulant, which is mostly due to its content of theobromine and theophylline.
  • Caffeine -- History, Chemical and Physical Properties and Effects 19 January 2010 8:49 UTC www.scienceofcooking.com [Source type: Academic]

^ The weak stimulant effect of chocolate may be due to a combination of theobromine and theophylline as well as caffeine.

^ Chocolate contains caffeine and theobromine.
  • Caffeine: Cup of Pain, Liquid Stress | BodyTechnician.com 19 January 2010 8:49 UTC bodytechnician.com [Source type: FILTERED WITH BAYES]

[25] .A typical 28-gram serving of a milk chocolate bar has about as much caffeine as a cup of decaffeinated coffee.^ An espresso cup has about as much caffeine as a cup of dark brew.
  • Coffee and Caffeine FAQ 15 September 2009 6:10 UTC www.nootropics.com [Source type: FILTERED WITH BAYES]
  • Frequently Asked Questions about Coffee and Caffeine 19 January 2010 8:49 UTC www.indwes.edu [Source type: FILTERED WITH BAYES]

^ This is about the amount in 1-2 cups of coffee.
  • CAFFEINE: Uses, Side Effects, Interactions and Warnings - WebMD 19 January 2010 8:49 UTC www.webmd.com [Source type: Academic]

^ The majority of caffeine is produced in decaffeinating coffee.
  • Bodybuilding.com - Caffeine Information and Product Listing! Caffeine FAQ! 15 September 2009 6:10 UTC www.bodybuilding.com [Source type: FILTERED WITH BAYES]

.In recent years, various manufacturers have begun putting caffeine into shower products such as shampoo and soap, claiming that caffeine can be absorbed through the skin.^ Hypotheses concerning the penetration of substances into the skin have assumed diffusion through the lipid domains of the stratum corneum.
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

^ The quantities of caffeine found in maternal milk vary with authors, but it appears clearly that caffeine does not change maternal milk composition and has a tendency to stimule milk production.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

[26] .However, the effectiveness of such products has not been proven, and they are likely to have little stimulatory effect on the central nervous system because caffeine is not readily absorbed through the skin.^ Caffeine and the central nervous system: Mechanisms and action, biochemical, and psychostimulant effects.
  • Caffeine for the Sustainment of Mental Task Performance: Formulations for Military Operations 19 January 2010 8:49 UTC www.nap.edu [Source type: Academic]

^ Caffeine is the most widely consumed central-nervous-system stimulant.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ It is a powerful stimulant to the Central Nervous System.* Moderate use seems to be desireable by all, male and female; although excessive use can produce undesireable effects.
  • Bodybuilding.com - Caffeine Information and Product Listing! Caffeine FAQ! 15 September 2009 6:10 UTC www.bodybuilding.com [Source type: FILTERED WITH BAYES]

[27]
.Various manufacturers market caffeine tablets, claiming that using caffeine of pharmaceutical quality improves mental alertness.^ Caffeine is most commonly used to improve mental alertness, but it has many other uses.
  • CAFFEINE: Uses, Side Effects, Interactions and Warnings - WebMD 19 January 2010 8:49 UTC www.webmd.com [Source type: Academic]

^ For years athletes have been using caffeine in various doses to improve their performance.

^ Some researchers provide evidence for the withdrawal reversal hypothesis which claims that the only benefits of caffeine on mood, alertness, and mental performance are the reversal of withdrawal symptoms on habitual users [PSYCHOPHARMACOLOGY 167:54-62 (2003)].
  • IS CAFFEINE A HEALTH HAZARD ? 15 September 2009 6:10 UTC www.benbest.com [Source type: Academic]

.These effects have been borne out by research that shows that caffeine use (whether in tablet form or not) results in decreased fatigue and increased attentiveness.^ Theophylline and caffeine are two forms that have been used.
  • Caffeine versus theophylline for apnea in preterm infants 19 January 2010 8:49 UTC www.nichd.nih.gov [Source type: Academic]

^ These studies show that caffeine has a profound effect on sleep.
  • Caffeine: Psychological Effects, Use & Abuse 19 January 2010 8:49 UTC www.garynull.com [Source type: Academic]

^ The FDA looked at "studies on teratology, reproduction behavior, carcinogenicity, and cardiovascular disease...but found no evidence to show that use of caffeine (in carbonated drinks) would render these beverages injurious to health."
  • Caffeine Caffeine Caffeine! 15 September 2009 6:10 UTC www.mindburp.com [Source type: FILTERED WITH BAYES]

[28] .These tablets are commonly used by students studying for their exams and by people who work or drive for long hours.^ A cup of coffee or tea is often recommended to counter sleepiness, especially for those driving long distances or for those who need to stay up for long hours.
  • Bulk Caffeine Powder 19 January 2010 8:49 UTC purebulk.com [Source type: FILTERED WITH BAYES]

^ The positive effects that have been described in people who use caffeine include improved motor performance, decreased fatigue, enhanced sensory activity, and increased alertness.
  • caffeine (chemical compound) -- Britannica Online Encyclopedia 19 January 2010 8:49 UTC www.britannica.com [Source type: FILTERED WITH BAYES]

^ Students the world over use caffeine not only to stay awake, but also they believe the drug will improve their performance on exams.
  • Caffeine Kills: It's an Aging Drug and major cause of Stroke & Heart Attack 15 September 2009 6:10 UTC www.relfe.com [Source type: FILTERED WITH BAYES]

[29]
.Caffeine is also used pharmacologically to treat apnoea in premature newborns and as such is one of the 10 drugs most commonly given in neonatal intensive care,[30] though questions are now raised based on experimental animal research whether it might have subtle harmful side-effects.^ Caffeine is one of the most commonly used stimulants among athletes.
  • CAFFEINE: Uses, Side Effects, Interactions and Warnings - WebMD 19 January 2010 8:49 UTC www.webmd.com [Source type: Academic]

^ Studies on the side-effects of caffeine.
  • Coffee and Caffeine FAQ 15 September 2009 6:10 UTC www.nootropics.com [Source type: FILTERED WITH BAYES]
  • Coffee and Caffeine's Frequently Asked Questions 19 January 2010 8:49 UTC www.faqs.org [Source type: FILTERED WITH BAYES]
  • Frequently Asked Questions about Coffee and Caffeine 19 January 2010 8:49 UTC www.indwes.edu [Source type: FILTERED WITH BAYES]

^ An animal placed in an experimental box with two identifiable compartments can be given drugs when it is in one of the compartments.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

[30]

History

An old photo of a dozen old and middle-age men sitting on a ground around a mat. A man in front sits next to a mortar and holds a bat, ready for grinding. A man opposite to him holds a long spoon.
A coffeehouse in Palestine, circa 1900
Main articles: History of chocolate, History of coffee, Origin and history of tea
Humans have consumed caffeine since the Stone Age.[31] .Early peoples found that chewing the seeds, bark, or leaves of certain plants had the effects of easing fatigue, stimulating awareness, and elevating one's mood.^ I. Effects on mood, fatigue, cognitive performance and body temperature.
  • Caffeine for the Sustainment of Mental Task Performance: Formulations for Military Operations 19 January 2010 8:49 UTC www.nap.edu [Source type: Academic]

^ Theobromine is considerably weaker than caffeine and theophylline, having about one tenth the stimulating effect of either.
  • Coffee and Caffeine FAQ 15 September 2009 6:10 UTC www.nootropics.com [Source type: FILTERED WITH BAYES]
  • Coffee and Caffeine's Frequently Asked Questions 19 January 2010 8:49 UTC www.faqs.org [Source type: FILTERED WITH BAYES]
  • Frequently Asked Questions about Coffee and Caffeine 19 January 2010 8:49 UTC www.indwes.edu [Source type: FILTERED WITH BAYES]

^ Lieberman HR, Wurtman RJ, Emde GG, Roberts C, Coviella IL Caffeine is thought to have stimulant-like behavioral effects on mood and performance.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

.Only much later was it found that the effect of caffeine was increased by steeping such plants in hot water.^ Caffeine is an alkaloid; of which there are numerous compounds such as the methylxanthines, with three distinguished compounds: caffeine, theophylline, and theobromine, found in guarana, kola nuts, coffee, tea, cocoa beans, mate and other plants.
  • Bodybuilding.com - Caffeine Information and Product Listing! Caffeine FAQ! 15 September 2009 6:10 UTC www.bodybuilding.com [Source type: FILTERED WITH BAYES]

^ Moderation in all caffeine containing products is the basic rule of thumb for the positive attributes without the undesireable effects of taking too much.
  • Bodybuilding.com - Caffeine Information and Product Listing! Caffeine FAQ! 15 September 2009 6:10 UTC www.bodybuilding.com [Source type: FILTERED WITH BAYES]

^ One month later the effect of caffeine alone was tested.
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

.Many cultures have legends that attribute the discovery of such plants to people living many thousands of years ago.^ I cannot help but belive that there are probably many thousands of people who doing the same thing to themselves, even if it's to a less extreme degree.
  • Sleep Disorders: Caffeine Facts 15 September 2009 6:10 UTC blogs.webmd.com [Source type: General]

^ However, caffeine has not been in OTC diet pills for many years per order of the FDA, which stated that there was no evidence of efficacy for such a combination.
  • Coffee and Caffeine FAQ 15 September 2009 6:10 UTC www.nootropics.com [Source type: FILTERED WITH BAYES]
  • Frequently Asked Questions about Coffee and Caffeine 19 January 2010 8:49 UTC www.indwes.edu [Source type: FILTERED WITH BAYES]

.According to one popular Chinese legend, the Emperor of China Shennong, reputed to have reigned in about 3000 BC, accidentally discovered that when some leaves fell into boiling water, a fragrant and restorative drink resulted.^ I also discovered cutting down on my caffeine intake has cut down on any headaches I used to get when I did skip caffeine, and I feel much better subsituting water for caffeine laced drinks..
  • Sleep Disorders: Caffeine Facts 15 September 2009 6:10 UTC blogs.webmd.com [Source type: General]

^ To make coffee, you first boil water, then pour water into the container which should contain one or two spoons of coffee per cup.
  • Coffee and Caffeine FAQ 15 September 2009 6:10 UTC www.nootropics.com [Source type: FILTERED WITH BAYES]
  • Frequently Asked Questions about Coffee and Caffeine 19 January 2010 8:49 UTC www.indwes.edu [Source type: FILTERED WITH BAYES]

^ I have been drinking five cups of tea every day regularly--a tea bag soaked in a cup of boiling water, and havent suffered any adverse effects.
  • Sleep Disorders: Caffeine Facts 15 September 2009 6:10 UTC blogs.webmd.com [Source type: General]

[32][33][34] Shennong is also mentioned in Lu Yu's Cha Jing, a famous early work on the subject of tea.[35] .The history of coffee has been recorded as far back as the ninth century.^ Anecdotal reports on complaints induced by caffeine withdrawal go far back into the last century.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

.During that time, coffee beans were available only in their native habitat, Ethiopia.^ Coffee ingested during gestation induces a dose-dependent decrease in birth weight, but usually only when ingested amounts are high (i.e.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ Polycyclic aromatic hydrocarbons formed during roasting of coffee beans might partly be responsible for this effect.
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

^ During the second 3 days, the subjects had to rate six times per day their desire for coffee.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

.A popular legend traces its discovery to a goatherder named Kaldi, who apparently observed goats that became elated and sleepless at night after grazing on coffee shrubs and, upon trying the berries that the goats had been eating, experienced the same vitality.^ Caffeine enhances the action of the ergot alkaloids in the treatment of migrane, a discovery that must be credited to the sufferers from the disease who observed that strong coffee gave symptomatic relief, especially when combined with the ergot alkaloids.
  • Coffee and Caffeine FAQ 15 September 2009 6:10 UTC www.nootropics.com [Source type: FILTERED WITH BAYES]
  • Coffee and Caffeine's Frequently Asked Questions 19 January 2010 8:49 UTC www.faqs.org [Source type: FILTERED WITH BAYES]
  • Frequently Asked Questions about Coffee and Caffeine 19 January 2010 8:49 UTC www.indwes.edu [Source type: FILTERED WITH BAYES]

The earliest literary mention of coffee may be a reference to Bunchum in the works of the 9th-century Persian physician al-Razi. .In 1587, Malaye Jaziri compiled a work tracing the history and legal controversies of coffee, entitled "Undat al safwa fi hill al-qahwa". In this work, Jaziri recorded that one Sheikh, Jamal-al-Din al-Dhabhani, mufti of Aden, was the first to adopt the use of coffee in 1454, and that in the 15th century the Sufis of Yemen routinely used coffee to stay awake during prayers.^ Case in point, I was working late one night at a hotel (I was on the front desk) drinking iced coffee.
  • Sleep Disorders: Caffeine Facts 15 September 2009 6:10 UTC blogs.webmd.com [Source type: General]

^ I usually have three or four cups of coffee in the morning and another one or two cups during the day.
  • Sleep Disorders: Caffeine Facts 15 September 2009 6:10 UTC blogs.webmd.com [Source type: General]

^ Use a heaping teaspoon of very finely ground coffee and, optionally, one heaping teaspoon of sugar (to taste).
  • Coffee and Caffeine FAQ 15 September 2009 6:10 UTC www.nootropics.com [Source type: FILTERED WITH BAYES]
  • Coffee and Caffeine's Frequently Asked Questions 19 January 2010 8:49 UTC www.faqs.org [Source type: FILTERED WITH BAYES]
  • Frequently Asked Questions about Coffee and Caffeine 19 January 2010 8:49 UTC www.indwes.edu [Source type: FILTERED WITH BAYES]

.Towards the close of the 16th century, the use of coffee was recorded by a European resident in Egypt, and about this time it came into general use in the Near East.^ Use about 3oz of coffee.
  • Coffee and Caffeine FAQ 15 September 2009 6:10 UTC www.nootropics.com [Source type: FILTERED WITH BAYES]
  • Coffee and Caffeine's Frequently Asked Questions 19 January 2010 8:49 UTC www.faqs.org [Source type: FILTERED WITH BAYES]
  • Frequently Asked Questions about Coffee and Caffeine 19 January 2010 8:49 UTC www.indwes.edu [Source type: FILTERED WITH BAYES]

^ Prepare a pot of coffee at a good European strength (Miriam Nadel suggests 2 tablespoons per cup, which I'd say is about right).
  • Frequently Asked Questions about Coffee and Caffeine 19 January 2010 8:49 UTC www.indwes.edu [Source type: FILTERED WITH BAYES]

^ Google to finally give us researchers a PROXIMITY OPERATOR SUCH AS NEAR, WITH, W/10, ETC. Yes I know about using "*" and the staggernation api site.

The appreciation of coffee as a beverage in Europe, where it was first known as "Arabian wine," dates from the 17th century. .A legend states that, after the Ottoman Turks retreated from the walls of Vienna after losing a battle for the city, many sacks of coffee beans were found among their baggage.^ In many medical reports regarding asthma it states that caffienated coffee can ease asthma symptoms and can be used when you don't have access to theophylin.
  • Sleep Disorders: Caffeine Facts 15 September 2009 6:10 UTC blogs.webmd.com [Source type: General]

.Europeans did not know what to do with all the coffee beans, being unfamiliar with them.^ This FAQ is dedicated to all beverages and products that contain caffeine; including tea, coffee, chocolate, mate, caffeinated soft drinks, caffeinated pills, coffee beans, etc.
  • Frequently Asked Questions about Coffee and Caffeine 19 January 2010 8:49 UTC www.indwes.edu [Source type: FILTERED WITH BAYES]

So Franz George Kolschitzky, a Pole who had actually worked for the Turks, offered to take them. .He subsequently taught the Viennese how to make coffee, and the first coffee house in the Western world was opened in Vienna, thus starting a long tradition of coffee appreciation.^ How to make the best cup of coffee?
  • Coffee and Caffeine FAQ 15 September 2009 6:10 UTC www.nootropics.com [Source type: FILTERED WITH BAYES]
  • Coffee and Caffeine's Frequently Asked Questions 19 January 2010 8:49 UTC www.faqs.org [Source type: FILTERED WITH BAYES]
  • Frequently Asked Questions about Coffee and Caffeine 19 January 2010 8:49 UTC www.indwes.edu [Source type: FILTERED WITH BAYES]

^ How to make the best cup of coffee 7.
  • Coffee and Caffeine FAQ 15 September 2009 6:10 UTC www.nootropics.com [Source type: FILTERED WITH BAYES]
  • Coffee and Caffeine's Frequently Asked Questions 19 January 2010 8:49 UTC www.faqs.org [Source type: FILTERED WITH BAYES]

^ To make coffee, you first boil water, then pour water into the container which should contain one or two spoons of coffee per cup.
  • Coffee and Caffeine FAQ 15 September 2009 6:10 UTC www.nootropics.com [Source type: FILTERED WITH BAYES]
  • Coffee and Caffeine's Frequently Asked Questions 19 January 2010 8:49 UTC www.faqs.org [Source type: FILTERED WITH BAYES]
  • Frequently Asked Questions about Coffee and Caffeine 19 January 2010 8:49 UTC www.indwes.edu [Source type: FILTERED WITH BAYES]

[36] In Britain, the first coffee houses were opened in London in 1652, at St Michael's Alley, Cornhill. .They soon became popular throughout Western Europe, and played a significant role in social relations in the 17th and 18th centuries.^ It is believed that while hair follicles represent a weakness in the shield, they play a subordinate role in the percutaneous penetration processes.
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

[37]
.The kola nut, like the coffee berry and tea leaf, appears to have ancient origins.^ It occurs in coffee beans, tea leaves, kola nuts, cacao, maté, and guarana and in the products made from them.
  • Sleep Disorders: Caffeine Facts 15 September 2009 6:10 UTC blogs.webmd.com [Source type: General]

^ Occurs in tea, coffee, mate leaves; also in guarana paste and cola nuts: Shuman, U.S. pat.
  • Coffee and Caffeine FAQ 15 September 2009 6:10 UTC www.nootropics.com [Source type: FILTERED WITH BAYES]
  • Coffee and Caffeine's Frequently Asked Questions 19 January 2010 8:49 UTC www.faqs.org [Source type: FILTERED WITH BAYES]
  • Frequently Asked Questions about Coffee and Caffeine 19 January 2010 8:49 UTC www.indwes.edu [Source type: FILTERED WITH BAYES]

^ Almost as if obtaining these positive results from something like coffee or tea (or even nutritional supplements)is somehow "against nature" and therefore "evil."
  • Sleep Disorders: Caffeine Facts 15 September 2009 6:10 UTC blogs.webmd.com [Source type: General]

It is chewed in many West African cultures, individually or in a social setting, to restore vitality and ease hunger pangs. In 1911, kola became the focus of one of the earliest documented health scares when the US government seized 40 barrels and 20 kegs of Coca-Cola syrup in Chattanooga, Tennessee, alleging that the caffeine in its drink was "injurious to health".[38] On March 13, 1911, the government initiated United States v. .Forty Barrels and Twenty Kegs of Coca-Cola, hoping to force Coca-Cola to remove caffeine from its formula by making claims, such as that the excessive use of Coca-Cola at one girls' school led to "wild nocturnal freaks, violations of college rules and female proprieties, and even immoralities."^ It is a powerful stimulant to the Central Nervous System.* Moderate use seems to be desireable by all, male and female; although excessive use can produce undesireable effects.
  • Bodybuilding.com - Caffeine Information and Product Listing! Caffeine FAQ! 15 September 2009 6:10 UTC www.bodybuilding.com [Source type: FILTERED WITH BAYES]

^ I used to drink caffeine in my drinks but they would make me nervous and my heart would skip beats.
  • Sleep Disorders: Caffeine Facts 15 September 2009 6:10 UTC blogs.webmd.com [Source type: General]

^ From Goodman and Gilman's The Pharmacological Basis of Therapeutics: Caffeine in combination with an analgesic, such as aspirin, is widely used in the treatment of ordinary types of headache.
  • Coffee and Caffeine FAQ 15 September 2009 6:10 UTC www.nootropics.com [Source type: FILTERED WITH BAYES]
  • Coffee and Caffeine's Frequently Asked Questions 19 January 2010 8:49 UTC www.faqs.org [Source type: FILTERED WITH BAYES]

.January 2010" style="white-space:nowrap;">[citation needed] Although the judge ruled in favor of Coca-Cola, two bills were introduced to the U.S. House of Representatives in 1912 to amend the Pure Food and Drug Act, adding caffeine to the list of "habit-forming" and "deleterious" substances, which must be listed on a product's label.^ Durrant KL. Known and hidden sources of caffeine in drug, food, and natural products.
  • CAFFEINE: Uses, Side Effects, Interactions and Warnings - WebMD 19 January 2010 8:49 UTC www.webmd.com [Source type: Academic]

^ Drugs with habit-forming properties act through these same incentive-forming brain circuits ( Wise and Bozarth, 1987 ; Koob, 1992 , 1996 ).
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ However few behavioral studies have examined this substance's acute effects when administered in a range of doses that include the low doses typically found in foods and over-the-counter drugs.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

.The earliest evidence of cocoa bean use comes from residue found in an ancient Mayan pot dated to 600 BCE. In the New World, chocolate was consumed in a bitter and spicy drink called xocolatl, often seasoned with vanilla, chile pepper, and achiote.^ Safely Why I Love Rockstar Energy Drink I used to drink Starbucks coffee every day, but then I found Rockstar.
  • Caffeine Addiction - Associated Content - Topic 11 September 2009 16:016 UTC www.associatedcontent.com [Source type: General]

^ No reports were identified of negative effects associated with taurine, ginseng, and guarana used in the amounts found in most energy drinks.
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

^ One other fun note: I got a fresh vanilla bean recently and put it to good use by sealing it in an airtight container with my sugar.
  • Coffee and Caffeine FAQ 15 September 2009 6:10 UTC www.nootropics.com [Source type: FILTERED WITH BAYES]
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.Xocolatl was believed to fight fatigue, a belief that is probably attributable to the theobromine and caffeine content.^ These findings indicate that consumption of a caffeine-containing food supplement improves subjective state and cognitive performance in fatigued individuals that is likely a result of its caffeine content.
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

.Chocolate was an important luxury good throughout pre-Columbian Mesoamerica, and cocoa beans were often used as currency.^ One other fun note: I got a fresh vanilla bean recently and put it to good use by sealing it in an airtight container with my sugar.
  • Coffee and Caffeine FAQ 15 September 2009 6:10 UTC www.nootropics.com [Source type: FILTERED WITH BAYES]
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Xocolatl was introduced to Europe by the Spaniards and became a popular beverage by 1700. They also introduced the cacao tree into the West Indies and the Philippines. It was used in alchemical processes, where it was known as Black Bean.
.The leaves and stems of the Yaupon Holly (Ilex vomitoria) were used by Native Americans to brew a tea called Asi or the "black drink"[citation needed].^ Effects on blood pressure of drinking green and black tea.
  • CAFFEINE: Uses, Side Effects, Interactions and Warnings - WebMD 19 January 2010 8:49 UTC www.webmd.com [Source type: Academic]

.Archaeologists have found evidence of this use stretch back far into antiquity, possibly dating to Late Archaic times.^ Anecdotal reports on complaints induced by caffeine withdrawal go far back into the last century.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ We have found little evidence that this is a major factor in continued caffeine use.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ Been using Bing lately and finding their results half the time better than Google...

Synthesis and properties

Photo of a wide powder.
Anhydrous (dry) USP-grade caffeine
.In 1819, the German chemist Friedrich Ferdinand Runge isolated relatively pure caffeine for the first time.^ Caffeine increases energy metabolism throughout the brain but decreases at the same time cerebral blood flow, inducing a relative brain hypoperfusion.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

.According to Runge, he did this at the behest of Johann Wolfgang von Goethe.^ According to Runge, he did this at the behest of Johann Wolfgang von Goethe.

^ According to a legend, he did this at the behest of Johann Wolfgang von Goethe.
  • Caffeine -- History, Chemical and Physical Properties and Effects 19 January 2010 8:49 UTC www.scienceofcooking.com [Source type: Academic]

^ The discovery of caffeine by Runge occurred only because the famous poet Johann Wolfgang von Goethe gave Runge some mocha coffee beans as a gift, and told him to analyze them.
  • Caffeine - a knol by William Wynn 19 January 2010 8:49 UTC knol.google.com [Source type: FILTERED WITH BAYES]

[39] .In 1827, Oudry isolated "theine" from tea, but it was later proved by Mulder and Jobat that theine was the same as caffeine.^ Caffeine is sometimes called "theine" when it's in tea.
  • Coffee and Caffeine FAQ 15 September 2009 6:10 UTC www.nootropics.com [Source type: FILTERED WITH BAYES]
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^ In 1838, it was found that theine, a substance in tea, was identical to caffeine.
  • Bodybuilding.com - Caffeine Information and Product Listing! Caffeine FAQ! 15 September 2009 6:10 UTC www.bodybuilding.com [Source type: FILTERED WITH BAYES]

^ My cup or two most days just taste's good to me, I don't get a boost or the jitters, and isn't the caffeine in coffee the same as in tea?
  • Sleep Disorders: Caffeine Facts 15 September 2009 6:10 UTC blogs.webmd.com [Source type: General]

[39] .The structure of caffeine was elucidated near the end of the 19th century by Hermann Emil Fischer, who was also the first to achieve its total synthesis.^ First, I think it is safe to say that very few people who use caffeine really know the pros and cons and how to use it appropriately.
  • Sleep Disorders: Caffeine Facts 15 September 2009 6:10 UTC blogs.webmd.com [Source type: General]

^ Within days of achieving my first-ever bouts of restful sleep, I discovered that I am actually horrendously sensitive to caffeine---WHO KNEW??
  • Sleep Disorders: Caffeine Facts 15 September 2009 6:10 UTC blogs.webmd.com [Source type: General]

^ Subjects who received caffeine showed significant decreases in rCBF while the others showed no rCBF change from the first to the second measurement.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

[40] .This was part of the work for which Fischer was awarded the Nobel Prize in 1902. The nitrogen atoms are all essentially planar (in sp2 orbital hybridization), resulting in the caffeine molecule's having aromatic character.^ Results: Coffee and caffeine consumption at all 3 time points were unrelated to total miscarriage risk and the risk of loss after the interview.
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

^ Often, people who are reducing caffeine intake report being irritable, unable to work, nervous, restless, and feeling sleepy, as well as having a headache.
  • Coffee and Caffeine FAQ 15 September 2009 6:10 UTC www.nootropics.com [Source type: FILTERED WITH BAYES]
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^ Essentially similar results were obtained in a rat study where rats self-administering cocaine were treated with caffeine either as an i.p.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

.Being readily available as a byproduct of decaffeination, caffeine is not usually synthesized.^ Because coffee or caffeine-containing nutrients or drinks are widely available and culturally accepted, their consumption does not usually have negative social consequences.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ Caffeine in tablet form is readily available without a prescription at drugstores and some supermarkets throughout the country.
  • Caffeine - Recent Findings 15 September 2009 6:10 UTC druglibrary.org [Source type: FILTERED WITH BAYES]
  • Caffeine - Recent Findings 19 January 2010 8:49 UTC www.druglibrary.org [Source type: FILTERED WITH BAYES]

^ I’ve always known caffeine isn’t the best method to induce an energy boost, but I think it’s usually the easiest and most available choice.
  • caffeine : College Candy 19 January 2010 8:49 UTC collegecandy.com [Source type: General]

[41] If desired, it may be synthesized from dimethylurea and malonic acid.[42]

Pharmacology

.Global consumption of caffeine has been estimated at 120,000 tonnes per year,[43] making it the world's most popular psychoactive substance.^ Caffeine is the most widely consumed behaviorally active substance in the world.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ Introduction Caffeine is the most widely consumed psychoactive substance in the western world.
  • Bulk Nutrition - Caffeine Description by David Tolson 19 January 2010 8:49 UTC www.bulknutrition.com [Source type: Academic]

^ Caffeine consumption did not reduce dementia risk over 4 years.
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

.This number equates to one serving of a caffeine beverage for every person, per day.^ Three capsules were given per day, the caffeine capsules containing increasing amounts of caffeine with 100 mg at the start and 300 mg at the end of the treatment phase.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ The strength of the inverse association between BSP and coffee intake tended to increase with the average number of cups drunk per day.
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

^ The average caffeine consumption per day decreased from 405 mg before to 332 mg during hospitalization (P < 0.04), but the before and during hospitalization caffeine consumptions were highly correlated (rho = 0.651; P < 0.00001).
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

.Caffeine is a central nervous system and metabolic stimulant,[44] and is used both recreationally and medically to reduce physical fatigue and restore mental alertness when unusual weakness or drowsiness occurs.^ Caffeine, a central nervous system and cardiac stimulant, is frequently used by children for both academic and athletic performance enhancement.
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

^ Caffeine is the most widely consumed central-nervous-system stimulant.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ It is a powerful stimulant to the Central Nervous System.* Moderate use seems to be desireable by all, male and female; although excessive use can produce undesireable effects.
  • Bodybuilding.com - Caffeine Information and Product Listing! Caffeine FAQ! 15 September 2009 6:10 UTC www.bodybuilding.com [Source type: FILTERED WITH BAYES]

.Caffeine and other methylxanthine derivatives are also used on newborns to treat apnea and correct irregular heartbeats.^ Taking cimetidine (Tagamet) along with caffeine might increase the chance of caffeine side effects including jitteriness, headache, fast heartbeat, and others.
  • CAFFEINE: Uses, Side Effects, Interactions and Warnings - WebMD 19 January 2010 8:49 UTC www.webmd.com [Source type: Academic]

^ Caffeine use: Association with nicotine use, aggression, and other psychopathology in psychiatric and pediatric outpatient adolescents.
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

^ The responses of the patient groups regarding caffeine and carbohydrate use did not differ from each other, but all differed significantly from the responses of normal volunteers.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

.Caffeine stimulates the central nervous system first at the higher levels, resulting in increased alertness and wakefulness, faster and clearer flow of thought, increased focus, and better general body coordination, and later at the spinal cord level at higher doses.^ Caffeine is the most widely consumed central-nervous-system stimulant.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ It is a powerful stimulant to the Central Nervous System.* Moderate use seems to be desireable by all, male and female; although excessive use can produce undesireable effects.
  • Bodybuilding.com - Caffeine Information and Product Listing! Caffeine FAQ! 15 September 2009 6:10 UTC www.bodybuilding.com [Source type: FILTERED WITH BAYES]

^ Questions are raised as to what degree the physiological effects of caffeine are due to central nervous system stimulation and/or result from the release of catecholamines.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

[28] Once inside the body, it has a complex chemistry, and acts through several mechanisms as described below.

Metabolism and half-life

A diagram featuring 4 skeletal chemical formulas. <a name=.Top (caffeine) relates to similar compounds paraxanthine, theobromine and theophylline."^ Caffeine is an alkaloid; of which there are numerous compounds such as the methylxanthines, with three distinguished compounds: caffeine, theophylline, and theobromine, found in guarana, kola nuts, coffee, tea, cocoa beans, mate and other plants.
  • Bodybuilding.com - Caffeine Information and Product Listing! Caffeine FAQ! 15 September 2009 6:10 UTC www.bodybuilding.com [Source type: FILTERED WITH BAYES]

^ It is possibly relevant that demethylation of caffeine to paraxanthine in rats appears to be predominantly catalyzed by cytochrome P-450, whereas demethylation to theophylline and theobromine may also take place via flavin-containing monooxygenases ( Chung and Cha, 1997 ).
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ Theobromine is considerably weaker than caffeine and theophylline, having about one tenth the stimulating effect of either.
  • Coffee and Caffeine FAQ 15 September 2009 6:10 UTC www.nootropics.com [Source type: FILTERED WITH BAYES]
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src="http://images-mediawiki-sites.thefullwiki.org/05/2/6/5/27416173568535661.png" width="350" height="295" class="thumbimage" />
Caffeine is metabolized in the liver into three primary metabolites: paraxanthine (84%), theobromine (12%), and theophylline (4%)
.Caffeine from coffee or other beverages is absorbed by the stomach and small intestine within 45 minutes of ingestion and then distributed throughout all tissues of the body.^ Metabolism of caffeine and other components of coffee.
  • Caffeine for the Sustainment of Mental Task Performance: Formulations for Military Operations 19 January 2010 8:49 UTC www.nap.edu [Source type: Academic]

^ Coffee Recipes and other beverages.
  • Coffee and Caffeine FAQ 15 September 2009 6:10 UTC www.nootropics.com [Source type: FILTERED WITH BAYES]
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^ Coffee Recipes and other beverages 1.
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[45] It is eliminated by first-order kinetics.[46] .Caffeine can also be ingested rectally, evidenced by the formulation of suppositories of ergotamine tartrate and caffeine (for the relief of migraine)[47] and chlorobutanol and caffeine (for the treatment of hyperemesis).^ As mentioned, caffeine increases the oral and rectal absorption of ergotamine, and it is widely believed that this accounts for its enhancement of therapeutic effects.
  • Coffee and Caffeine FAQ 15 September 2009 6:10 UTC www.nootropics.com [Source type: FILTERED WITH BAYES]
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^ Caffeine is used therapeutically in combination with ergotamine for migraine headaches and in combination with nonsteroidal anti-inflammatory drugs in analgesic formulations.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ If a patient cannot tolerate ergotamine orally, rectal administration of a mixture of caffeine and ergotamine tartarate may be attempted.
  • Coffee and Caffeine FAQ 15 September 2009 6:10 UTC www.nootropics.com [Source type: FILTERED WITH BAYES]
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[48]
.The half-life of caffeine —the time required for the body to eliminate one-half of the total amount of caffeine — varies widely among individuals according to such factors as age, liver function, pregnancy, some concurrent medications, and the level of enzymes in the liver needed for caffeine metabolism.^ But for junior high students to be ingesting over two and a half times the maximum amount of caffeine recommended for adults, is irresponsible and unwise.
  • Sleep Disorders: Caffeine Facts 15 September 2009 6:10 UTC blogs.webmd.com [Source type: General]

^ My doctor told me I needed to cut down or eliminate altogether my caffeine intake, but I was too hooked to be able to do so for very long.
  • Sleep Disorders: Caffeine Facts 15 September 2009 6:10 UTC blogs.webmd.com [Source type: General]

^ Caffeine induced alerting effects in various tests and differed from triazolam in some (digit substitution, drowsiness, calmness, mental slowness) but not all variables measured.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

.In healthy adults, caffeine's half-life is approximately 4.9 hours.^ The reinforcing and subjective effects of caffeine (100 and 300 mg, PO) were determined in a group of 18 normal, healthy adults.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ There are no differences in caffeine half-life in young and elderly humans ( Blanchard and Sawers, 1983b ).
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ Poor sleepers showed significantly greater variability in caffeine Cmax, clearance had half-life, compared to normal sleepers.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

.In women taking oral contraceptives, this is increased to 5–10 hours,[49] and in pregnant women the half-life is roughly 9–11 hours.^ Caffeine levels peak 30-120 minutes after oral intake and caffeine's half-life is 3-6 hours.
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

[50] .Caffeine can accumulate in individuals with severe liver disease, increasing its half-life up to 96 hours.^ These findings suggest that, in the absence of increased blood levels, caffeine does not increase the severity of tobacco withdrawal.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ Caffeine did not increase the severity of symptoms but did decrease the severity of withdrawal-induced hunger.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ The short term consumption of caffeine may result in increased urination, gastrointestinal distress, tremors, decreased sleep, and anxiety symptoms in certain individuals.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

[51] .In infants and young children, the half-life may be longer than in adults; half-life in a newborn baby may be as long as 30 hours.^ Typically, blood pressure changes occur within 30 minutes, peak in 1-2 hours, and may persist for more than 4 hours.
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

^ However, children in general do not appear more sensitive to methylxanthine effects than adults.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ There are no differences in caffeine half-life in young and elderly humans ( Blanchard and Sawers, 1983b ).
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

.Other factors such as smoking can shorten caffeine's half-life.^ In another study ( Lane, 1996 ) it was found that the rate of smoking was higher during such periods of the day when caffeine-containing beverages were consumed than during other parts of the day.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ OBJECTIVE--To investigate the effects of smoking, alcohol, and caffeine consumption and socio-economic factors and psychosocial stress on birth weight.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ Other Formats: [Citation Format] [MEDLINE Format] Links: [203 medline neighbors] BMJ 1995 Aug 26;311(7004):531-535 Preterm delivery: effects of socioeconomic factors, psychological stress, smoking, alcohol, and caffeine.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

[52] .Fluvoxamine reduced the clearance of caffeine by 91.3%, and prolonged its elimination half-life by 11.4-fold (from 4.9 hours to 56 hours).^ Caffeine kinetics were nonlinear, with clearance significantly reduced and elimination half-life prolonged at the 500-mg compared to the 250-mg dose.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ After ingestion, caffeine is absorbed into the blood and other body tissues within 5 minutes, and peak concentration is reached in about half an hour, and the half-life is approximately 4 hours 5 .
  • Bulk Nutrition - Caffeine Description by David Tolson 19 January 2010 8:49 UTC www.bulknutrition.com [Source type: Academic]

^ There are no differences in caffeine half-life in young and elderly humans ( Blanchard and Sawers, 1983b ).
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

[53]
Caffeine is metabolized in the liver by the cytochrome P450 oxidase enzyme system (to be specific, the 1A2 isozyme) into three metabolic dimethylxanthines,[54] each of which having its own effects on the body:
.
  • Paraxanthine (84%): Has the effect of increasing lipolysis, leading to elevated glycerol and free fatty acid levels in the blood plasma.
  • Theobromine (12%): Dilates blood vessels and increases urine volume.^ Caffeine increases the level of circulating fatty acids.
    • Coffee and Caffeine FAQ 15 September 2009 6:10 UTC www.nootropics.com [Source type: FILTERED WITH BAYES]
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    ^ Theobromine, paraxanthine and the combined effects of methylxanthines.
    • Caffeine for the Sustainment of Mental Task Performance: Formulations for Military Operations 19 January 2010 8:49 UTC www.nap.edu [Source type: Academic]

    ^ Effects of black and green tea consumption on blood glucose levels in non-obese elderly men and women from Mediterranean Islands (MEDIS epidemiological study).
    • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

    .Theobromine is also the principal alkaloid in the cocoa bean, and therefore chocolate.
  • Theophylline (4%): Relaxes smooth muscles of the bronchi, and is used to treat asthma.^ Theophylline: Sources: Tea Effects: Cariac stimulant, smooth muscle relaxant, diuretic, vasodilator Theobromine: Sources: Principle alkaloid of the cocoa bean (1.5-3%) Cola nuts and tea Effects: Diuretic, smooth muscle relaxant, cardiac stimulant, vasodilator.
    • Coffee and Caffeine FAQ 15 September 2009 6:10 UTC www.nootropics.com [Source type: FILTERED WITH BAYES]
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    ^ The crop contained 20 g of what appeared to be dark chocolate; a conservative estimate of the dose of methylxanthines ingested by the bird was 250 mg/kg theobromine, 20 mg/kg caffeine and 3 mg/kg theophylline.
    • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

    ^ Tea also contains two other alkaloids, theobromine and theophylline.
    • Coffee and Caffeine FAQ 15 September 2009 6:10 UTC www.nootropics.com [Source type: FILTERED WITH BAYES]
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    The therapeutic dose of theophylline, however, is many times greater than the levels attained from caffeine metabolism.
Each of these metabolites is further metabolized and then excreted in the urine.

Mechanism of action

Two skeletal formulas: left - caffeine, right - adenosine.
Caffeine's principal mode of action is as an antagonist of adenosine receptors in the brain.
.Caffeine readily crosses the blood–brain barrier that separates the bloodstream from the interior of the brain.^ Therefore, caffeine can reduce this vasodilatation and redirect blood flow to other areas, including the brain.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ CrossRef Medline Web of Science ↵ McCall AL , Millington WR , Wurtman RJ ( 1982 ) Blood-brain barrier transport of caffeine: Dose-related restriction of adenine transport.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ Positron emission tomography (PET) was used to quantify the effect of caffeine on whole brain and regional cerebral blood flow (CBF) in humans.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

.Once in the brain, the principal mode of action is as a nonselective antagonist of adenosine receptors.^ Adenosine, adenosine receptors and the actions of caffeine.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ CrossRef Medline ↵ Holtzman SG ( 1996 ) Discriminative effects of CGS 15943, a competitive adenosine receptor antagonist, in monkeys: Comparison to methylxanthines.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ There is indeed ample evidence that caffeine (and other adenosine receptor antagonists) can increase behaviors related to dopamine.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

[55][56] .The caffeine molecule is structurally similar to adenosine, and binds to adenosine receptors on the surface of cells without activating them (an "antagonist" mechanism of action).^ Blockade of methylxanthine-sensitive adenosine receptors is the currently accepted mechanism of action of caffeine.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ Adenosine, adenosine receptors and the actions of caffeine.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ The receptors involved are similar to adenosine A 1 receptors.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

Therefore, caffeine acts as a competitive inhibitor.
.Adenosine is found in every part of the body, because it plays a role in the fundamental ATP-related energy metabolism and is necessary for RNA synthesis, but it has special functions in the brain.^ Because of the structural similarities, caffeine can slip right into adenosine receptors, keeping cyclic AMP active rather than it being broken down.* When cyclic AMP breaks down, the body's energy supply decreases.
  • Bodybuilding.com - Caffeine Information and Product Listing! Caffeine FAQ! 15 September 2009 6:10 UTC www.bodybuilding.com [Source type: FILTERED WITH BAYES]

^ Holtzman (1996) also found that the adenosine analog CGS 21680 blocked the effect of CGS 15943, indicating a role of A 2A receptors.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ Adenosine A 2A receptors are found to be concentrated in the dopamine-rich regions of the brain, irrespective of whether ligand binding or mRNA is used for the localization (Fig.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

.There is a great deal of evidence that concentrations of brain adenosine are increased by various types of metabolic stress including anoxia and ischemia.^ Caffeine increases energy metabolism throughout the brain but decreases at the same time cerebral blood flow, inducing a relative brain hypoperfusion.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ As noted above, there are adenosine A 1 receptors on virtually all types of neurons that have the ability to decrease transmitter release.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ There is evidence that methylxanthines increase the rate of firing of noradrenergic neurons in the locus ceruleus ( Grant and Redmond, 1982 ).
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

.The evidence also indicates that brain adenosine acts to protect the brain by suppressing neural activity and also by increasing blood flow through A2A and A2B receptors located on vascular smooth muscle.^ CrossRef ↵ Hauber W , Koch M ( 1997 ) Adenosine A2a receptors in the nucleus accumbens modulate prepulse inhibition of the startle response.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ Abstract / FREE Full Text ↵ Carmichael FJ , Saldivia V , Varghese GA , Israel Y , Orrego H ( 1988 ) Ethanol-induced increase in portal blood flow: Role of acetate and A1 and A2 adenosine receptors.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ It is interesting to note that a recent study ( Harvey and Lacey, 1997 ) presented strong evidence that combined dopamine D 1 and NMDA receptor stimulation increases the release of adenosine, which then acts at adenosine A 1 receptors to decrease the release of the excitatory neurotransmitter.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

[57] .By counteracting adenosine, caffeine reduces resting cerebral blood flow between 22% and 30%.^ Caffeine and cerebral blood flow.
  • Caffeine for the Sustainment of Mental Task Performance: Formulations for Military Operations 19 January 2010 8:49 UTC www.nap.edu [Source type: Academic]

^ The drug is also known to reduce cerebral blood flow (CBF).
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ Caffeine consumption, withdrawal and cerebral blood flow.
  • Caffeine for the Sustainment of Mental Task Performance: Formulations for Military Operations 19 January 2010 8:49 UTC www.nap.edu [Source type: Academic]

[58] .Caffeine also has a generally disinhibitory effect on neural activity.^ The effect of caffeine in nucleus accumbens is manifested as a decrease in activity of the cells involved, whereas the effects of cocaine and amphetamine are associated with an increased activity of the relevant cellular targets.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ CrossRef Medline Web of Science ↵ Waldeck B (1975) Effect of caffeine on locomotor activity and central catecholamine mechanisms: A study with special reference to drug interaction.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ Taken together, these data show that caffeine has rather widespread effects on cerebral functional activity in contrast to the specific effects of amphetamine and cocaine on the neural substrates believed to underlie addiction.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

.It has not been shown, however, how these effects cause increases in arousal and alertness.^ In line with these effects, caffeine intake has been associated with increased risk of heart attack 1 .
  • Bulk Nutrition - Caffeine Description by David Tolson 19 January 2010 8:49 UTC www.bulknutrition.com [Source type: Academic]

^ Objective: Previous research has shown that caffeine produces a general increase in arousal.
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

^ It is, however, less clear precisely where in the brain these effects are exerted and whether the receptors involved are A 1 receptors, A 2A receptors, or (possibly) both.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

.Adenosine is released in the brain through a complex mechanism.^ Interestingly, the mechanism appears to involve release of adenosine that acts on adenosine A 1 receptors ( Bonci and Williams, 1996 ).
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ As discussed previously ( Fredholm and Dunwiddie, 1988 ), adenosine appears to use several mechanisms in order to produce inhibition of transmitter release.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ DATA SYNTHESIS: Caffeine appears to affect blood pressure through adenosine receptor inhibition and an increased release of select neurotransmitters.
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

[57] .There is evidence that adenosine functions as a synaptically released neurotransmitter in some cases, but stress-related adenosine increases appear to be produced mainly by extracellular metabolism of ATP. It is not likely that adenosine is the primary neurotransmitter for any group of neurons, but rather that it is released together with other transmitters by a number of neuron types.^ As noted above, there are adenosine A 1 receptors on virtually all types of neurons that have the ability to decrease transmitter release.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ There is no independent evidence that this is the case.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ Extracellular ATP is very rapidly hydrolyzed to adenosine and other metabolites.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

.Unlike most neurotransmitters, adenosine does not seem to be packaged into vesicles that are released in a voltage-controlled manner, but the possibility of such a mechanism has not been completely ruled out.^ Medline ↵ Holloway FA , Modrow HE , Michaelis RC ( 1985 ) Methylxanthine discrimination in the rat: Possible benzodiazepine and adenosine mechanisms.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ DATA SYNTHESIS: Caffeine appears to affect blood pressure through adenosine receptor inhibition and an increased release of select neurotransmitters.
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

^ It does interact with the dopaminergic transmission, but the mechanism is very different from that of other drugs such as cocaine and amphetamine.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

.Several classes of adenosine receptors have been described, with different anatomical distributions.^ Medline ↵ Fastbom J , Pazos A , Palacios JM ( 1987 ) The distribution of adenosine A1 receptors and 5 ′ -nucleotidase in the brain of some commonly used experimental animals.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ Jacobson KA , von Lubitz DK , Daly JW , Fredholm BB ( 1996 ) Adenosine receptor ligands: Differences with acute versus chronic treatment.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ Probably adenosine A 1 and A 2A receptors are involved in producing the sleep-promoting effects of adenosine, but these effects appear to be exerted in different parts of the brain.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

.A1 receptors are widely distributed, and act to inhibit calcium uptake.^ It is further assumed that the rate of cyclic AMP production is importantly controlled by adenosine, acting on A 2A receptors to stimulate adenylyl cyclase, and by dopamine, acting on D 2 receptors to inhibit the enzyme.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ Dopamine acts on two classes of receptors: D 1 -like (D 1 and D 5 ) and D 2 -like (D 2 , D 3 , D 4 ), which differ in their G-protein coupling and distribution in the brain (see Jaber et al., 1996 ).
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

.A2A receptors are heavily concentrated in the basal ganglia, an area that plays a critical role in behavior control, but can be found in other parts of the brain as well, in lower densities.^ There is indeed ample evidence that caffeine (and other adenosine receptor antagonists) can increase behaviors related to dopamine.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ Therefore, caffeine can reduce this vasodilatation and redirect blood flow to other areas, including the brain.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ Holtzman (1996) also found that the adenosine analog CGS 21680 blocked the effect of CGS 15943, indicating a role of A 2A receptors.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

.There is evidence that A 2A receptors interact with the dopamine system, which is involved in reward and arousal.^ Opiates also interact with the mesolimbic dopamine system.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ There is evidence that these interactions between adenosine A 2A and dopamine D 2 receptors observed in vitro have functional correlates in intact striatum.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ There is indeed ample evidence that caffeine (and other adenosine receptor antagonists) can increase behaviors related to dopamine.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

(A2A receptors can also be found on arterial walls and blood cell membranes.)
.Beyond its general neuroprotective effects, there are reasons to believe that adenosine may be more specifically involved in control of the sleep-wake cycle.^ There is a link between adenosine and the sleep-wake cycle in rodents.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ Because dopamine and noradrenaline neurons also are involved in arousal, there is ample neuropharmacological basis for assuming that central stimulatory effect of caffeine could be related to inhibition of adenosine A 1 receptors.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ This effect appears to be quite general and is due to an activation of potassium channels via adenosine A 1 receptors ( Dunwiddie, 1985 ).
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

.Robert McCarley and his colleagues have argued that accumulation of adenosine may be a primary cause of the sensation of sleepiness that follows prolonged mental activity, and that the effects may be mediated both by inhibition of wake-promoting neurons via A1 receptors, and activation of sleep-promoting neurons via indirect effects on A2A receptors.^ Adenosine A 2A receptors are coupled to G-proteins that activate adenylyl cyclase.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ Adenosine: A mediator of the sleep-inducing effects of prolonged wakefulness.
  • Caffeine for the Sustainment of Mental Task Performance: Formulations for Military Operations 19 January 2010 8:49 UTC www.nap.edu [Source type: Academic]

^ A 1 and A 2A receptors are both G-protein-coupled.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

[59] .More recent studies have provided additional evidence for the importance of A2A, but not A1, receptors.^ It is interesting to note that a recent study ( Harvey and Lacey, 1997 ) presented strong evidence that combined dopamine D 1 and NMDA receptor stimulation increases the release of adenosine, which then acts at adenosine A 1 receptors to decrease the release of the excitatory neurotransmitter.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ This study provides the clearest evidence to date of complete tolerance development to a CNS effect of caffeine in humans.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ When this radioligand is used there is little evidence for significant A 2A receptor binding outside striatum, nucleus accumbens, and tuberculum olfactorium.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

[60]
.Some of the secondary effects of caffeine are probably caused by actions unrelated to adenosine.^ Adenosine, adenosine receptors and the actions of caffeine.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ Secondary analyses of data collected after a day of normal caffeine consumption were also carried out to examine some alternative explanations of their results which showed effects of caffeine after a day of normal caffeine consumption.
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

^ The effects of caffeine on learning, memory, performance and coordination are rather related to the methylxanthine action on arousal, vigilance and fatigue.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

Like other methylated xanthines, caffeine is both a
.
  1. competitive nonselective phosphodiesterase inhibitor [61] which raises intracellular cAMP, activates PKA, inhibits TNF-alpha [62][63] and leukotriene [64] synthesis, and reduces inflammation and innate immunity [64].^ When caffeine was added together with NCS to the culture of HeLa-S3 cells, NCS-induced inhibition of DNA synthesis and of mitosis was markedly reduced in the presence of caffeine.
    • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

    ^ Background: Clopidogrel inhibits the platelet P2Y12 receptor, leading to increased intracellular cyclic AMP (CAMP) levels.
    • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

    ^ Caffeine 1,3,7-trimethylxanthine Theophylline 1,3-dimethylxanthine Theobromine 3,7-dimethylxanthine Coffee and tea contain caffeine and theophylline, respectively, which are methylated purine derivatives that inhibit cAMP phosphodiesterase.
    • Coffee and Caffeine FAQ 15 September 2009 6:10 UTC www.nootropics.com [Source type: FILTERED WITH BAYES]
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    .Caffeine is also added to agar, which partially inhibits the growth of Saccharomyces cerevisiae by inhibiting cyclic AMP phosphodiesterase.^ When caffeine was added together with NCS to the culture of HeLa-S3 cells, NCS-induced inhibition of DNA synthesis and of mitosis was markedly reduced in the presence of caffeine.
    • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

    ^ Background: Clopidogrel inhibits the platelet P2Y12 receptor, leading to increased intracellular cyclic AMP (CAMP) levels.
    • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

    ^ Sublethal effects measured for caffeine exposure included impaired C. dubia reproduction (IC50 = 44 mg/L) and inhibited P. promelas growth (IC50 = 71 mg/L).
    • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

    [65]
  2. nonselective adenosine receptor antagonist [56] (see above).
.Phosphodiesterase inhibitors inhibit cAMP-phosphodiesterase (cAMP-PDE) enzymes, which convert cyclic AMP (cAMP) in cells to its noncyclic form, thus allowing cAMP to build up in cells.^ Background: Clopidogrel inhibits the platelet P2Y12 receptor, leading to increased intracellular cyclic AMP (CAMP) levels.
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

^ On the other hand, when the level of l -homocysteine is raised, it can trap adenosine formed via AMP breakdown as S -adenosylhomocysteine inside the cell.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ CrossRef Medline ↵ Smellie FW , Davis CW , Daly JW , Wells JN ( 1979 ) Alkylxanthines: Inhibition of adenosine-elicited accumulation of cyclic AMP in brain slices and of brain phosphodiesterase activity.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

.Cyclic AMP participates in activation of protein kinase A (PKA) to begin the phosphorylation of specific enzymes used in glucose synthesis.^ Because caffeine fools the body into using enzymes to break it down instead, the cyclic AMP supply remains higher for longer.* I bet you always wanted to know that.
  • Bodybuilding.com - Caffeine Information and Product Listing! Caffeine FAQ! 15 September 2009 6:10 UTC www.bodybuilding.com [Source type: FILTERED WITH BAYES]

^ It is further assumed that the rate of cyclic AMP production is importantly controlled by adenosine, acting on A 2A receptors to stimulate adenylyl cyclase, and by dopamine, acting on D 2 receptors to inhibit the enzyme.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ Cyclic AMP response element-binding protein (CREB) is a likely candidate.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

.By blocking its removal, caffeine intensifies and prolongs the effects of epinephrine and epinephrine-like drugs such as amphetamine, methamphetamine, and methylphenidate.^ In some studies, the effects of caffeine are even weaker in this regard than those of nicotine, which is notoriously unreliable as a reinforcing drug.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ However, also a dose of caffeine taken in the morning can have such effects the following night ( Landolt et al., 1995b ).
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ Finally, we will briefly comment upon the similarities and dissimilarities between caffeine and known addictive drugs such as cocaine, morphine, and nicotine.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

.Increased concentrations of cAMP in parietal cells causes an increased activation of protein kinase A (PKA), which in turn increases activation of H+/K+ ATPase, resulting finally in increased gastric acid secretion by the cell.^ We turn now to the question of whether there are adenosine receptors that are activated not only by the high adenosine levels seen in ischemia, but also by the low (high nanomolar concentrations) physiological levels.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ Caffeine causes a concentration-dependent increase in c- fos expression, which is confined to the striatum ( Johansson et al., 1994 ).
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ Because activation of adenosine A 1 receptors is known to cause a decrease in cAMP formation, it is conceivable that this may also be a mechanism of decreased transmitter release—at least under some circumstances.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

.Cyclic AMP also increases the activity of the funny current, which directly increases heart rate.^ Background: Clopidogrel inhibits the platelet P2Y12 receptor, leading to increased intracellular cyclic AMP (CAMP) levels.
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

^ Significantly greater increases in forearm blood flow and heart rate during mental arithmetic on the caffeine day suggested a potentiation of sympathetic, beta-adrenergic activity.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ Results: Nicotine increased heart rate and subjective ratings indicative of aversive effects, and decreased reaction times.
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

.Caffeine is also a structural analogue of strychnine and, like it (though much less potent), a competitive antagonist at ionotropic glycine receptors.^ CrossRef Medline ↵ Holtzman SG ( 1996 ) Discriminative effects of CGS 15943, a competitive adenosine receptor antagonist, in monkeys: Comparison to methylxanthines.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ There is indeed ample evidence that caffeine (and other adenosine receptor antagonists) can increase behaviors related to dopamine.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ This effect of caffeine could be partly mimicked by DPCPX, an adenosine A 1 receptor antagonist, but not by the A 2A receptor antagonist SCH 58261.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

[66]
.Metabolites of caffeine also contribute to caffeine's effects.^ Effects of caffeine on the vasculature may contribute to the relief of some headaches and in postprandial hypotension.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ The effect of caffeine is shared by some other xanthines, including its metabolites theophylline and paraxanthine ( Fredholm et al., 1976 ; Garrett and Holtzman, 1995 ).
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

.Paraxanthine is responsible for an increase in the lipolysis process, which releases glycerol and fatty acids into the blood to be used as a source of fuel by the muscles.^ DATA SYNTHESIS: Caffeine appears to affect blood pressure through adenosine receptor inhibition and an increased release of select neurotransmitters.
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

^ CONCLUSIONS: Blood pressure and plasma glucose increased post-exercise with DS use, which could be detrimental in some people.
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

^ Caffeine increases the level of circulating fatty acids.
  • Coffee and Caffeine FAQ 15 September 2009 6:10 UTC www.nootropics.com [Source type: FILTERED WITH BAYES]
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.Theobromine is a vasodilator that increases the amount of oxygen and nutrient flow to the brain and muscles.^ However, these changes are moderate and the decrease in blood flow could be compensated for by an increase in oxygen and glucose extraction, because the consumption of moderate amounts of caffeine has positive effects on alertness.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ Caffeine increases energy metabolism throughout the brain but decreases at the same time cerebral blood flow, inducing a relative brain hypoperfusion.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

.Theophylline acts as a smooth muscle relaxant that chiefly affects bronchioles and acts as a chronotrope and inotrope that increases heart rate and efficiency.^ Theophylline: Sources: Tea Effects: Cariac stimulant, smooth muscle relaxant, diuretic, vasodilator Theobromine: Sources: Principle alkaloid of the cocoa bean (1.5-3%) Cola nuts and tea Effects: Diuretic, smooth muscle relaxant, cardiac stimulant, vasodilator.
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^ On humans caffeine acts particularly on the brain and skeletal muscles while theophylline targets heart, bronchia, and kidneys.
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^ Results: Nicotine increased heart rate and subjective ratings indicative of aversive effects, and decreased reaction times.
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

[67]
Top: picture of a regular spider web with a caption "drug-naive", bottom: heavily distorted spider web with a caption "caffeinated".
Caffeine has a significant effect on spiders, which is reflected in the construction of their webs.

Effects when taken in moderation

Torso of a young man with overlayed text of main side-effects of caffeine.
.
Overview of the more common side-effects of caffeine, possibly appearing even at levels below overdose.
^ Studies on the side-effects of caffeine.
  • Coffee and Caffeine FAQ 15 September 2009 6:10 UTC www.nootropics.com [Source type: FILTERED WITH BAYES]
  • Coffee and Caffeine's Frequently Asked Questions 19 January 2010 8:49 UTC www.faqs.org [Source type: FILTERED WITH BAYES]
  • Frequently Asked Questions about Coffee and Caffeine 19 January 2010 8:49 UTC www.indwes.edu [Source type: FILTERED WITH BAYES]

^ Few side effects associated with taking caffeine during exercise were reported.
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

^ It was found that researchers have generally failed to take account of the fact that habitual use of caffeine, even at moderate levels, leads to physical dependence evidenced by physiological, behavioural and subjective withdrawal effects during periods of abstinence.
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

[68]
.The precise amount of caffeine necessary to produce effects varies from person to person depending on body size and degree of tolerance to caffeine.^ This study provides the clearest evidence to date of complete tolerance development to a CNS effect of caffeine in humans.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ The effects of caffeine and smoking on cognitive performance, subjective variables, heart rate, and EEG were assessed in two sessions.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ The central nervous system does not seem to develop a great tolerance to the effects of caffeine although dependence and withdrawal symptoms are reported.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

.It takes less than an hour for caffeine to begin affecting the body and a mild dose wears off in three to four hours.^ Indeed, not less than 14% of all erstwhile consumers in Vermont had stopped the intake of all caffeine-containing beverages largely for this reason ( Hughes and Oliveto, 1997 ).
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ We found reduced saccadic interruptions as a result of caffeine ingestion compared with placebo (p less than .05).
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ Children reported feeling significantly less "sluggish" after caffeine ingestion than after placebo ingestion.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

[28] .Consumption of caffeine does not eliminate the need for sleep, it only temporarily reduces the sensation of being tired throughout the day.^ Influence of alcohol and caffeine consumption on caffeine elimination.
  • Caffeine for the Sustainment of Mental Task Performance: Formulations for Military Operations 19 January 2010 8:49 UTC www.nap.edu [Source type: Academic]

^ Regular caffeine consumption reduces sensitivity to caffeine.
  • Coffee and Caffeine's Frequently Asked Questions 19 January 2010 8:49 UTC www.faqs.org [Source type: FILTERED WITH BAYES]
  • Frequently Asked Questions about Coffee and Caffeine 19 January 2010 8:49 UTC www.indwes.edu [Source type: FILTERED WITH BAYES]

^ Secondary analyses of data collected after a day of normal caffeine consumption were also carried out to examine some alternative explanations of their results which showed effects of caffeine after a day of normal caffeine consumption.
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

.In general, 25 to 50 milligrams of caffeine is sufficient for most people to report increased alertness and arousal as well as subjectively lower levels of fatigue.^ Influence of caffeine on selective attention in well-rested and fatigued subjects.
  • Caffeine for the Sustainment of Mental Task Performance: Formulations for Military Operations 19 January 2010 8:49 UTC www.nap.edu [Source type: Academic]

^ Caffeine increases anxiety in people with anxiety disorders.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ After adjusting for various confounders, tea intake was associated with lower blood glucose levels in non-obese (P for trend < 0.001), but not in obese people (P = 0.24).
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

[69]
.With these effects, caffeine is an ergogenic, increasing a person's capability for mental or physical labor.^ Caffeine induced alerting effects in various tests and differed from triazolam in some (digit substitution, drowsiness, calmness, mental slowness) but not all variables measured.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ Increased anxiogenic effects of caffeine in panic disorders.
  • Caffeine for the Sustainment of Mental Task Performance: Formulations for Military Operations 19 January 2010 8:49 UTC www.nap.edu [Source type: Academic]

^ These data support prior reports that panic patients have increased sensitivity to caffeine; some depressed patients may also have increased sensitivity.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

.A study conducted in 1979 showed a 7% increase in distance cycled over a period of two hours in subjects that consumed caffeine compared to control subjects.^ In another study ( Lane, 1996 ) it was found that the rate of smoking was higher during such periods of the day when caffeine-containing beverages were consumed than during other parts of the day.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ Recent references are Pastore and Savitz, Case-control study of caffeinated beverages and preterm delivery.
  • Coffee and Caffeine FAQ 15 September 2009 6:10 UTC www.nootropics.com [Source type: FILTERED WITH BAYES]
  • Coffee and Caffeine's Frequently Asked Questions 19 January 2010 8:49 UTC www.faqs.org [Source type: FILTERED WITH BAYES]
  • Frequently Asked Questions about Coffee and Caffeine 19 January 2010 8:49 UTC www.indwes.edu [Source type: FILTERED WITH BAYES]

^ The effects of caffeine and smoking on cognitive performance, subjective variables, heart rate, and EEG were assessed in two sessions.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

[70] .Other studies attained much more dramatic results; one particular study of trained runners showed a 44% increase in "race-pace" endurance, as well as a 51% increase in cycling endurance, after a dosage of 9 milligrams of caffeine per kilogram of body weight.^ It seems to show much more relevant results.

^ One final note: this would probably be even better with iced espresso, because the espresso is so much more powerful and loses its taste less when it's cold.
  • Coffee and Caffeine FAQ 15 September 2009 6:10 UTC www.nootropics.com [Source type: FILTERED WITH BAYES]
  • Coffee and Caffeine's Frequently Asked Questions 19 January 2010 8:49 UTC www.faqs.org [Source type: FILTERED WITH BAYES]

^ The sensitivity analysis which means removing one study at a time confirmed the stability of our results.
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

[71] .Additional studies have reported similar effects.^ In addition, this self-report survey suggested that patients with panic disorder had an increased sensitivity to the effects of one cup of coffee.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ The effect was similar to that of acetaminophen, which is frequently combined with caffeine, and showed no relation to the effects on mood or to self-reported coffee drinking.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ Seventy-one percent of the patients reported that the behavioral effects of caffeine were similar to those experienced during panic attacks.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

.Another study found 5.5 milligrams of caffeine per kilogram of body mass resulted in subjects cycling 29% longer during high-intensity circuits.^ Caffeine can affect velocity in the middle cerebral artery during hyperventilation, hypoventilation, and thinking: A transcranial doppler study.
  • Caffeine for the Sustainment of Mental Task Performance: Formulations for Military Operations 19 January 2010 8:49 UTC www.nap.edu [Source type: Academic]

^ In another study ( Lane, 1996 ) it was found that the rate of smoking was higher during such periods of the day when caffeine-containing beverages were consumed than during other parts of the day.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ We found reduced saccadic interruptions as a result of caffeine ingestion compared with placebo (p less than .05).
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

[72]
.Caffeine citrate has proven to be of short- and long-term benefit in treating the breathing disorders of apnea of prematurity and bronchopulmonary dysplasia in premature infants.^ Normal caffeine use in humans is long-term, oral use, whereas the experiments in rodents used single parenteral administrations.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ The adaptive changes to long-term caffeine are very dramatic, being not only quantitatively different from but often opposite to the acute effects of caffeine in normal and pathological conditions.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ A fourth infant (premature) attained a high plasma caffeine concentration, but this infant's symptoms were altered by intraventricular hemorrhage.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

[68] .The only short-term risk associated with caffeine citrate treatment is a temporary reduction in weight gain during the therapy,[73] and longer term studies (18 to 21 months) have shown lasting benefits of treatment of premature infants with caffeine.^ This initial screening was followed by an 18-day treatment period for which the subjects were split into a placebo and a caffeine group, balanced for caffeine choosers and nonchoosers.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ The adaptive changes to long-term caffeine are very dramatic, being not only quantitatively different from but often opposite to the acute effects of caffeine in normal and pathological conditions.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ A fourth infant (premature) attained a high plasma caffeine concentration, but this infant's symptoms were altered by intraventricular hemorrhage.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

[74][75]
.Caffeine relaxes the internal anal sphincter muscles and thus should be avoided by those with fecal incontinence.^ Those who easily become anxious should avoid caffeine.
  • Bulk Nutrition - Caffeine Description by David Tolson 19 January 2010 8:49 UTC www.bulknutrition.com [Source type: Academic]

^ Opposite actions of caffeine and creatine on muscle relaxation time in humans .
  • Bulk Nutrition - Caffeine Description by David Tolson 19 January 2010 8:49 UTC www.bulknutrition.com [Source type: Academic]

^ Therefore, it should be emphasized that individuals suffering from epilepsy should avoid, or at least reduce consumption of coffee and other caffeine-containing beverages.
  • Coffee and Caffeine FAQ 15 September 2009 6:10 UTC www.nootropics.com [Source type: FILTERED WITH BAYES]
  • Coffee and Caffeine's Frequently Asked Questions 19 January 2010 8:49 UTC www.faqs.org [Source type: FILTERED WITH BAYES]
  • Frequently Asked Questions about Coffee and Caffeine 19 January 2010 8:49 UTC www.indwes.edu [Source type: FILTERED WITH BAYES]

[76]
.While relatively safe for humans, caffeine is considerably more toxic to some other animals such as dogs, horses, and parrots due to a much poorer ability to metabolize this compound.^ It has been suggested that the subjects most sensitive to the effects of coffee on sleep might metabolize caffeine more slowly than the others ( Levy and Zylber-Katz, 1983 ).
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ In that study, caffeine dose-dependently increased ratings of positive mood, and the higher doses of caffeine were more frequently identified with other stimulant drugs like amphetamine and cocaine.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ Although not significantly different, the flurazepam, 30 mg, group demonstrated a trend toward poorer performance and a more negative mood than all other groups.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

.Caffeine has also a pronounced effect on mollusks and various insects as well as spiders.^ The effects of caffeine and smoking on cognitive performance, subjective variables, heart rate, and EEG were assessed in two sessions.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ Caffeine induced alerting effects in various tests and differed from triazolam in some (digit substitution, drowsiness, calmness, mental slowness) but not all variables measured.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ Rationale The effects of caffeine on mood and performance are well established.
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

[77]

Tolerance and withdrawal

.Because caffeine is primarily an antagonist of the central nervous system's receptors for the neurotransmitter adenosine, the bodies of individuals that regularly consume caffeine adapt to the continuous presence of the drug by substantially increasing the number of adenosine receptors in the central nervous system.^ The role of adenosine receptors in the central action of caffeine.
  • Caffeine for the Sustainment of Mental Task Performance: Formulations for Military Operations 19 January 2010 8:49 UTC www.nap.edu [Source type: Academic]

^ Adenosine, adenosine receptors and the actions of caffeine.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ Caffeine is the most widely consumed central-nervous-system stimulant.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

.This increase in the number of the adenosine receptors makes the body much more sensitive to adenosine, with two primary consequences.^ There is indeed ample evidence that caffeine (and other adenosine receptor antagonists) can increase behaviors related to dopamine.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ Blockade of methylxanthine-sensitive adenosine receptors is the currently accepted mechanism of action of caffeine.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ It is therefore important to consider where these two adenosine receptors are located.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

[78] .First, the stimulatory effects of caffeine are substantially reduced, a phenomenon known as a tolerance adaptation.^ Caffeine increased resting electrodermal activity (EDA) and increased the SC orienting response to the first non-signal tone, but reduced the increase in tonic EDA due to task performance.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ This study provides the clearest evidence to date of complete tolerance development to a CNS effect of caffeine in humans.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ The central nervous system does not seem to develop a great tolerance to the effects of caffeine although dependence and withdrawal symptoms are reported.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

.Second, because these adaptive responses to caffeine make individuals much more sensitive to adenosine, a reduction in caffeine intake will effectively increase the normal physiological effects of adenosine, resulting in unwelcome withdrawal symptoms in tolerant users.^ In line with these effects, caffeine intake has been associated with increased risk of heart attack 1 .
  • Bulk Nutrition - Caffeine Description by David Tolson 19 January 2010 8:49 UTC www.bulknutrition.com [Source type: Academic]

^ However, increased sensitivity to caffeine in these patients has been suggested as contributing to their symptoms.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ Physiological responses to caffeine during endurance running in habitual caffeine users.
  • Caffeine for the Sustainment of Mental Task Performance: Formulations for Military Operations 19 January 2010 8:49 UTC www.nap.edu [Source type: Academic]

[78]
.Other research questions the idea that up-regulation of adenosine receptors is responsible for tolerance to the locomotor stimulant effects of caffeine, noting, among other things, that this tolerance is insurmountable by higher doses of caffeine (it should be surmountable if tolerance were due to an increase in receptors), and that the increase in adenosine receptor number is modest and does not explain the large tolerance that develops to caffeine.^ Tolerance to caffeine-induced stimulation of locomotor activity in rats.
  • Caffeine for the Sustainment of Mental Task Performance: Formulations for Military Operations 19 January 2010 8:49 UTC www.nap.edu [Source type: Academic]

^ The methylxanthine induces dose-response increases in locomotor activity in animals.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ Thus, cerebral energy metabolism does not seem to develop tolerance to the stimulant effects of caffeine.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

[79]
.Caffeine tolerance develops very quickly, especially among heavy coffee and energy drink consumers.^ CrossRef Medline ↵ Colton T , Gosselin RE , Smith RP ( 1968 ) The tolerance of coffee drinkers to caffeine.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ This study provides the clearest evidence to date of complete tolerance development to a CNS effect of caffeine in humans.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ In addition, it is well known that smokers are particularly liable to smoke when drinking coffee, whereas, on the other hand, coffee is consumed more in the morning and alcohol in the evening.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

.Complete tolerance to sleep disruption effects of caffeine develops after consuming 400 mg of caffeine 3 times a day for 7 days.^ Tolerance develops to some caffeine effects but not to others.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ Secondary analyses of data collected after a day of normal caffeine consumption were also carried out to examine some alternative explanations of their results which showed effects of caffeine after a day of normal caffeine consumption.
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

^ Okuma T, Matsuoka H, Matsue Y, Toyomura K Experimental sleep disturbances (model insomnia) were produced by the administration of methylphenidate (MPD) 10 mg and caffeine (CAF) 150 mg.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

.Complete tolerance to subjective effects of caffeine was observed to develop after consuming 300 mg 3 times per day for 18 days, and possibly even earlier.^ Tolerance develops to some caffeine effects but not to others.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ Subsequently, subjects received either caffeine (300 mg t.i.d.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ However, virtually complete tolerance to the increase of locomotor activity was observed in rats consuming approximately 40 mg/kg caffeine per day via their drinking water ( Finn and Holtzman, 1986 ), and this was accompanied by a downward displacement and flattening of the dose-response curve.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

[80] .In another experiment, complete tolerance of caffeine was observed when the subject consumed 750–1200 mg per day while incomplete tolerance to caffeine has been observed in those that consume more average doses of caffeine.^ However, virtually complete tolerance to the increase of locomotor activity was observed in rats consuming approximately 40 mg/kg caffeine per day via their drinking water ( Finn and Holtzman, 1986 ), and this was accompanied by a downward displacement and flattening of the dose-response curve.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ In another study ( Lane, 1996 ) it was found that the rate of smoking was higher during such periods of the day when caffeine-containing beverages were consumed than during other parts of the day.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ In one session, subjects received caffeine (2.5 mg/kg bodyweight), while in the other they received placebo.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

[81]
.Because adenosine, in part, serves to regulate blood pressure by causing vasodilation, the increased effects of adenosine due to caffeine withdrawal cause the blood vessels of the head to dilate, leading to an excess of blood in the head and causing a headache and nausea.^ Caffeine, blood pressure, and serum lipids.
  • Caffeine for the Sustainment of Mental Task Performance: Formulations for Military Operations 19 January 2010 8:49 UTC www.nap.edu [Source type: Academic]

^ In response to this oversensitiveness, blood pressure drops dramatically, causing an excess of blood in the head (though not necessarily on the brain), leading to a headache.
  • Coffee and Caffeine's Frequently Asked Questions 19 January 2010 8:49 UTC www.faqs.org [Source type: FILTERED WITH BAYES]
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^ Caffeine raises blood pressure at work.
  • Caffeine for the Sustainment of Mental Task Performance: Formulations for Military Operations 19 January 2010 8:49 UTC www.nap.edu [Source type: Academic]

.Reduced catecholamine activity may cause feelings of fatigue and drowsiness.^ Caffeine has long been suspect of causing mal-formations in fetus, and that it may reduce fertility rates.
  • Frequently Asked Questions about Coffee and Caffeine 19 January 2010 8:49 UTC www.indwes.edu [Source type: FILTERED WITH BAYES]

^ Moreover, this effect may be related to antagonism of a tonic inhibitory activity of adenosine A 1 receptors that reduce cholinergic transmission (cf.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ Carbohydrate and fluid intake before, during, and after a workout may help to reduce fatigue and enhance performance.
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

.A reduction in serotonin levels when caffeine use is stopped can cause anxiety, irritability, inability to concentrate, and diminished motivation to initiate or to complete daily tasks; in extreme cases it may cause mild depression.^ Symptoms of depression and anxiety were related to caffeine use.
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

^ High correlation has been obtained between the kynurenine concentration and initial values of personal and reactive anxiety.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ CrossRef Medline ↵ Hicks RA , Hicks GJ , Reyes JR , Cheers Y ( 1983 ) Daily caffeine use and the sleep of college students.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

Together, these effects have come to be known as a "crash".[82]
.Withdrawal symptoms — possibly including headache, irritability, an inability to concentrate, drowsiness, insomnia and pain in the stomach, upper body, and joints[83] — may appear within 12 to 24 hours after discontinuation of caffeine intake, peak at roughly 48 hours, and usually last from one to five days, representing the time required for the number of adenosine receptors in the brain to revert to "normal" levels, uninfluenced by caffeine consumption.^ Withdrawal of caffeine, even from moderate intake levels, can produce symptoms such as headache, fatigue and anxiety.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ When caffeine intake is reduced, the body becomes oversensitive to adenosine.
  • Coffee and Caffeine's Frequently Asked Questions 19 January 2010 8:49 UTC www.faqs.org [Source type: FILTERED WITH BAYES]

^ Adenosine, adenosine receptors and the actions of caffeine.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

.Analgesics, such as aspirin, can relieve the pain symptoms, as can a small dose of caffeine.^ This may be the first evidence for direct neurochemical changes induced by such low, clearly stimulant doses of caffeine.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ However, also a dose of caffeine taken in the morning can have such effects the following night ( Landolt et al., 1995b ).
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ Withdrawal of caffeine, even from moderate intake levels, can produce symptoms such as headache, fatigue and anxiety.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

[84] .Most effective is a combination of both an analgesic and a small amount of caffeine.^ Caffeine is used therapeutically in combination with ergotamine for migraine headaches and in combination with nonsteroidal anti-inflammatory drugs in analgesic formulations.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ Caffeine, in addition to being a food constituent, is also a common analgesic adjuvant that is used in combination with aspirin in certain over-the-counter preparations.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ We conclude that caffeine ingestion is likely to produce small but significant gains in 5-km running performance for both well-trained and recreational runners.
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

.This is not the only case in which caffeine increases the effectiveness of a drug.^ Mikkelsen EJ Two cases are described in which markedly increased consumption of caffeine led to an exacerbation of a schizophrenic process.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ In that study, caffeine dose-dependently increased ratings of positive mood, and the higher doses of caffeine were more frequently identified with other stimulant drugs like amphetamine and cocaine.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ This was taken as evidence that adenosine receptor antagonism may not be the only mechanism by which caffeine causes an increased rotation behavior ( Garrett and Holtzman, 1994b ).
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

.Caffeine makes pain relievers 40% more effective in relieving headaches and helps the body absorb headache medications more quickly, bringing faster relief.^ More subjects reported unauthorized use of medications during the placebo period (13 percent) than during the caffeine period (2 percent, P = 0.017).
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ Mothers who consumed more caffeine also smoked more often, were younger, were less educated, reported less sleep effectiveness and more obstetric complications.
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

^ In their pioneering study on caffeine withdrawal, Dreisbach and Pfeiffer (1943) observed that caffeine was highly efficient in relieving withdrawal headache.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

[85] .For this reason, many over-the-counter headache drugs include caffeine in their formula.^ However few behavioral studies have examined this substance's acute effects when administered in a range of doses that include the low doses typically found in foods and over-the-counter drugs.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ Caffeine is used therapeutically in combination with ergotamine for migraine headaches and in combination with nonsteroidal anti-inflammatory drugs in analgesic formulations.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ Conclusion(s): The expectation of receiving caffeine under alcohol is sufficient to counter-act the impairing effects of the drug.
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

.It is also used with ergotamine in the treatment of migraine and cluster headaches as well as to overcome the drowsiness caused by antihistamines.^ Caffeine is used therapeutically in combination with ergotamine for migraine headaches and in combination with nonsteroidal anti-inflammatory drugs in analgesic formulations.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

Overuse

.In large amounts, and especially over extended periods of time, caffeine can lead to a condition known as caffeinism.[86][87] Caffeinism usually combines caffeine dependency with a wide range of unpleasant physical and mental conditions including nervousness, irritability, anxiety, tremulousness, muscle twitching (hyperreflexia), insomnia, headaches, respiratory alkalosis, and heart palpitations.^ The lower dose of caffeine produced more favorable subjective effects than the higher dose (elation, peacefulness, pleasantness), whereas unpleasant effects (tension, nervousness, anxiety, excitement, irritability, nausea, palpitations, restlessness) following the 500-mg dose exceeded those of the 250-mg dose.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ The present study examined cardiovascular responses to the combination of caffeine (250mg) and mental arithmetic, cold pressor, and static exercise stressors in 48 healthy males.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ Both caffeine doses reduced electroencephalographic amplitude over the 4 Hz to 30 Hz spectrum, as well as in the alpha (8-11 Hz) and beta (12-30 Hz) ranges; however, effects were not dose-dependent.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

[88][89] .Furthermore, because caffeine increases the production of stomach acid, high usage over time can lead to peptic ulcers, erosive esophagitis, and gastroesophageal reflux disease.^ These results suggest that even a single, albeit high, dose of caffeine can induce changes in gene expression that could lead to adaptive changes in the brain.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ It appears that anxiety disorder patients have increased caffeine sensitivity which leads to decreased consumption.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ These results suggest that previous reports of subjective caffeine effects are also suspect because of their failure to control for the increased probability of Type I error.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

[90]
.There are four caffeine-induced psychiatric disorders recognized by the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition: caffeine intoxication, caffeine-induced anxiety disorder, caffeine-induced sleep disorder, and caffeine-related disorder not otherwise specified (NOS).^ Furthermore, there was no relationship to the intake of caffeine in patients with anxiety.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ American Psychiatric Association ( 1994 ) Diagnostic and Statistical Manual of Mental Disorders ( American Psychiatric Association , Washington, DC. ) Revised 4th ed.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ American Psychiatric Association ( 1987 ) Diagnostic and Statistical Manual of Mental Disorders ( American Psychiatric Association , Washington, DC. ) Revised 3rd ed.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

Caffeine intoxication

Torso of a young man with overlayed text of main side-effects of caffeine overdose.
Main symptoms of caffeine intoxication.[68]
.An acute overdose of caffeine, usually in excess of about 300 milligrams, dependent on body weight and level of caffeine tolerance, can result in a state of central nervous system over-stimulation called caffeine intoxication (DSM-IV 305.90),[91] or colloquially the "caffeine jitters". The symptoms of caffeine intoxication are not unlike overdoses of other stimulants.^ The central nervous system does not seem to develop a great tolerance to the effects of caffeine although dependence and withdrawal symptoms are reported.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ Caffeine is the most widely consumed central-nervous-system stimulant.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ Caffeine commonly causes symptoms of an acute overdose and withdrawal symptoms.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

.It may include restlessness, nervousness, excitement, insomnia, flushing of the face, increased urination, gastrointestinal disturbance, muscle twitching, a rambling flow of thought and speech, irritability, irregular or rapid heart beat, and psychomotor agitation.^ The short term consumption of caffeine may result in increased urination, gastrointestinal distress, tremors, decreased sleep, and anxiety symptoms in certain individuals.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ Caffeine produced significantly greater increases in subject-rated anxiety, nervousness, fear, nausea, palpitations, restlessness, and tremors in the patients compared with healthy subjects.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ Caffeine may produce symptoms of anxiety-nervousness without increasing central norepinephrine turnover.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

[89] In cases of much larger overdoses, mania, depression, lapses in judgment, disorientation, disinhibition, delusions, hallucinations, and psychosis may occur, and rhabdomyolysis (breakdown of skeletal muscle tissue) can be provoked.[92][93]
In cases of extreme overdose, death can result. .The median lethal dose (LD50) given orally, is 192 milligrams per kilogram in rats.^ Malformations have been demonstrated in mice at 50-75 mg/kg of caffeine, whereas the lowest dose usually needed to induce malformations is 80 mg/kg in rats.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ Indeed, the effect seen at the lowest dose was almost 75% of that maximally observed, suggesting that the threshold effect may be on the order of a few milligrams per kilogram.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ Caffeine given as an acute dose of 10 mg/kg increases the rates of cerebral energy metabolism in the rat.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

[2] .The LD50 of caffeine in humans is dependent on weight and individual sensitivity and estimated to be about 150 to 200 milligrams per kilogram of body mass, roughly 80 to 100 cups of coffee for an average adult taken within a limited time frame that is dependent on half-life.^ Abstract / FREE Full Text ↵ Stern KN , Chait LD , Johanson CE ( 1989 ) Reinforcing and subjective effects of caffeine in normal human volunteers.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ In addition, this self-report survey suggested that patients with panic disorder had an increased sensitivity to the effects of one cup of coffee.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ Malformations have been demonstrated in mice at 50-75 mg/kg of caffeine, whereas the lowest dose usually needed to induce malformations is 80 mg/kg in rats.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

.Though achieving lethal dose with caffeine would be exceptionally difficult with regular coffee, there have been reported deaths from overdosing on caffeine pills, with serious symptoms of overdose requiring hospitalization occurring from as little as 2 grams of caffeine.^ There are also several reports on caffeine abstinence and postoperative headaches ( Fennelly et al., 1991 ; Weber et al., 1993 ; Nikolajsen et al., 1994 ).
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ However, as discussed below (Section IX) such constant and regular intake has not been possible to achieve with caffeine in animals and hence there are no reliable animal data relating to this point.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ A review of 86 studies of nicotine withdrawal, caffeine withdrawal, and caffeine toxicity suggests that the symptoms are similar enough to be confused, and that reported nicotine withdrawal symptoms may be a mixture of nicotine withdrawal and caffeine toxicity.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

.An exception to this would be taking a drug such as fluvoxamine, which blocks the liver enzyme responsible for the metabolism of caffeine, thus increasing the central effects and blood concentrations of caffeine dramatically at 5-fold.^ Caffeine increases maximal anaerobic power and blood lactate concentration.
  • Caffeine for the Sustainment of Mental Task Performance: Formulations for Military Operations 19 January 2010 8:49 UTC www.nap.edu [Source type: Academic]

^ Caffeine restriction: Effect on blood pressure.
  • Caffeine for the Sustainment of Mental Task Performance: Formulations for Military Operations 19 January 2010 8:49 UTC www.nap.edu [Source type: Academic]

^ Moderation in all caffeine containing products is the basic rule of thumb for the positive attributes without the undesireable effects of taking too much.
  • Bodybuilding.com - Caffeine Information and Product Listing! Caffeine FAQ! 15 September 2009 6:10 UTC www.bodybuilding.com [Source type: FILTERED WITH BAYES]

.It is not contraindicated, but highly advisable to minimize the intake of caffeinated beverages, as drinking one cup of coffee will have the same effect as drinking five under normal conditions.^ Astorino TA; Rohmann RL; Firth K. Effect of caffeine ingestion on one-repetition maximum muscular strength.
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

^ One month later the effect of caffeine alone was tested.
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

^ Indeed, not less than 14% of all erstwhile consumers in Vermont had stopped the intake of all caffeine-containing beverages largely for this reason ( Hughes and Oliveto, 1997 ).
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

[94][95][96][97] .Death typically occurs due to ventricular fibrillation brought about by effects of caffeine on the cardiovascular system.^ Cardiovascular effects of caffeine.
  • Caffeine for the Sustainment of Mental Task Performance: Formulations for Military Operations 19 January 2010 8:49 UTC www.nap.edu [Source type: Academic]

^ The central nervous system does not seem to develop a great tolerance to the effects of caffeine although dependence and withdrawal symptoms are reported.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ Given that many caffeine-containing drinks are typically consumed in social settings, surprisingly little is known about the possible effects of caffeine on social behavior (see Bättig and Welzl, 1993 ).
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

.Treatment of severe caffeine intoxication is generally supportive, providing treatment of the immediate symptoms, but if the patient has very high serum levels of caffeine then peritoneal dialysis, hemodialysis, or hemofiltration may be required.^ Serum caffeine levels confirmed compliance.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ Thus, the levels of caffeine may be at least as high.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ Patients with high anxiety scores due to depression do not appear to be supersensitive to caffeine ( Boulenger et al., 1984 ).
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

Detection in biological fluids

.Caffeine may be quantitated in blood, plasma or serum to monitor therapy in neonates, confirm a diagnosis of poisoning in hospitalized patients or assist in a medicolegal death investigation.^ An alternative approach to blood pressure monitoring would be to ask the patient about recent caffeine consumption and interpret the blood pressure reading based on this information.
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

^ These data support prior reports that panic patients have increased sensitivity to caffeine; some depressed patients may also have increased sensitivity.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ Patients with anxiety disorders may benefit by avoiding caffeine-containing foods and beverages.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

.Urine caffeine concentrations are frequently measured in competitive sports programs, for which a level in excess of 15 mg/L is usually considered to represent abuse.^ Caffeine pharmacokinetics were assessed by measurement of saliva caffeine concentrations.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ Peak plasma caffeine concentration is reached between 15 and 120 min after oral ingestion in humans and equals 8 to 10 mg/l for doses of 5 to 8 mg/kg ( Arnaud and Welsch, 1982 ; Bonati et al., 1982 ).
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ Sublethal effects measured for caffeine exposure included impaired C. dubia reproduction (IC50 = 44 mg/L) and inhibited P. promelas growth (IC50 = 71 mg/L).
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

[98]

Anxiety and sleep disorders

.Two infrequently diagnosed caffeine-induced disorders that are recognized by the American Psychological Association (APA) are caffeine-induced sleep disorder and caffeine-induced anxiety disorder, which can result from long-term excessive caffeine intake.^ Similar associations were observed for caffeine intake.
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

^ Copyright 2008, American Psychological Association .
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

^ Caffeine increases anxiety in people with anxiety disorders.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

.In the case of caffeine-induced sleep disorder, an individual regularly ingests high doses of caffeine sufficient to induce a significant disturbance in his or her sleep, sufficiently severe to warrant clinical attention.^ Okuma T, Matsuoka H, Matsue Y, Toyomura K Experimental sleep disturbances (model insomnia) were produced by the administration of methylphenidate (MPD) 10 mg and caffeine (CAF) 150 mg.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ This may be the first evidence for direct neurochemical changes induced by such low, clearly stimulant doses of caffeine.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ Sleep disorders constitute a major predictor for depression ( Chang et al., 1997 ), and caffeine is known to affect sleep.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

[91]
.In some individuals, the large amounts of caffeine can induce anxiety severe enough to necessitate clinical attention.^ The physiological effects are partially similar to the effects seen in clinical anxiety states, and they are also consistent with the physiological concomitants of good sustained attention.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ Anxiety disorder patients do not consume toxic amounts of caffeine.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ The short term consumption of caffeine may result in increased urination, gastrointestinal distress, tremors, decreased sleep, and anxiety symptoms in certain individuals.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

.This caffeine-induced anxiety disorder can take many forms, from generalized anxiety to panic attacks, obsessive-compulsive symptoms, or even phobic symptoms.^ Caffeine increases anxiety in people with anxiety disorders.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ Caffeine is believed to induce anxiety in normal people and anxiety disorder patients and panic attacks in panic disorder patients.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ Anxiety disorder patients do not consume toxic amounts of caffeine.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

[91] .Because this condition can mimic organic mental disorders, such as panic disorder, generalized anxiety disorder, bipolar disorder, or even schizophrenia, a number of medical professionals believe caffeine-intoxicated people are routinely misdiagnosed and unnecessarily medicated when the treatment for caffeine-induced psychosis would simply be to stop further caffeine intake.^ Caffeine toxicity remains a rarely reported condition, which may mimic anxiety disorders.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ Caffeine increases anxiety in people with anxiety disorders.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ Caffeine is believed to induce anxiety in normal people and anxiety disorder patients and panic attacks in panic disorder patients.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

[99] .A study in the British Journal of Addiction concluded that caffeinism, although infrequently diagnosed, may afflict as many as one person in ten of the population.^ Although no impact is observed on dementia incidence, further studies are required to ascertain whether caffeine may nonetheless be of potential use in prolonging the period of mild cognitive impairment in women prior to a diagnosis of dementia.
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

^ We analyzed the association of personality traits with both caffeine intake and smoking, controlling the possible confounding effects of sex, age and each substance with the other one.
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

^ It is suggested that caffeine use is one of the important factors, in researching psychological health among the general population.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

[87] .Co administration of theanine was shown to greatly reduce this caffeine-induced anxiety.^ When caffeine was added together with NCS to the culture of HeLa-S3 cells, NCS-induced inhibition of DNA synthesis and of mitosis was markedly reduced in the presence of caffeine.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ Although depressed patients did not differ from control subjects in caffeine intake or most symptoms, more depressed patients reported that caffeine induced anxiety.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ Acute exercise reduces caffeine-induced anxiogenesis.
  • Caffeine for the Sustainment of Mental Task Performance: Formulations for Military Operations 19 January 2010 8:49 UTC www.nap.edu [Source type: Academic]

[100]

Effects on memory and learning

Photo of a capped chemical bottle on a table.
Anhydrous caffeine
.An array of studies found that caffeine could have nootropic effects, inducing certain changes in memory and learning.^ Effect of caffeine and nicotine on avoidance learning in mice: Lack of interaction.
  • Caffeine for the Sustainment of Mental Task Performance: Formulations for Military Operations 19 January 2010 8:49 UTC www.nap.edu [Source type: Academic]

^ The effects of caffeine on learning, memory, performance and coordination are rather related to the methylxanthine action on arousal, vigilance and fatigue.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ In some studies, the effects of caffeine are even weaker in this regard than those of nicotine, which is notoriously unreliable as a reinforcing drug.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

.Researchers have found that long-term consumption of low dose caffeine slowed hippocampus-dependent learning and impaired long-term memory in mice.^ Low-dose caffeine physical dependence in humans.
  • Caffeine for the Sustainment of Mental Task Performance: Formulations for Military Operations 19 January 2010 8:49 UTC www.nap.edu [Source type: Academic]

^ This may be the first evidence for direct neurochemical changes induced by such low, clearly stimulant doses of caffeine.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ Maternal consumption of caffeine affects brain composition, especially in case of a low-protein diet and also seems to interfere with zinc fixation in brain.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

.Caffeine consumption for 4 weeks also significantly reduced hippocampal neurogenesis compared to controls during the experiment.^ We found reduced saccadic interruptions as a result of caffeine ingestion compared with placebo (p less than .05).
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ For example, it must be kept in mind that in most experiments on rodents, one single high dose of caffeine is administered, whereas human consumption of coffee is divided up during the day.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ Caffeine consumption did not reduce dementia risk over 4 years.
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

.The conclusion was that long-term consumption of caffeine could inhibit hippocampus-dependent learning and memory partially through inhibition of hippocampal neurogenesis.^ The effects of caffeine on learning, memory, performance and coordination are rather related to the methylxanthine action on arousal, vigilance and fatigue.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ In a double-blind crossover study of 26 long-stay schizophrenic patients, no correlation was found between caffeine consumption and levels of anxiety and depression.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ Normal caffeine use in humans is long-term, oral use, whereas the experiments in rodents used single parenteral administrations.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

[101].
.In another study, caffeine was added to rat neurons in vitro.^ Another study from the same laboratory ( Silverman et al., 1994 ) revealed that situational conditions might have a substantial effect on caffeine reinforcement.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ Abstract / FREE Full Text ↵ Calabresi P , Lacey MG , North RA ( 1989 ) Nicotinic excitation of rat ventral tegmental neurones in vitro studied by intracellular recording.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ Essentially similar results were obtained in a rat study where rats self-administering cocaine were treated with caffeine either as an i.p.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

.The dendritic spines (a part of the brain cell used in forming connections between neurons) taken from the hippocampus (a part of the brain associated with memory) grew by 33% and new spines formed.^ This association is highly variable between preparations and methods used.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ There is a weak association between caffeine and alcohol consumption, which is stronger if the drugs are used heavily ( Istvan and Matarazzo, 1984 ).
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ In these regions of the brain there is a marked discrepancy between the distribution of the receptor and the corresponding mRNA. This suggests that many of the adenosine A 1 receptors in the area of the DA cell bodies are located not on the dopaminergic neurons, but on the terminals of the input neurons.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

After an hour or two, however, these cells returned to their original shape.[102]
.Another study showed that human subjects — after receiving 100 milligrams of caffeine — had increased activity in brain regions located in the frontal lobe, where a part of the working memory network is located, and the anterior cingulate cortex, a part of the brain that controls attention.^ The effects of caffeine on mood have been studied in human subjects.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ At week 2, the other 6 subjects received caffeine.
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

^ These results suggest that caffeine modulates neuronal activity as evidenced by fMRI signal changes in a network of brain areas associated with executive and attentional functions during working memory processes.
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

.The caffeinated subjects also performed better on the memory tasks.^ The effects of caffeine on learning, memory, performance and coordination are rather related to the methylxanthine action on arousal, vigilance and fatigue.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ Caffeine increased resting electrodermal activity (EDA) and increased the SC orienting response to the first non-signal tone, but reduced the increase in tonic EDA due to task performance.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ The effects of caffeine and smoking on cognitive performance, subjective variables, heart rate, and EEG were assessed in two sessions.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

[103]
.However, a different study showed that caffeine could impair short-term memory and increase the likelihood of the tip of the tongue phenomenon.^ [K]o, however, caffeine could increase the upstroke of slow response and the force.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ In that study, caffeine dose-dependently increased ratings of positive mood, and the higher doses of caffeine were more frequently identified with other stimulant drugs like amphetamine and cocaine.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ The adaptive changes to long-term caffeine are very dramatic, being not only quantitatively different from but often opposite to the acute effects of caffeine in normal and pathological conditions.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

.The study allowed the researchers to suggest that caffeine could aid short-term memory when the information to be recalled is related to the current train of thought, but also to hypothesize that caffeine hinders short-term memory when the train of thought is unrelated.^ The effects of caffeine on learning, memory, performance and coordination are rather related to the methylxanthine action on arousal, vigilance and fatigue.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ The purpose of this study was to investigate if caffeine ingestion improves 5-km time-trial performance in well-trained and recreational runners.
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

^ These results suggest that even a single, albeit high, dose of caffeine can induce changes in gene expression that could lead to adaptive changes in the brain.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

[104] .In essence, caffeine consumption increases mental performance related to focused thought while it may decrease broad-range thinking abilities.^ The effects of caffeine on learning, memory, performance and coordination are rather related to the methylxanthine action on arousal, vigilance and fatigue.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ Caffeine increased resting electrodermal activity (EDA) and increased the SC orienting response to the first non-signal tone, but reduced the increase in tonic EDA due to task performance.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ There is indeed ample evidence that caffeine (and other adenosine receptor antagonists) can increase behaviors related to dopamine.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

Effects on the heart

.Caffeine binds to receptors on the surface of heart muscle cells, which leads to an increase in the level of cAMP inside the cells (by blocking the enzyme that degrades cAMP), mimicking the effects of epinephrine (which binds to receptors on the cell that activate cAMP production).^ There is indeed ample evidence that caffeine (and other adenosine receptor antagonists) can increase behaviors related to dopamine.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ Background: Clopidogrel inhibits the platelet P2Y12 receptor, leading to increased intracellular cyclic AMP (CAMP) levels.
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^ Holtzman (1996) also found that the adenosine analog CGS 21680 blocked the effect of CGS 15943, indicating a role of A 2A receptors.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

cAMP acts as a ."second messenger," and activates a large number of protein kinase A (PKA; cAMP-dependent protein kinase).^ A second factor that limits its usefulness as a radioligand is that it is an agonist and that its affinity consequently depends on the association of the receptor with G-proteins.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ Indeed, there is evidence that cAMP-dependent protein kinase is very important in the acquisition of cocaine self-administration and also in relapse into cocaine-seeking behavior ( Self et al., 1998 ).
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

.This has the overall effect of increasing the rate of glycolysis and increases the amount of ATP available for muscle contraction and relaxation.^ Results: Nicotine increased heart rate and subjective ratings indicative of aversive effects, and decreased reaction times.
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

^ Abstract / FREE Full Text ↵ Myers DE , Shaikh Z , Zullo TG ( 1997 ) Hypoalgesic effect of caffeine in experimental ischemic muscle contraction pain.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ Pairing with quinine increased the rated bitterness of the tea odour, and reduced the rated sweetness of the tea flavour, post-training, independent of effects of caffeine.
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

.According to one study, caffeine in the form of coffee, significantly reduces the risk of heart disease in epidemiological studies.^ Caffeine consumption did not reduce dementia risk over 4 years.
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

^ A lower risk of coronary heart disease among moderate coffee drinkers might be due to antioxidants found coffee.
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

^ Results: Coffee and caffeine consumption at all 3 time points were unrelated to total miscarriage risk and the risk of loss after the interview.
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

.However, the protective effect was found only in participants who were not severely hypertensive (i.e., patients that are not suffering from a very high blood pressure).^ Effect of coffee on ambulatory blood pressure in patients with hypertension.
  • Caffeine for the Sustainment of Mental Task Performance: Formulations for Military Operations 19 January 2010 8:49 UTC www.nap.edu [Source type: Academic]

^ Caffeine restriction: Effect on blood pressure.
  • Caffeine for the Sustainment of Mental Task Performance: Formulations for Military Operations 19 January 2010 8:49 UTC www.nap.edu [Source type: Academic]

^ The effects of caffeine on ambulatory blood pressure, heart rate, and mood in coffee drinkers.
  • Caffeine for the Sustainment of Mental Task Performance: Formulations for Military Operations 19 January 2010 8:49 UTC www.nap.edu [Source type: Academic]

.Furthermore, no significant protective effect was found in participants aged less than 65 years or in cerebrovascular disease mortality for those aged equal or more than 65 years.^ We found reduced saccadic interruptions as a result of caffeine ingestion compared with placebo (p less than .05).
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ A significant interaction between age and condition (IRR = 2.27 95% Cl, 1.28-4.16 P < 0.01) showed that napping led to fewer inappropriate line crossings in younger participants than in middle-aged participants.
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

^ MEASUREMENTS--Gestational age was determined from ultrasound and maternal dates; preterm birth was defined as less than 37 completed weeks.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

[105]

Effects on children

.It is a common myth that excessive intake of caffeine results in stunted growth within children, particularly younger children and teenagers.^ Because caffeine is so widely available and frequently consumed by children, these results are important and need replication.
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^ Since caffeine plasma levels were indistinguishable between suppressors and nonsuppressors we reject that excessive caffeine intake accounts for DST nonsuppression among individuals with schizophrenia.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ To determine whether caffeine intake influenced DST results in depression, we retrospectively studied the relationship between regular daily caffeine consumption and pretreatment DST status in major depressives.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

[106] - recently, scientific studies have disproved the notion. .Children are found to experience the same effects from caffeine as adults.^ The reinforcing and subjective effects of caffeine (100 and 300 mg, PO) were determined in a group of 18 normal, healthy adults.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ This double-blind cross-over pilot study evaluated the effect of ibuprofen and caffeine compared with ibuprofen and placebo in 12 children with headaches.
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

^ Another study from the same laboratory ( Silverman et al., 1994 ) revealed that situational conditions might have a substantial effect on caffeine reinforcement.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

.However, subsidiary beverages that contain caffeine, such as energy drinks, most of which contain high amounts of caffeine, have been banned in many schools throughout the world, due to other adverse effects having been observed in prolonged consumption of caffeine.^ Effects of caffeine consumption on delayed conception.
  • Caffeine for the Sustainment of Mental Task Performance: Formulations for Military Operations 19 January 2010 8:49 UTC www.nap.edu [Source type: Academic]

^ Objective: To describe benefits and adverse effects associated with the consumption of energy drinks.
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

^ Caffeine is consumed in many beverages and foods throughout the world.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

[107] .Furthermore, in one study, caffeinated Cola has been linked to hyperactivity in children.^ This double-blind cross-over pilot study evaluated the effect of ibuprofen and caffeine compared with ibuprofen and placebo in 12 children with headaches.
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

^ In one study it was shown that subjects involved in a discrimination study were able to make an accurate choice of caffeine or placebo ( Silverman et al., 1994 ).
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ There is some evidence for a causal link between caffeine and ethanol use from animal studies, and this relates to effects of ethanol on adenosine.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

[108]

Caffeine intake during pregnancy

.Despite its widespread use and the conventional view that it is a safe substance, a 2008 study suggested that pregnant women who consume 200 milligrams or more of caffeine per day have about twice the miscarriage risk as women who consume none.^ In another study ( Lane, 1996 ) it was found that the rate of smoking was higher during such periods of the day when caffeine-containing beverages were consumed than during other parts of the day.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ Three capsules were given per day, the caffeine capsules containing increasing amounts of caffeine with 100 mg at the start and 300 mg at the end of the treatment phase.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ Although no impact is observed on dementia incidence, further studies are required to ascertain whether caffeine may nonetheless be of potential use in prolonging the period of mild cognitive impairment in women prior to a diagnosis of dementia.
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

.However, another 2008 study found no correlation between miscarriage and caffeine consumption.^ However, there was no relationship between caffeine consumption and depressive symptoms.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ In a double-blind crossover study of 26 long-stay schizophrenic patients, no correlation was found between caffeine consumption and levels of anxiety and depression.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ In another study ( Lane, 1996 ) it was found that the rate of smoking was higher during such periods of the day when caffeine-containing beverages were consumed than during other parts of the day.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

[109] .The UK Food Standards Agency has recommended that pregnant women should limit their caffeine intake to less than 200 mg of caffeine a day—the equivalent of two cups of instant coffee or a half to two cups of fresh coffee.^ Therefore, pregnant mothers should be advised to limit their coffee and caffeine intake to 300 mg caffeine/day (i.e.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ It is thus recommended that all patients should be questioned on their caffeine intake.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ Indeed, not less than 14% of all erstwhile consumers in Vermont had stopped the intake of all caffeine-containing beverages largely for this reason ( Hughes and Oliveto, 1997 ).
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

[110][111] .The FSA noted that the design of the studies made it impossible to be certain that the differences were due to caffeine per se, instead of other lifestyle differences possibly associated with high levels of caffeine consumption, but judged the advice to be prudent.^ Differences in fertility associated with caffeinated beverage consumption.
  • Caffeine for the Sustainment of Mental Task Performance: Formulations for Military Operations 19 January 2010 8:49 UTC www.nap.edu [Source type: Academic]

^ Patients with high anxiety scores due to depression do not appear to be supersensitive to caffeine ( Boulenger et al., 1984 ).
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ Effects of black and green tea consumption on blood glucose levels in non-obese elderly men and women from Mediterranean Islands (MEDIS epidemiological study).
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

Dr De-Kun Li of Kaiser Permanente Division of Research, writing in the American Journal of Obstetrics and Gynecology, concluded that an intake of 200 milligrams or more per day, representing two or more cups, "significantly increases the risk of miscarriage".[112] However, Dr. David A. Savitz, a professor in community and preventive medicine at New York's Mount Sinai School of Medicine and lead author of the other new study on the subject published in the January issue of Epidemiology, found no link between miscarriage and caffeine consumption.[109]

Genetics and caffeine metabolism

A 2006 study by Dr. Ahmed El-Sohemy at the University of Toronto discovered a link between a gene affecting caffeine metabolism and the effects of coffee on health.[113] .Some people metabolize caffeine more slowly than the general population due to variations in a specific cytochrome P450 gene[114], and there is evidence people with this gene may be at a higher risk of myocardial infarction when consuming large amounts of coffee.^ Metabolism of caffeine and other components of coffee.
  • Caffeine for the Sustainment of Mental Task Performance: Formulations for Military Operations 19 January 2010 8:49 UTC www.nap.edu [Source type: Academic]

^ There were generally more complaints in the afternoons than in the mornings.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ Indeed, not less than 14% of all erstwhile consumers in Vermont had stopped the intake of all caffeine-containing beverages largely for this reason ( Hughes and Oliveto, 1997 ).
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

.For rapid metabolizers, however, coffee seemed to have a preventative effect.^ It has been suggested that the subjects most sensitive to the effects of coffee on sleep might metabolize caffeine more slowly than the others ( Levy and Zylber-Katz, 1983 ).
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ Thus, cerebral energy metabolism does not seem to develop tolerance to the stimulant effects of caffeine.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

.Slow and fast metabolizers are comparably common in the general population, and this has been blamed for the wide variation in studies of the health effects of caffeine.^ The studies concerning caffeine reinforcement in animals have generally examined the effect of i.v.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ Also in studies with oral intake, the reinforcing effect of caffeine varies with the dose.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ In some studies, the effects of caffeine are even weaker in this regard than those of nicotine, which is notoriously unreliable as a reinforcing drug.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

Intraocular Pressure and caffeine

.Recent data has suggested that caffeine consumption can raise intraocular pressure.^ Caffeine raises blood pressure at work.
  • Caffeine for the Sustainment of Mental Task Performance: Formulations for Military Operations 19 January 2010 8:49 UTC www.nap.edu [Source type: Academic]

^ Secondary analyses of data collected after a day of normal caffeine consumption were also carried out to examine some alternative explanations of their results which showed effects of caffeine after a day of normal caffeine consumption.
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^ An alternative approach to blood pressure monitoring would be to ask the patient about recent caffeine consumption and interpret the blood pressure reading based on this information.
  • CORK Bibliography: Caffeine 15 September 2009 6:10 UTC www.projectcork.org [Source type: Academic]

[115] This may be a significant consideration for those with open angle glaucoma.[116]

Decaffeination

.Extraction of caffeine from coffee, to produce decaffeinated coffee and caffeine, is an important industrial process and can be performed using a number of different solvents.^ The majority of caffeine is produced in decaffeinating coffee.
  • Bodybuilding.com - Caffeine Information and Product Listing! Caffeine FAQ! 15 September 2009 6:10 UTC www.bodybuilding.com [Source type: FILTERED WITH BAYES]

^ Associations between maternal decaffeinated and caffeinated coffee consumption and fetal growth and gestational duration.
  • Caffeine for the Sustainment of Mental Task Performance: Formulations for Military Operations 19 January 2010 8:49 UTC www.nap.edu [Source type: Academic]

^ The responses of the patient groups regarding caffeine and carbohydrate use did not differ from each other, but all differed significantly from the responses of normal volunteers.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

Benzene, chloroform, trichloroethylene and dichloromethane have all been used over the years but for reasons of safety, environmental impact, cost and flavor, they have been superseded by the following main methods:

Water extraction

Coffee beans are soaked in water. .The water, which contains many other compounds in addition to caffeine and contributes to the flavor of coffee, is then passed through activated charcoal, which removes the caffeine.^ Metabolism of caffeine and other components of coffee.
  • Caffeine for the Sustainment of Mental Task Performance: Formulations for Military Operations 19 January 2010 8:49 UTC www.nap.edu [Source type: Academic]

^ Caffeine is an alkaloid; of which there are numerous compounds such as the methylxanthines, with three distinguished compounds: caffeine, theophylline, and theobromine, found in guarana, kola nuts, coffee, tea, cocoa beans, mate and other plants.
  • Bodybuilding.com - Caffeine Information and Product Listing! Caffeine FAQ! 15 September 2009 6:10 UTC www.bodybuilding.com [Source type: FILTERED WITH BAYES]

^ In addition, it is well known that smokers are particularly liable to smoke when drinking coffee, whereas, on the other hand, coffee is consumed more in the morning and alcohol in the evening.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

The water can then be put back with the beans and evaporated dry, leaving decaffeinated coffee with its original flavor.[117] .Coffee manufacturers recover the caffeine and resell it for use in soft drinks and over-the-counter caffeine tablets.^ Nobody really needs caffeine, but I once read an article that said if all of America were to stop drinking coffee or caffeine-containing soft drinks/beverages, productivity would fall by 70%.
  • Bodybuilding.com - Caffeine Information and Product Listing! Caffeine FAQ! 15 September 2009 6:10 UTC www.bodybuilding.com [Source type: FILTERED WITH BAYES]

^ Rationale: Although both contain behaviourally significant concentrations of caffeine, tea is commonly perceived to be a less stimulating drink than coffee.
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^ CrossRef Medline ↵ Griffiths RR , Bigelow GE , Liebson IA ( 1986a ) Human coffee drinking: Reinforcing and physical dependence producing effects of caffeine.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

Supercritical carbon dioxide extraction

.Supercritical carbon dioxide is an excellent nonpolar solvent for caffeine, and is safer than the organic solvents that are otherwise used.^ More subjects reported unauthorized use of medications during the placebo period (13 percent) than during the caffeine period (2 percent, P = 0.017).
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

^ Therefore the induction of IEG expression might reflect behavioral depression rather than the behavioral stimulation that is the basis for the widespread human use of caffeine.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ This could indicate that the decrease in caloric intake noted above (Section IVF) might be an effect of acute rather than long-term caffeine use.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

The extraction process is simple: CO2 is forced through the green coffee beans at temperatures above 31.1 °C and pressures above 73 atm. .Under these conditions, CO2 is in a "supercritical" state: It has gaslike properties that allow it to penetrate deep into the beans but also liquid-like properties that dissolve 97–99% of the caffeine.^ I would like to simply do a copy-and-paste of these pre-saved searches into Google's front page search screen.

^ It cannot be excluded that caffeine might have analgesic properties for specific types of pain, which may be the case for headache ( Ward et al., 1991 ), which is significantly and dose-dependently reduced by caffeine under double-blind conditions.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ Conversely, liking for the taste and aroma of coffee might be acquired through the process of classical conditioning, involving association of these orosensory cues with the psychopharmacological consequences of caffeine ingestion.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

.The caffeine-laden CO2 is then sprayed with high pressure water to remove the caffeine.^ A regression analysis on maternal depression suggested that 28% of the variance was explained by low support scale scores, not co-sleeping with their infant and high caffeine intake.
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The caffeine can then be isolated by charcoal adsorption (as above) or by distillation, recrystallization, or reverse osmosis.[117]

Extraction by organic solvents

.Organic solvents such as ethyl acetate present much less health and environmental hazard than previously used chlorinated and aromatic solvents.^ Accordingly, the overall activity of the nucleus accumbens is much less affected by caffeine than by cocaine, nicotine, and amphetamine.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ Exsmokers use more coffee than nonsmokers but somewhat less than smokers.
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^ The reinforcing properties of caffeine are, however, very much weaker and less consistent than those of cocaine and amphetamine.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

.Another method is to use triglyceride oils obtained from spent coffee grounds.^ Methods: Data on oral contraceptive use, habitual coffee consumption and smoking habits were obtained from 100 Serbian and 149 Swedish healthy volunteers using a detailed questionnaire.
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^ Using this method, the reward values of cigarettes and coffee were compared ( Bickel et al., 1992 ).
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

Religion

.Some Latter-day Saints (Mormons), Seventh-day Adventists, Church of God (Restoration) adherents, and Christian Scientists[118] do not consume caffeine.^ Secondary analyses of data collected after a day of normal caffeine consumption were also carried out to examine some alternative explanations of their results which showed effects of caffeine after a day of normal caffeine consumption.
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^ The odds ratio for patients to develop postoperative headache amounted to 5.0 for those consuming more than 400 mg/day caffeine and to 3.7 for those operated after noon on the following day.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

.A few followers from these religions believe that one is not supposed to consume a non-medical, psychoactive substance, or believe that one is not supposed to consume a substance that is addictive.^ Participants rated legal sanctions against pregnant women who used one of these substances and risk potential for developing children.
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^ Caffeine is one of the most widely consumed psychoactive substances in the world and is ingested in a variety of favorites, such as coffee, tea, cola and so on.
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.The Church of Jesus Christ of Latter-day Saints has said the following with regard to caffeinated beverages: “With reference to cola drinks, the Church has never officially taken a position on this matter, but the leaders of the Church have advised, and we do now specifically advise, against the use of any drink containing harmful drugs under circumstances that would result in acquiring the habit.^ Indeed, not less than 14% of all erstwhile consumers in Vermont had stopped the intake of all caffeine-containing beverages largely for this reason ( Hughes and Oliveto, 1997 ).
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ In another study ( Lane, 1996 ) it was found that the rate of smoking was higher during such periods of the day when caffeine-containing beverages were consumed than during other parts of the day.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ The results indicated that the expectation of receiving caffeine was sufficient to counteract the impairment of intentional control seen under alcohol.
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.Any beverage that contains ingredients harmful to the body should be avoided.” (Priesthood Bulletin, Feb.^ Objective: To test whether consumption of a beverage containing active ingredients will increase 24-hour energy metabolism in healthy, young, lean individuals.
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1972, p. 4.) See also Word of Wisdom.
.Gaudiya Vaishnava Hindus generally also abstain from caffeine, as it is alleged to cloud the mind and over-stimulate the senses.^ As already noted, psychomotor stimulants do not readily generalize to caffeine ( Chait and Johanson, 1988 ).
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

.To be initiated under a guru, one must have had no caffeine (along with alcohol, nicotine and other drugs) for at least a year.^ The results indicated that the expectation of receiving caffeine was sufficient to counteract the impairment of intentional control seen under alcohol.
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^ In one session, subjects received caffeine (2.5 mg/kg bodyweight), while in the other they received placebo.
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^ The patients (N = 94) were assessed for their intake of alcohol, nicotine, and caffeine, and then treated openly for 8 weeks with 20 mg/day of fluoxetine.
  • Psychopharmacology of Caffeine. 15 September 2009 6:10 UTC www.psycom.net [Source type: Academic]

.In Islam the main rule on caffeine is that it is permissible, however it is worth noting that it should not be overused and can cause severe harm to one's body.^ However, not everyone agrees that such a correction based on the metabolic body weight should be applied.
  • Actions of Caffeine in the Brain with Special Reference to Factors That Contribute to Its Widespread Use — Pharmacological Reviews 19 January 2010 8:49 UTC pharmrev.aspetjournals.org [Source type: Academic]

^ The caffeine-caused reduction of cell cycle effects was also observed in several other cancer chemotherapeutic agents, including bleomycin and Adriamycin.
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^ However, caffeine and sugar are present in amounts known to cause a variety of adverse health effects.
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With regard to the caffeine in coffee, Imam Shihab al-Din said: 'it is halal (lawful) to drink, because all things are halal (lawful) except that which God has made haraam (unlawful)'.[119]

See also

References

  1. ^ This is the pKa for protonated caffeine, given as a range of values included in Harry G. Brittain, Richard J. Prankerd (2007). Profiles of Drug Substances, Excipients and Related Methodology, volume 33: Critical Compilation of Pka Values for Pharmaceutical Substances. Academic Press. ISBN 012260833X. http://books.google.co.jp/books?id=D3vBu5Tx4XwC&pg=PT15&lpg=PT15. 
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  117. ^ a b Senese, Fred (2005-09-20). "How is coffee decaffeinated?". General Chemistry Online. http://antoine.frostburg.edu/chem/senese/101/consumer/faq/decaffeinating-coffee.shtml. Retrieved 2009-08-03. 
  118. ^ "Voices of Faith: April 12, 2008". http://www.redding.com/news/2008/Apr/12/voices-faith-april-12-2008/. Retrieved 2009-08-03. 
  119. ^ "Drinking drinks with caffeine". http://islamweb.net/ver2/Fatwa/ShowFatwa.php?lang=E&Id=84417&Option=FatwaId. Retrieved 2009-08-03. 

External links

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Health


1911 encyclopedia

Up to date as of January 14, 2010

From LoveToKnow 1911

.CAFFEINE, or Theine (1.3.7 trimethyl 2.6 dioxypurin), C8 Hio N4 02.112 0, a substance found in the leaves and beans of the coffee tree, in tea, in Paraguay tea, and in small quantities in cocoa and in the kola nut.^ In 1838, it was found that theine, a substance in tea, was identical to caffeine.
  • Bodybuilding.com - Caffeine Information and Product Listing! Caffeine FAQ! 15 September 2009 6:10 UTC www.bodybuilding.com [Source type: FILTERED WITH BAYES]

^ It is found in the leaves and beans of the coffee plant, in tea, yerba mate, and guarana berries, and in small quantities in cocoa, the kola nut and the Yaupon Holly.
  • Caffeine -- History, Chemical and Physical Properties and Effects 19 January 2010 8:49 UTC www.scienceofcooking.com [Source type: Academic]

^ The most commonly known sources of caffeine are coffee and cocoa beans, kola nuts and tea leaves.
  • Caffeine & Health: Clarifying The Controversies 19 January 2010 8:49 UTC www.afic.org [Source type: Academic]

.It may be extracted from tea or coffee by boiling with water, the dissolved tannin precipitated by basic lead acetate, the solution filtered, excess of lead precipitated by sulphuretted hydrogen and the filtered liquid then evaporated to crystallization; or, tea is boiled with water, and the whole then evaporated to a syrup, which is mixed with slaked lime, evaporated to dryness on the water-bath and extracted with chloroform (P. Cazeneuve, Bull.^ This precipitation is not due to the caffeine in coffee or tea.
  • Alcohol & Drug Abuse: Caffeine and Schizophrenia -- Hughes et al. 49 (11): 1415 -- Psychiatr Serv 19 January 2010 8:49 UTC psychservices.psychiatryonline.org [Source type: Academic]

^ It is most commonly consumed by humans in infusions extracted from the cherries of the coffee plant and the leaves of the tea bush, as well as from...
  • Caffeine - Kosmix : Reference, Videos, Images, News, Shopping and more... 19 January 2010 8:49 UTC health.kosmix.com [Source type: FILTERED WITH BAYES]

^ Some drip coffee makers require periodic cleansing with a solution of water and vinegar.
  • Coffee and Caffeine FAQ 15 September 2009 6:10 UTC www.nootropics.com [Source type: FILTERED WITH BAYES]
  • Coffee and Caffeine's Frequently Asked Questions 19 January 2010 8:49 UTC www.faqs.org [Source type: FILTERED WITH BAYES]
  • Frequently Asked Questions about Coffee and Caffeine 19 January 2010 8:49 UTC www.indwes.edu [Source type: FILTERED WITH BAYES]

de la soc. chim. de Paris,
1876-1877, 2 7, p. 1 99). .Synthetically it may be prepared by the methylation of silver theobromine and silver theophyllin or by boiling heteroxanthine with methyl iodide and potash.^ The weak stimulant effect of chocolate may be due to a combination of theobromine and theophylline as well as caffeine.

^ Caffeine 1,3,7-trimethylxanthine Theophylline 1,3-dimethylxanthine Theobromine 3,7-dimethylxanthine Coffee and tea contain caffeine and theophylline, respectively, which are methylated purine derivatives that inhibit cAMP phosphodiesterase.
  • Frequently Asked Questions about Caffeine 15 September 2009 6:10 UTC www.sweetmarias.com [Source type: FILTERED WITH BAYES]
  • Coffee and Caffeine FAQ 15 September 2009 6:10 UTC www.nootropics.com [Source type: FILTERED WITH BAYES]
  • Coffee and Caffeine's Frequently Asked Questions 19 January 2010 8:49 UTC www.faqs.org [Source type: FILTERED WITH BAYES]
  • Frequently Asked Questions about Coffee and Caffeine 19 January 2010 8:49 UTC www.indwes.edu [Source type: FILTERED WITH BAYES]

^ Theobromine and theophylline are two dimethylxanthines that have two rather than three methyl groups.
  • Frequently Asked Questions about Caffeine 15 September 2009 6:10 UTC www.sweetmarias.com [Source type: FILTERED WITH BAYES]
  • Coffee and Caffeine FAQ 15 September 2009 6:10 UTC www.nootropics.com [Source type: FILTERED WITH BAYES]
  • Coffee and Caffeine's Frequently Asked Questions 19 January 2010 8:49 UTC www.faqs.org [Source type: FILTERED WITH BAYES]
  • Frequently Asked Questions about Coffee and Caffeine 19 January 2010 8:49 UTC www.indwes.edu [Source type: FILTERED WITH BAYES]

E. Fischer and L. Ach (Berichte, 18 95, 28, p. 3 1 35) have synthesized it from dimethyl alloxan, whilst W. Traube (Berichte, 1900, 33, p. 3435) has obtained it from 1.3 diamethyl 4.5 diamino 2.6 dioxypyrimidine. On the constitution of caffeine see Purin and also E. Fischer (Annalen, 1882, 215, p. 253).
.Caffeine crystallizes in long silky needles, which are slightly soluble in cold water.^ Caffeine is soluble in both water & oil and can readily cross the blood-brain barrier.
  • IS CAFFEINE A HEALTH HAZARD ? 15 September 2009 6:10 UTC www.benbest.com [Source type: Academic]

^ Caffeine is moderately soluble in water and therefore can be found in the body wherever there is water-which is in most places.
  • Caffeine 19 January 2010 8:49 UTC www.herbs2000.com [Source type: FILTERED WITH BAYES]

^ Soluble in water or alcohol with hydrolysis into caffeine and acetic acid.
  • Frequently Asked Questions about Caffeine 15 September 2009 6:10 UTC www.sweetmarias.com [Source type: FILTERED WITH BAYES]
  • Coffee and Caffeine's Frequently Asked Questions 19 January 2010 8:49 UTC www.faqs.org [Source type: FILTERED WITH BAYES]
  • Frequently Asked Questions about Coffee and Caffeine 19 January 2010 8:49 UTC www.indwes.edu [Source type: FILTERED WITH BAYES]

It becomes anhydrous at 100 C. and melts at 234° to 235° C. It has a faint bitter taste and gives salts with mineral acids. .On oxidation with nitric acid caffeine gives cholesterophane (dimethyl parabanic acid), but if chlorine water be used as the oxidant, then it yields monomethyl urea and dimethyl alloxan (E. Fischer).^ Parents should use common sense in deciding how much caffeine-containing foods or beverages they give their children, as with many foods.
  • Caffeine 1 19 January 2010 8:49 UTC www.lowcarb.org [Source type: Academic]

^ Soluble in water or alcohol with hydrolysis into caffeine and acetic acid.
  • Frequently Asked Questions about Caffeine 15 September 2009 6:10 UTC www.sweetmarias.com [Source type: FILTERED WITH BAYES]
  • Coffee and Caffeine's Frequently Asked Questions 19 January 2010 8:49 UTC www.faqs.org [Source type: FILTERED WITH BAYES]
  • Frequently Asked Questions about Coffee and Caffeine 19 January 2010 8:49 UTC www.indwes.edu [Source type: FILTERED WITH BAYES]

^ For low to moderate intensity activities Caffeine has been shown to stimulate the use of stored fat (free fatty acids).
  • Caffeine and Endurance | Team First Endurance Blog 19 January 2010 8:49 UTC blog.firstendurance.com [Source type: Academic]



Simple English

Caffeine is a drug (or chemical) that is found in plants. In large amounts it can kill humans and other animals. Even small amounts can kill some animals, such as dogs.

Contents

Where caffeine is from

Caffeine is the main drug that is in coffee. Coffee comes from a tree. The seeds of the tree are roasted to make coffee.

Caffeine comes from other plants as well. It is found in guarana, yerba maté, cacao, and some plants used to make tea. The plants use caffeine as a pesticide. This is a chemical that kills insects if they eat the plant. It is the way the plant protects itself.

It is called guaranine when it comes from the guarana plant and theine when it comes from a tea plant. It is called mateine in the mate drink. This drink is an infusion made with Yerba mate.

What caffeine is

Caffeine is a stimulant drug. A stimulant is a drug that increases body actions like heart rate, blood pressure, and metabolism. It makes a person feel more awake and alert.

Caffeine also is a diuretic. This means it makes a person make more urine (the waste liquid a person makes).

The caffeine chemical is called a xanthine alkaloid. This is a group of chemicals that are stimulants. Some xanthine alkaloids (like theophylline) are used to help asthma.

What caffeine is used for

The biggest use of caffeine is as a stimulant. People drink coffee and other drinks with caffeine to stay awake.

Doctors sometimes use caffeine as a medicine. It is used for headaches (head pain). It is sometimes used to help premature (born very early) babies to breathe. The short-term risk of this treatment seems to be that the babies treated gain less weight than usual.[1]

Caffeine is sometimes given to people after a lumbar puncture. This is a test to see if someone has meningitis.'''

In the beginning caffeine was found to relieve hunger, so it was used for weight loss. That did not last because people were using too much. Caffeine can be a very dangerous drug when not used in the right way.

Caffeine also has medicinal properties. It is used in many over the counter medicines, such as Excedrin, Midol and Anacin. When combined with other analgesics, caffeine can help to alleviate headaches and cramps.

Problems with caffeine

File:Caffeinated
Caffeine is a problem for spiders. The image above shows a spiderweb which was woven by a normal spider. The image below shows a web of a spider that had received Caffeine in an experiment

The largest problem with caffeine is addiction. This is when people get bad symptoms when they do not have the drug. When people have withdrawal (feel bad because they do not have the drug) they drink more. This makes them feel better. But if they cannot get more, they are likely to feel some of the symptoms listed below:

  • Headache
  • Being tired or need to sleep
  • Feeling irritable
  • Nausea (feeling like vomiting)

Caffeine can also hurt people if they drink very much at once. If someone takes very much of a drug at once it is called an overdose. Caffeine overdose is a medical diagnosis. It is called:Caffeine-Induced Organic Mental Disorder or Caffeine Intoxication. People with this can have these symptoms:

  • Very bad feelings like:
    • Paranoia (feeling as if people are about to hurt the person)
    • Restlessness or nervousness (with the person feeling like he cannot sit down or rest)
    • Anxiety (very bad worry)
  • Muscle movements that cannot be stopped
  • Very fast heart rate
  • Abnormal heart rhythms (even heart stopping)
  • Very high blood pressure
  • Vomiting
  • Confusion (not knowing who the person is or where he/she is)

How much caffeine is safe

250-300 mg of caffeine a day is a moderate amount. That is as much caffeine that is in three cups of coffee (8oz each cup). More than 750-1000mg a day is dangerous, but people who drink more coffee every day can drink more without getting sick. The Lethal Dose 50 of caffeine is 192 mg per kilogram, in rats. In humans, it is between 150 and 200 mg per kilogram.

Caffeine is in many drinks and foods. This is approximate amounts of caffeine in some food and drink:

  • Brewed coffee - 40 to 220 mg in a cup
  • Instant coffee - 30 to 120 mg in a cup
  • Decaffeinated coffee (with much caffeine taken out) - 3 to 5 mg in a cup
  • Tea - 20 to 110 mg in a cup
  • Soda drinks with caffeine - 36 to 90 mg in 12 ounces. Some people think that soft drinks which are light in color do not contain caffeine. This is not always true.
  • Milk chocolate - 3 to 6 mg in an ounce
  • Bittersweet chocolate - 25 mg in an ounce

One ounce – abbreviated oz - is 30ml.

A 'cup' is 8 oz (240ml.)

Different ways to get 200mg of caffeine

Caffeine equivalents[2][3]
In general, each of the following contains approximately 200 milligrams of caffeine:

Notes:

A fluid ounce is between 28 and 30 mililitres.

a. There may also be large amounts of other chemicals, similar to caffeine in Chocolate and other products of cacao. There is theobromine in cacao, for example. These substances can have effects similar to those of caffeine.

b. Most tea drunk in North America is not very strong. The figures are for this kind of tea. The tea drunk in most other places of the world is stronger; for these kinds of tea, the figures are probably too small.

References

  1. Schmidt, B; Roberts, RS, Davis, P, Doyle, LW, et al (May 18 2006). [Expression error: Unexpected < operator "Caffeine therapy for apnea of prematurity"]. N Engl J Med 354 (20): 2112–21. 
  2. "Caffeine Content of Food and Drugs". Nutrition Action Health Newsletter. Center for Science in the Public Interest. December 1996. Archived from the original on 2007-06-14. http://web.archive.org/web/20070614144016/http://www.cspinet.org/nah/caffeine/caffeine_content.htm. Retrieved 2006-08-22. 
  3. "Caffeine Content of Beverages, Foods, & Medications". The Vaults of Erowid. July 7 2006. http://www.erowid.org/chemicals/caffeine/caffeine_info1.shtml. Retrieved 2006-08-22. 

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