From Wikipedia, the free encyclopedia

Herbalism is a traditional medicinal or folk medicine practice based on the use of plants and plant extracts. Herbalism is also known as botanical medicine, medical herbalism, herbal medicine, herbology, and phytotherapy. The scope oxcxf herbal medicine is sometimes extended to include fungal and bee products, as well as minerals, shells and certain animal parts^[1].

Many plants synthesize substances that are useful to the maintenance of health in humans and other animals. These include aromatic substances, most of which are phenols or their oxygen-substituted derivatives such as tannins. Many are secondary metabolites, of which at least 12,000 have been isolated — a number estimated to be less than 10% of the total. In many cases, substances such as alkaloids serve as plant defense mechanisms against predation by microorganisms, insects, and herbivores. Many of the herbs and spices used by humans to season food yield useful medicinal compounds.^[2][3]

Despite the increased popularity of herbal treatments, the safety and effectiveness of alternative medicines have not been scientifically corroborated^[4] and remain largely unknown.^[5]. A number of herbs are thought to be likely to cause adverse effects^[4]. Furthermore, "adulteration, inappropriate formulation, or lack of understanding of plant and drug interactions have led to adverse reactions that are sometimes life threatening or lethal^[6]." Herbalists are often trained to take well-established risks into consideration when patients consult them.

Anthropology of herbalism

People on all continents have used hundreds to thousands of indigenous plants for treatment of ailments since prehistoric times. Medicinal herbs were found in the personal effects of an "ice man", whose body was frozen in the Swiss Alps for more than 5,300 years. These herbs appear to have been used to treat the parasites found in his intestines. Anthropology or anthropologists theorize that animals evolved a tendency to seek out bitter plant parts in response to illness.

Indigenous healers often claim to have learned by observing that sick animals change their food preferences to nibble at bitter herbs they would normally reject.^[7] Field biologists have provided corroborating evidence based on observation of diverse species, such as chimpanzees, chickens, sheep and butterflies. Lowland gorillas take 90% of their diet from the fruits of Aframomum melegueta, a relative of the ginger plant, that is a potent antimicrobial and apparently keeps shigellosis and similar infections at bay.^[8]

Researchers from Ohio Wesleyan University found that some birds select nesting material rich in antimicrobial agents which protect their young from harmful bacteria.^[9]

Sick animals tend to forage plants rich in secondary metabolites, such as tannins and alkaloids.^[10] Since these phytochemicals often have antiviral, antibacterial, antifungal and antihelminthic properties, a plausible case can be made for self-medication by animals in the wild.^[8]

Some animals have digestive systems especially adapted to cope with certain plant toxins. For example, the koala can live on the leaves and shoots of the eucalyptus, a plant that is dangerous to most animals.^[11] A plant that is harmless to a particular animal may not be safe for humans to ingest.^[12] A reasonable conjecture is that these discoveries were traditionally collected by the medicine people of indigenous tribes, who then passed on safety information and cautions.

The use of herbs and spices in cuisine developed in part as a response to the threat of food-borne pathogens. Studies show that in tropical climates where pathogens are the most abundant, recipes are the most highly spiced. Further, the spices with the most potent antimicrobial activity tend to be selected.^[13] In all cultures vegetables are spiced less than meat, presumably because they are more resistant to spoilage.^[14]

Herbs in history

Borage from Project Gutenberg EBook of Culinary Herbs: Their Cultivation Harvesting Curing and Uses, by M. G. Kains

In the written record, the study of herbs dates back over 5,000 years to the Sumerians, who described well-established medicinal uses for such plants as laurel, caraway, and thyme. Ancient Egyptian medicine of 1000 B.C. are known to have used garlic, opium, castor oil, coriander, mint, indigo, and other herbs for medicine and the Old Testament also mentions herb use and cultivation, including mandrake, vetch, caraway, wheat, barley, and rye.

Indian Ayurveda medicine has used herbs such as turmeric possibly as early as 1900 B.C.^[15] Many other herbs and minerals used in Ayurveda were later described by ancient Indian herbalists such as Charaka and Sushruta during the 1st millenium BC. The Sushruta Samhita attributed to Sushruta in the 6th century BC describes 700 medicinal plants, 64 preparations from mineral sources, and 57 preparations based on animal sources.^[16]

The first Chinese herbal book, the Shennong Bencao Jing, compiled during the Han Dynasty but dating back to a much earlier date, possibly 2700 B.C., lists 365 medicinal plants and their uses - including ma-Huang, the shrub that introduced the drug ephedrine to modern medicine. Succeeding generations augmented on the Shennong Bencao Jing, as in the Yaoxing Lun (Treatise on the Nature of Medicinal Herbs), a 7th century Tang Dynasty treatise on herbal medicine.

The ancient Greeks and Romans made medicinal use of plants. Greek and Roman medicinal practices, as preserved in the writings of Hippocrates and - especially - Galen, provided the pattern for later western medicine. Hippocrates advocated the use of a few simple herbal drugs - along with fresh air, rest, and proper diet. Galen, on the other hand, recommended large doses of drug mixtures - including plant, animal, and mineral ingredients. The Greek physician compiled the first European treatise on the properties and uses of medicinal plants, De Materia Medica. In the first century AD, Dioscorides wrote a compendium of more than 500 plants that remained an authoritative reference into the 17th century. Similarly important for herbalists and botanists of later centuries was the Greek book that founded the science of botany, Theophrastus’ Historia Plantarum, written in the fourth century B.C.

Thyme from Project Gutenberg EBook of Culinary Herbs: Their Cultivation Harvesting Curing and Uses, by M. G. Kains

Middle Ages

The uses of plants for medicine and other purposes changed little in early medieval Europe. Many Greek and Roman writings on medicine, as on other subjects, were preserved by hand copying of manuscripts in monasteries. The monasteries thus tended to become local centers of medical knowledge, and their herb gardens provided the raw materials for simple treatment of common disorders. At the same time, folk medicine in the home and village continues uninterrupted, supporting numerous wandering and settled herbalists. Among these were the “wise-women,” who prescribed herbal remedies often along with spells and enchantments. It was not until the late Middle Ages that women who were knowledgeable in herb lore became the targets of the witch hysteria. One of the most famous women in the herbal tradition was Hildegard of Bingen. A twelfth century Benedictine nun, she wrote a medical text called Causes and Cures.

Medical schools known as Bimaristan began to appear from the 9th century in the medieval Islamic world, which was generally more advanced than medieval Europe at the time. The Arabs venerated Greco-Roman culture and learning, and translated tens of thousands of texts into Arabic for further study.^[17] As a trading culture, the Arab travellers had access to plant material from distant places such as China and India. Herbals, medical texts and translations of the classics of antiquity filtered in from east and west.^[18] Muslim botanists and Muslim physicians significantly expanded on the earlier knowledge of materia medica. For example, al-Dinawari described more than 637 plant drugs in the 9th century,^[19] and Ibn al-Baitar described more than 1,400 different plants, foods and drugs, over 300 of which were his own original discoveries, in the 13th century.^[20] The experimental scientific method was introduced into the field of materia medica in the 13th century by the Andalusian-Arab botanist Abu al-Abbas al-Nabati, the teacher of Ibn al-Baitar. Al-Nabati introduced empirical techniques in the testing, description and identification of numerous materia medica, and he separated unverified reports from those supported by actual tests and observations. This allowed the study of materia medica to evolve into the science of pharmacology.^[21]

Avicenna's The Canon of Medicine (1025) is considered the first pharmacopoeia,^[22][23] and lists 800 tested drugs, plants and minerals.^[24] Book Two is devoted to a discussion of the healing properties of herbs, including nutmeg, senna, sandalwood, rhubarb, myrrh, cinammon, and rosewater.^[17] Baghdad was an important center for Arab herbalism, as was Al-Andalus between 800 and 1400. Abulcasis (936-1013) of Cordoba authored The Book of Simples, an important source for later European herbals, while Ibn al-Baitar (1197-1248) of Malaga authored the Corpus of Simples, the most complete Arab herbal which introduced 200 new healing herbs, including tamarind, aconite, and nux vomica.^[17][25] Other pharmacopoeia books include that written by Abu-Rayhan Biruni in the 11th century^[23] and Ibn Zuhr (Avenzoar) in the 12th century (and printed in 1491),^[26] The origins of clinical pharmacology also date back to the Middle Ages in Avicenna's The Canon of Medicine, Peter of Spain's Commentary on Isaac, and John of St Amand's Commentary on the Antedotary of Nicholas.^[27] In particular, the Canon introduced clinical trials,^[28] randomized controlled trials,^[29][30] and efficacy tests.^[31][32]

Alongside the university system, folk medicine continued to thrive. The continuing importance of herbs for the centuries following the Middle Ages is indicated by the hundreds of herbals published after the invention of printing in the fifteenth century. Theophrastus’ Historia Plantarum was one of the first books to be printed, but Dioscorides’ De Materia Medica, Avicenna's Canon of Medicine and Avenzoar's pharmacopoeia were not far behind.

Marjoram from Project Gutenberg EBook of Culinary Herbs: Their Cultivation Harvesting Curing and Uses, by M. G. Kains

Modern era

The fifteenth, sixteenth, and seventeenth centuries were the great age of herbals, many of them available for the first time in English and other languages rather than Latin or Greek. The first herbal to be published in English was the anonymous Grete Herball of 1526. The two best-known herbals in English were The Herball or General History of Plants (1597) by John Gerard and The English Physician Enlarged (1653) by Nicholas Culpeper. Gerard’s text was basically a pirated translation of a book by the Belgian herbalist Dodoens and his illustrations came from a German botanical work. The original edition contained many errors due to faulty matching of the two parts. Culpeper’s blend of traditional medicine with astrology, magic, and folklore was ridiculed by the physicians of his day yet his book - like Gerard’s and other herbals - enjoyed phenomenal popularity. The Age of Exploration and the Columbian Exchange introduced new medicinal plants to Europe. The Badianus Manuscript was an illustrated Aztec herbal translated into Latin in the 16th century.

The second millennium, however, also saw the beginning of a slow erosion of the pre-eminent position held by plants as sources of therapeutic effects. This began with the Black Death, which the then dominant Four Element medical system proved powerless to stop. A century later, Paracelsus introduced the use of active chemical drugs (like arsenic, copper sulfate, iron, mercury, and sulfur). These were accepted even though they had toxic effects because of the urgent need to treat Syphilis. The rapid development of chemistry and the other physical sciences, led increasingly to the dominance of chemotherapy - chemical medicine - as the orthodox system of the twentieth century.

Role of herbal medicine in modern human society

Botánicas, such as this one in Jamaica Plain, Massachusetts, cater to the Latino community and sell herbal cures and folk medicine alongside statues of saints, candles decorated with prayers, lucky bamboo, and other items.

The use of herbs to treat disease is almost universal among non-industrialized societies.^[33] A number of traditions came to dominate the practice of herbal medicine at the end of the twentieth century:

• The "classical" herbal medicine system, based on Greek and Roman sources
• The Siddha and Ayurvedic medicine systems from various South Asian Countries
• Chinese herbal medicine (Chinese herbology) 中药 (zhōngyào)
• Unani-Tibb medicine
• Shamanic herbalism: a catch-all phrase for information mostly supplied from South America and the Himalayas

Many of the pharmaceuticals currently available to physicians have a long history of use as herbal remedies, including opium, aspirin, digitalis, and quinine. The World Health Organization (WHO) estimates that 80 percent of the world's population presently uses herbal medicine for some aspect of primary health care.^[34] Pharmaceuticals are prohibitively expensive for most of the world's population, half of which lives on less than $2 U.S. per day.^{[35][36][37][38]} In comparison, herbal medicines can be grown from seed or gathered from nature for little or no cost. Herbal medicine is a major component in all traditional medicine systems, and a common element in Siddha, Ayurvedic, homeopathic, naturopathic, traditional Chinese medicine, and Native American medicine.

The use of, and search for, drugs and dietary supplements derived from plants have accelerated in recent years. Pharmacologists, microbiologists, botanists, and natural-products chemists are combing the Earth for phytochemicals and leads that could be developed for treatment of various diseases. In fact, according to the World Health Organisation, approximately 25% of modern drugs used in the United States have been derived from plants.^[39]

• Three quarters of plants that provide active ingredients for prescription drugs came to the attention of researchers because of their use in traditional medicine.^[40]
• Among the 120 active compounds currently isolated from the higher plants and widely used in modern medicine today, 80 percent show a positive correlation between their modern therapeutic use and the traditional use of the plants from which they are derived.^[41]
• More than two thirds of the world's plant species - at least 35,000 of which are estimated to have medicinal value - come from the developing countries.
• At least 7,000 medical compounds in the modern pharmacopoeia are derived from plants^[42]

Biological background

The anthocyanins in sweet violets produce deep red, violet and blue shades.

The carotenoids in primrose produce bright red, yellow and orange shades.

All plants produce chemical compounds as part of their normal metabolic activities. These are arbitrarily divided into primary metabolites, such as sugars and fats, found in all plants, and secondary metabolites, compounds not essential for basic function found in a smaller range of plants, some useful ones found only in a particular genus or species. Pigments harvest light, protect the organism from radiation and display colors to attract pollinators. Many common weeds, such as nettle, dandelion and chickweed, have medicinal properties.^[43][44]

The functions of secondary metabolites are varied. For example, some secondary metabolites are toxins used to deter predation, and others are pheromones used to attract insects for pollination. Phytoalexins protect against bacterial and fungal attacks. Allelochemicals inhibit rival plants that are competing for soil and light.

Plants upregulate and downregulate their biochemical paths in response to the local mix of herbivores, pollinators and microorganisms.^[45] The chemical profile of a single plant may vary over time as it reacts to changing conditions. It is the secondary metabolites and pigments that can have therapeutic actions in humans and which can be refined to produce drugs.

Plants synthesize a bewildering variety of phytochemicals but most are derivatives of a few biochemical motifs.

• Alkaloids contain a ring with nitrogen. Many alkaloids have dramatic effects on the central nervous system. Caffeine is an alkaloid that provides a mild lift but the alkaloids in datura cause severe intoxication and even death.
• Phenolics contain phenol rings. The anthocyanins that give grapes their purple color, the isoflavones, the phytoestrogens from soy and the tannins that give tea its astringency are phenolics.
• Terpenoids are built up from terpene building blocks. Each terpene consists of two paired isoprenes. The names monoterpenes, sesquiterpenes, diterpenes and triterpenes are based on the number of isoprene units. The fragrance of rose and lavender is due to monoterpenes. The carotenoids produce the reds, yellows and oranges of pumpkin, corn and tomatoes.
• Glycosides consist of a glucose moiety attached to an aglycone. The aglycone is a molecule that is bioactive in its free form but inert until the glycoside bond is broken by water or enzymes. This mechanism allows the plant to defer the availability of the molecule to an appropriate time, similar to a safety lock on a gun. An example is the cyanoglycosides in cherry pits that release toxins only when bitten by a herbivore.

The word drug itself comes from the Dutch word "droog" (via the French word Drogue), which means 'dried plant'. Some examples are inulin from the roots of dahlias, quinine from the cinchona, morphine and codeine from the poppy, and digoxin from the foxglove.

The active ingredient in willow bark, once prescribed by Hippocrates, is salicin, which is converted in the body into salicylic acid. The discovery of salicylic acid would eventually lead to the development of the acetylated form acetylsalicylic acid, also known as "aspirin", when it was isolated from a plant known as meadowsweet. The word aspirin comes from an abbreviation of meadowsweet's Latin genus Spiraea, with an additional "A" at the beginning to acknowledge acetylation, and "in" was added at the end for easier pronunciation.^[46] "Aspirin" was originally a brand name, and is still a protected trademark in some countries. This medication was patented by Bayer AG.

Herbal philosophy

Rosemary

Four approaches to the use of plants as medicine include:

1. The magical/shamanic

Almost all non-modern societies recognise this kind of use. The practitioner is regarded as endowed with gifts or powers that allow him/her to use herbs in a way that is hidden from the average person, and the herbs are said to affect the spirit or soul of the person.

2. The energetic

This approach includes the major systems of TCM, Ayurveda, and Unani. Herbs are regarded as having actions in terms of their energies and affecting the energies of the body. The practitioner may have extensive training, and ideally be sensitive to energy, but need not have supernatural powers.

3. The functional dynamic

This approach was used by early physiomedical practitioners, whose doctrine forms the basis of contemporary practice in the UK. Herbs have a functional action, which is not necessarily linked to a physical compound, although often to a physiological function, but there is no explicit recourse to concepts involving energy.

4. The chemical

Modern practitioners - called Phytotherapists - attempt to explain herb actions in terms of their chemical constituents. It is generally assumed that the specific combination of secondary metabolites in the plant are responsible for the activity claimed or demonstrated, a concept called synergy.

Most modern herbalists concede that pharmaceuticals are more effective in emergency situations where time is of the essence. An example would be where a patient had an acute heart attack that posed imminent danger. However they claim that over the long term herbs can help the patient resist disease, and that in addition, they provide nutritional and immunological support that pharmaceuticals lack. They view their goal as prevention as well as cure.

Herbalists tend to use extracts from parts of plants, such as the roots or leaves but not isolate particular phytochemicals.^[47] Pharmaceutical medicine prefers single ingredients on the grounds that dosage can be more easily quantified. It is also possible to patent single compounds, and therefore generate income. Herbalists often reject the notion of a single active ingredient, arguing that the different phytochemicals present in many herbs will interact to enhance the therapeutic effects of the herb and dilute toxicity.^[48] Furthermore, they argue that a single ingredient may contribute to multiple effects. Herbalists deny that herbal synergism can be duplicated with synthetic chemicals. They argue that phytochemical interactions and trace components may alter the drug response in ways that cannot currently be replicated with a combination of a few putative active ingredients.^[49][50] Pharmaceutical researchers recognize the concept of drug synergism but note that clinical trials may be used to investigate the efficacy of a particular herbal preparation, provided the formulation of that herb is consistent.^[51]

Thai chili peppers contain capsaicin

In specific cases the claims of synergy^[52] and multifunctionality^[53] have been supported by science. The open question is how widely both can be generalized. Herbalists would argue that cases of synergy can be widely generalized, on the basis of their interpretation of evolutionary history, not necessarily shared by the pharmaceutical community. Plants are subject to similar selection pressures as humans and therefore they must develop resistance to threats such as radiation, reactive oxygen species and microbial attack in order to survive.^[54] Optimal chemical defenses have been selected for and have thus developed over millions of years.^[55] Human diseases are multifactorial and may be treated by consuming the chemical defences that they believe to be present in herbs. Bacteria, inflammation, nutrition and ROS (reactive oxygen species) may all play a role in arterial disease.^[56] Herbalists claim a single herb may simultaneously address several of these factors. Likewise a factor such as ROS may underlie more than one condition.^[57] In short herbalists view their field as the study of a web of relationships rather than a quest for single cause and a single cure for a single condition.

In selecting herbal treatments herbalists may use forms of information that are not applicable to pharmacists. Because herbs can moonlight as vegetables, teas or spices they have a huge consumer base and large-scale epidemiological studies become feasible. Ethnobotanical studies are another source of information.^[58] For example, when indigenous peoples from geographically dispersed areas use closely related herbs for the same purpose that is taken as supporting evidence for its efficacy. Herbalists contend that historical medical records and herbals are underutilized resources.^[59] They favor the use of convergent information in assessing the medical value of plants. An example would be when in-vitro activity is consistent with traditional use.

Popularity

A survey released in May 2004 by the National Center for Complementary and Alternative Medicine focused on who used complementary and alternative medicines (CAM), what was used, and why it was used. The survey was limited to adults, aged 18 years and over during 2002, living in the United States.

According to this survey, herbal therapy, or use of natural products other than vitamins and minerals, was the most commonly used CAM therapy (18.9%) when all use of prayer was excluded.^[60][61]

Herbal remedies are very common in Europe. In Germany, herbal medications are dispensed by apothecaries (e.g., Apotheke). Prescription drugs are sold alongside essential oils, herbal extracts, or herbal teas. Herbal remedies are seen by some as a treatment to be preferred to pure medical compounds which have been industrially produced.^[62]

In the United Kingdom, the training of medical herbalists is done by state funded Universities. For example, Bachelor of Science degrees in herbal medicine are offered at Universities such as University of East London, Middlesex University, University of Central Lancashire, University of Westminster, University of Lincoln and Napier University in Edinburgh at the present.

A 2004 Cochrane Collaboration review found that herbal therapies are supported by strong evidence but are not widely used in all clinical settings.^[63]

Types of herbal medicine systems

Dioscorides’ Materia Medica, c. 1334 copy in Arabic, describes medicinal features of cumin and dill.

Use of medicinal plants can be as informal as, for example, culinary use or consumption of an herbal tea or supplement, although the sale of some herbs considered dangerous is often restricted to the public. Sometimes such herbs are provided to professional herbalists by specialist companies. Many herbalists, both professional and amateur, often grow or "wildcraft" their own herbs.

Some researchers trained in both western and traditional Chinese medicine have attempted to deconstruct ancient medical texts in the light of modern science. One idea is that the yin-yang balance, at least with regard to herbs, corresponds to the pro-oxidant and anti-oxidant balance. This interpretation is supported by several investigations of the ORAC ratings of various yin and yang herbs.^[64][65]

In America, early settlers relied on plants imported from Europe, and also from local Indian knowledge. One particularly successful practitioner, Samuel Thomson developed a hugely popular system of medicine. This approach was subsequently broadened to include concepts introduced from modern physiology, a discipline called Physiomedicalism. Another group, the Eclectics, were a later offshoot from the orthodox medical profession, who were looking to avoid the then current medical treatments of mercury and bleeding, and introduced herbal medicine into their practices. Both groups were eventually overcome by the actions of the American Medical Association, which was formed for this purpose. Cherokee medicine tends to divide herbs into foods, medicines and toxins and to use seven plants in the treatment of disease, which is defined with both spiritual and physiological aspects, according to Cherokee herbalist David Winston.^[66]

In India, Ayurvedic medicine has quite complex formulas with 30 or more ingredients, including a sizable number of ingredients that have undergone "alchemical processing", chosen to balance "Vata", "Pitta" or "Kapha."^[67]

In Tamil Nadu, Tamils have their own medicinal system now popularly called the Siddha medicinal system. The Siddha system is entirely in the Tamil language. It contains roughly 300,000 verses covering diverse aspects of medicine such as anatomy, sex ("kokokam" is the sexual treatise of par excellence), herbal, mineral and metallic compositions to cure many diseases that are relevant even to-day. Ayurveda is in Sanskrit, but Sanskrit was not generally used as a mother tongue and hence its medines are mostly taken from Siddha and other local traditions.^[68]

In addition there are more modern theories of herbal combination like William LeSassier's triune formula which combined Pythagorean imagery with Chinese medicine ideas and resulted in 9 herb formulas which supplemented, drained or neutrally nourished the main organ systems affected and three associated systems. His system has been taught to thousands of influential American herbalists through his own apprenticeship programs during his lifetime, the William LeSassier Archive^[69] and the David Winston Center for Herbal Studies^[70]

Many traditional African remedies have performed well in initial laboratory tests to ensure they are not toxic and in tests on animals. Gawo, a herb used in traditional treatments, has been tested in rats by researchers from Nigeria's University of Jos and the National Institute for Pharmaceutical Research and Development. According to research in the African Journal of Biotechnology, Gawo passed tests for toxicity and reduced induced fevers, diarrhoea and inflammation ^[71]

Routes of administration

The exact composition of a herbal product is influenced by the method of extraction. A tisane will be rich in polar components because water is a polar solvent. Oil on the other hand is a non-polar solvent and it will absorb non-polar compounds. Alcohol lies somewhere in between. There are many forms in which herbs can be administered, these include:

• Tinctures - Alcoholic extracts of herbs such as Echinacea extract. Usually obtained by combining 100% pure ethanol (or a mixture of 100% ethanol with water) with the herb. A completed tincture has a ethanol percentage of at least 25% (sometimes up to 90%).^[72]. The term tincture is sometimes applied to preparations using other solvents than ethanol.
• Herbal wine and elixirs - These are alcoholic extract of herbs; usually with an ethanol percentage of 12-38% ^[72] Herbal wine is a maceration of herbs in wine, while an elixir is a maceration of herbs in spirits (e.g., vodka, grappa, etc.)
• Tisanes - Hot water extracts of herb, such as chamomile.
• Decoctions - Long-term boiled extract of usually roots or bark.
• Macerates - Cold infusion of plants with high mucilage-content as sage, thyme, etc. Plants are chopped and added to cold water. They are then left to stand for 7 to 12 hours (depending on herb used). For most macerates 10 hours is used.^[72]
• Vinegars - Prepared at the same way as tinctures, except using a solution of acetic acid as the solvent.
• Topicals:
  • Essential oils - Application of essential oil extracts, usually diluted in a carrier oil (many essential oils can burn the skin or are simply too high dose used straight – diluting in olive oil or another food grade oil such as almond oil can allow these to be used safely as a topical).^[73]
  • Salves, oils, balms, creams and lotions - Most topical applications are oil extractions of herbs. Taking a food grade oil and soaking herbs in it for anywhere from weeks to months allows certain phytochemicals to be extracted into the oil. This oil can then be made into salves, creams, lotions, or simply used as an oil for topical application. Any massage oils, antibacterial salves and wound healing compounds are made this way.
  • Poultices and compresses - One can also make a poultice or compress using whole herb (or the appropriate part of the plant) usually crushed or dried and re-hydrated with a small amount of water and then applied directly in a bandage, cloth or just as is.
• Whole herb consumption - This can occur in either dried form (herbal powder), or fresh juice, (fresh leaves and other plant parts).
• Syrups - Extracts of herbs made with syrup or honey. Sixty five parts of sugar are mixed with 35 parts of water and herb. The whole is then boiled and macerated for three weeks.^[72]
• Extracts - Include liquid extracts, dry extracts and nebulisates. Liquid extracts are liquids with a lower ethanol percentage than tinctures. They can (and are usually) made by vacuum distilling tinctures. Dry extracts are extracts of plant material which are evaporated into a dry mass. They can then be further refined to a capsule or tablet.^[72] A nebulisate is a dry extract created by freeze-drying.
• Inhalation as in aromatherapy can be used as a mood changing treatment^[74][75] to fight a sinus infection or cough ^[76], or to cleanse the skin on a deeper level (steam rather than direct inhalation here)

Examples of plants used as medicine

Few herbal remedies have conclusively demonstrated any positive effect on humans, possibly due to inadequate testing.^[77] Many of the studies cited refer to animal model investigations or in-vitro assays and therefore cannot provide more than weak supportive evidence.

• Aloe vera has traditionally been used for the healing of burns and wounds.^[78] A systematic review (from 1999) states that the efficacy of aloe vera in promoting wound healing is unclear, while a later review (from 2007) concludes that the cumulative evidence supports the use of aloe vera for the healing of first to second degree burns.^[78][79]
• Agaricus blazei mushrooms may prevent some types of cancer. ^[80]
• Artichoke (Cynara cardunculus) may reduce production cholesterol levels according to in vitro studies ^[81] and a small clinical study.^[82]
• Blackberry (Rubus fruticosus) leaf has drawn the attention of the cosmetology community because it interferes with the metalloproteinases that contribute to skin wrinkling.^[83]
• Black raspberry (Rubus occidentalis) may have a role in preventing oral cancer.^[84][85][86]
• Boophone (Boophone disticha) This highly toxic plant has been used in South African traditional medicine for treatment of mental illness ^[87]. Research demonstrate in vitro and in vivo effect against depression.^[88][89][90]
• Butterbur (Petasites hybridus)
• Calendula (Calendula officinalis) has been used traditionally for abdominal cramps and constipation.^[91] In animal research an aqueous-ethanol extract of Calendula officinalis flowers was shown to have both spasmolytic and spasmogenic effects, thus providing a scientific rationale for this traditional use.^[91] There is "limited evidence" that calendula cream or ointment is effective in treating radiation dermatitis.^[92][93]
• Cranberry (Vaccinium oxycoccos) may be effective in treating urinary tract infections in women with recurrent symptoms.^[94]
• Echinacea (Echinacea angustifolia, Echinacea pallida, Echinacea purpurea) extracts may limit the length and severity of rhinovirus colds; however, the appropriate dosage levels, which might be higher than is available over-the-counter, require further research.^[95][96]
• Elderberry (Sambucus nigra) may speed the recovery from type A and B influenza.^[97] However it is possibly risky in the case of avian influenza because the immunostimulatory effects may aggravate the cytokine cascade.^[98]
• Feverfew (Chrysanthemum parthenium) is sometimes used to treat migraine headaches.^[99] Although many reviews of Feverfew studies show no or unclear efficacy, a more recent RTC showed favorable results^{[100][101][102]} Feverfew is not recommended for pregnant women as it may be dangerous to the fetus.^[103][104]
• Gawo (Faidherbia albida), a traditional herbal medicine in West Africa, has shown promise in animal tests ^[105]
• Garlic (Allium sativum) may lower total cholesterol levels^[106]
• German Chamomile (Matricaria chamomilla) has demonstrated antispasmodic, anxiolytic, antiinflammatory and some antimutagenic and cholesterol-lowering effects in animal research.^[107] In vitro chamomile has demonstrated moderate antimicrobial and antioxidant properties and significant antiplatelet activity, as well as preliminary results against cancer.^[108][109] Essential oil of chamomile was shown to be a promising antiviral agent against herpes simplex virus type 2 (HSV-2) in vitro.^[110]
• Ginger (Zingiber officinale), administered in 250 mg capsules for four days, effectively decreased nausea and vomiting of pregnancy in a human clinical trial.^[111][112]
• Grapefruit (Naringenin) components may prevent obesity.
• Green tea (Camelia sinensis) components may inhibit growth of breast cancer cells^[113] and may heal scars faster.^[114]
• Purified extracts of the seeds of Hibiscus sabdariffa may have some antihypertensive, antifungal and antibacterial effect. Toxicity tested low except for an isolated case of damage to the testes of a rat after prolonged and excessive consumption.^[115]
• Honey may reduce cholesterol.^[116] May be useful in wound healing.^[117]
• Lemon grass (Cymbopogon citratus), administered daily as an aqueous extract of the fresh leaf, has lowered total cholesterol and fasting plasma glucose levels in rats, as well as increasing HDL cholesterol levels. Lemon grass administration had no effect on triglyceride levels.^[118]
• Magnolia
• Meadowsweet (Filipendula ulmaria, Spiraea ulmaria) can be used for a variety of anti-inflamatory and antimicrobial purposes due to presence of salicylic acid. Effective for fevers and inflammations, pain relief, ulcers and bacteriostatic. Listed as therapeutical in 1652 by Nicholas Culpeper. In 1838, salicylic acid was isolated from the plant. The word Aspirin is derived from spirin, based on Meadowsweet's synonym name Spiraea ulmaria. ^[119]
• Milk thistle (Silybum marianum) extracts have been recognized for many centuries as "liver tonics.".^[120] Research suggests that milk thistle extracts both prevent and repair damage to the liver from toxic chemicals and medications.^[121]
• Nigella sativa (Black cumin) has demonstrated analgesic properties in mice. The mechanism for this effect, however, is unclear. In vitro studies support antibacterial, antifungal, anticancer, anti-inflammatory and immune modulating effects.^{[122][123][124][125][126][127][128][129][130][131][132][133]} However few randomized double blind studies have been published.
• Ocimum gratissimum^[134][135] and tea tree oil can be used to treat acne.
• Oregano (Origanum vulgare) may be effective against multi-drug resistant bacteria.^[136]
• Pawpaw can be used as insecticide (killing lice, worms).^[137],^[138]
• Peppermint oil may have benefits for individuals with irritable bowel syndrome.^[139][140]
• Phytolacca or Pokeweed can be applied topically or taken internally. Topical treatments have been used for acne and other ailments. It is used as a treatment for tonsilitis, swollen glands and weight loss.
• Pomegranate contains the highest percentage of ellagitannins of any commonly consumed juice. Punicalagin, an ellagitannin unique to pomegranate, is the highest molecular weight polyphenol known.^[141] Ellagitannins are metabolized into urolithins by gut flora, and have been shown to inhibit cancer cell growth in mice.^[141][142]
• Rauvolfia Serpentina, high risk of toxicity if improperly used, used extensively in India for sleeplessness, anxiety, and high blood pressure.^[143]
• Rooibos (Aspalathus linearis) contains a number of phenolic compounds, including flavanols, flavones, flavanones, flavonols, and dihydrochalcones.^[144] Rooibos has traditionally been used for skin ailments, allergies, asthma and colic in infants.^[145] In an animal study with diabetic mice, aspalathin, a rooibos constituent improved glucose homeostasis by stimulating insulin secretion in pancreatic beta cells and glucose uptake in muscle tissue.^[146]
• Rose hips – Small scale studies indicate that hips from Rosa canina may provide benefits in the treatment of osteoarthritis.^{[147][148][149]} Rose hips show anti COX activity.^[150]
• Salvia lavandulaefolia may improve memory^[151]
• Saw Palmetto can be used for BPH. Supported in some studies,^[152] failed to confirm in others.^[153]
• Shiitake mushrooms (Lentinus edodes) are edible mushrooms that have been reported to have health benefits, including cancer-preventing properties.^[154] In laboratory research a shiitake extract has inhibited the growth of tumor cells through induction of apoptosis.^[154] Both a water extract and fresh juice of shiitake have demonstrated antimicrobial activity against pathogenic bacteria and fungi in vitro.^[155][156]
• Soy and other plants that contain phytoestrogens (plant molecules with estrogen activity) (black cohosh probably has serotonin activity) have some benefits for treatment of symptoms resulting from menopause.^[157]
• St. John's wort, has yielded positive results, proving more effective than a placebo for the treatment of mild to moderate depression in some clinical trials^[158] A subsequent, large, controlled trial, however, found St. John's wort to be no better than a placebo in treating depression^[159] However, more recent trials have shown positive results^{[160][161][162]} or positive trends that failed significance.^[163] A 2004 meta-analysis concluded that the positive results can be explained by publication bias^[164] but later analyses have been more favorable.^[165][166] The Cochrane Database cautions that the data on St. John's wort for depression are conflicting and ambiguous.^[167]
• Stinging nettle In some clinical studies effective for enign prostatic hyperplasia^[168] and the pain associated with osteoarthritis.^[169] In-vitro tests show antiinflammatory action.^[170] In a rodent model, stinging nettle reduced LDL cholesterol and total cholesterol.^[171] In another rodent study it reduced platelet aggregation.^[172]
• Valerian root can be used to treat insomnia. Clinical studies show mixed results and researchers note that many trials are of poor quality.^{[173][174][175]}
• Vanilla
• Willow bark (Salix alba) can be used for a variety of anti-inflamatory and antimicrobial purposes due to presence of salicylic acid and tannins. Has been in use for aprox. 6000yrs and was described in the 1st century AD by Dioscorides.^[176]

Safety

The safety and effectiveness of alternative medicines have not been scientifically proven^[4] and remain largely unknown.^[177]. A number of herbs are thought to be likely to cause adverse effects^[4] Furthermore, "adulteration, inappropriate formulation, or lack of understanding of plant and drug interactions have led to adverse reactions that are sometimes life threatening or lethal^[6]." Proper double-blind clinical trials are needed to determine the safety and efficacy of each plant before they can be recommended for medical use.^[178] Although many consumers believe that herbal medicines are safe because they are "natural", herbal medicines and synthetic drugs may interact, causing toxicity to the patient. Herbal remedies can also be dangerously contaminated, and herbal medicines without established efficacy, may be used to replace medicines that do have corroborated efficacy.^[77]

Standardization of purity and dosage is not mandated in the United States, but even products made to the same specification may differ as a result of biochemical variations within a species of plant.^[179] Plants have chemical defense mechanisms against predators that can have adverse or lethal effects on humans. Examples of highly toxic herbs include poison hemlock and nightshade.^[180] They are not marketed to the public as herbs, because the risks are well known, partly due to a long and colorful history in Europe, associated with "sorcery", "magic" and intrigue.^[181] Although not frequent, adverse reactions have been reported for herbs in widespread use.^[182] On occasion serious untoward outcomes have been linked to herb consumption. A case of major potassium depletion has been attributed to chronic licorice ingestion.^[183], and consequently professional herbalists avoid the use of licorice where they recognise that this may be a risk. Black cohosh has been implicated in a case of liver failure.^[184] Few studies are available on the safety of herbs for pregnant women^[185][186], and one study found that use of complementary and alternative medicines are associated with a 30% lower ongoing pregnancy and live birth rate during fertility treatment^[187]. Examples of herbal treatments with likely cause-effect relationships with adverse events include aconite, which is often a legally restricted herb, ayurvedic remedies, broom, chaparral, chinese herb mixtures, comfrey, herbs containing certain flavonoids, germander, guar gum, liquorice root, and pennyroyal^[188]. Examples of herbs where a high degree of confidence of a risk long term adverse effects can be asserted include ginseng, which is unpopular among herbalists for this reason, the endangered herb goldenseal, milk thistle, senna, against which herbalists generally advise and rarely use, aloe vera juice, buckthorn bark and berry, cascara sagrada bark, saw palmetto, valerian, kava, which is banned in the European Union, St. John's wort, Khat, Betel nut, the restricted herb Ephedra, and Guarana^[6].

There is also concern with respect to the numerous well-established interactions of herbs and drugs^[6]. In consultation with a physician, usage of herbal remedies should be clarified, as some herbal remedies have the potential to cause adverse drug interactions when used in combination with various prescription and over-the-counter pharmaceuticals, just as a patient should inform a herbalist of their consumption of orthodox prescription and other medication.

Dangerously low blood pressure may result from the combination of an herbal remedy that lowers blood pressure together with prescription medicine that has the same effect. Some herbs may amplify the effects of anticoagulants.^[189] Certain herbs as well as common fruit interfere with cytochrome P450, an enzyme critical to much drug metabolism.^[190]

Effectiveness

Running total of the number of research papers listed on PubMed from 1990-2007 containing the word "phytotherapy."

The gold standard for pharmaceutical testing is repeated, large-scale, randomized, double-blind tests. Some plant products or pharmaceutical drugs derived from them are incorporated into medicine. To recoup the considerable costs of testing to the regulatory standards, the substances are patented and marketed by pharmaceutical companies.^[191]

Many herbs have shown positive results in-vitro, animal model or small-scale clinical tests^[192] but many studies on herbal treatments have also found negative results.^[193] The quality of the trials on herbal remedies is highly variable and many trials of herbal treatments have been found to be of poor quality, with many trials lacking an intention to treat analysis or a comment on whether blinding was successful.^[194] The few randomized, double-blind tests that receive attention in medical publications are often questioned on methodological grounds or interpretation. Likewise, studies published in peer-reviewed medical journals such as Journal of the American Medical Association receive more consideration than those published in specialized herbal journals.

One study found that non-impact factor alternative medicine journals published more studies with positive results than negative results and that trials finding positive results were of lower quality than trials finding negative results. High impact factor mainstream medical journals, on the other hand, published equal numbers of trials with positive and negative results. In high impact journals, trials finding positive results were also found to have lower quality scores than trials finding negative results.^[193] Another study reported that some clinical studies of herbal medicines were not inferior to similar medical studies.^[195] However, this study used a matched pair design and excluded all herbal trials that were not controlled, did not use a placebo or did not use random or quasi random assignment.

Herbalists criticize mainstream studies on the grounds that they make insufficient use of historical usage, which has been shown useful in drug discovery and development in the past and present^[196]. They maintain that tradition can guide the selection of factors such as optimal dose, species, time of harvesting and target population.^[197]

Dosage is in general an outstanding issue for herbal treatments: while most medicines are heavily tested to determine the most effective and safest dosages (especially in relation to things like body weight, drug interactions, etc.), there are fewer varieties of dosages for various herbal treatments on the market. Furthermore, from a conventional pharmacological perspective, herbal medicines taken in whole form cannot generally guarantee a consistent dosage or drug quality, since certain samples may contain more or less of a given active ingredient.

Several methods of standardization may be applied to herbs. One is the ratio of raw materials to solvent. However different specimens of even the same plant species may vary in chemical content. For this reason, thin layer chromatography is sometimes used by growers to assess the content of their products before use. Another method is standardization on a signal chemical.^[198]

Clinical studies

In 2004 the U.S. National Center for Complementary and Alternative Medicine of the National Institutes of Health began funding clinical trials into the effectiveness of herbal medicine.^[199]

Name confusion

The common names of herbs (folk taxonomy) may not reflect differences in scientific taxonomy, and the same (or a very similar) common name might group together different plant species with different effects. For example, in 1993 in Belgium, medical doctors created a formula including some Traditional Chinese medicine (TCM) herbs for weight loss. One herb (Stephania tetrandra) was swapped for another (Aristolochia fangchi) whose name in Chinese was extremely similar but which contained higher levels of a renal toxin, aristolochic acid; this mistake resulted in 105 cases of kidney damage.^[200][201] Note that neither herb used in a TCM context would be used for weight loss or given for long periods of time. For this reason, Western herbalists use binomial nomenclature in their terminology within the profession.

In Chinese medicine these herbs are used for certain forms of acute arthritis and edema.^{[202][203][204]}

Standards and quality control

The issue of regulation is an area of continuing controversy in the EU and USA. At one end of the spectrum, some herbalists maintain that traditional remedies have a long history of use, and do not require the level of safety testing as xenobiotics or single ingredients in an artificially concentrated form. On the other hand, others are in favor of legally enforced quality standards, safety testing and prescription by a qualified practitioner. Some professional herbalist organizations have made statements calling for a category of regulation for herbal products.^[205] Yet others agree with the need for more quality testing but believe it can be managed through reputation without government intervention.^[206] The legal status of herbal ingredients varies by country.

In the EU, herbal medicines are now regulated under the European Directive on Traditional Herbal Medicinal Products.

In the United States, most herbal remedies are regulated as dietary supplements by the Food and Drug Administration. Manufacturers of products falling into this category are not required to prove the safety or efficacy of their product, though the FDA may withdraw a product from sale should it prove harmful.^[207][208]

The National Nutritional Foods Association, the industry's largest trade association, has run a program since 2002, examining the products and factory conditions of member companies, giving them the right to display the GMP (Good Manufacturing Practices) seal of approval on their products.^[66]

In the UK, herbal remedies that are bought over the counter are regulated as supplements, as in the US. However, herbal remedies prescribed and dispensed by a qualified "Medical Herbalist", after a personal consultation, are regulated as medicines.

A Medical Herbalist can prescribe some herbs which are not available over the counter, covered by Schedule III of the Medicines Act. Forthcoming changes to laws regulating herbal products in the UK, are intended to ensure the quality of herbal products used.

Some herbs, such as Cannabis, are outright banned in most countries. Since 2004, the sales of ephedra as an dietary supplement is prohibited in the United States by the Food and Drug Administration.^[209], and subject to Schedule III restrictions in the United Kingdom.

Danger of extinction

On January 18, 2008, the Botanic Gardens Conservation International (representing botanic gardens in 120 countries) stated that "400 medicinal plants are at risk of extinction, from over-collection and deforestation, threatening the discovery of future cures for disease." These included Yew trees (the bark is used for cancer drugs, paclitaxel); Hoodia (from Namibia, source of weight loss drugs); half of Magnolias (used as Chinese medicine for 5,000 years to fight cancer, dementia and heart disease); and Autumn crocus (for gout). The group also found that 5 billion people benefit from traditional plant-based medicine for health care^[210]. Some herbalists are aware of this problem and substitute least concern species as a result.

See also

References

Further reading

• Lindequist, U.; Niedermeyer, T.H.J. ; Jülich, W.D. (2005). "The pharmacological potential of mushrooms.". Evid Based Complement Alternat Med. 2: 285. doi:10.1093/ecam/neh107. PMID 16136207. http://ecam.oxfordjournals.org/cgi/content/full/2/3/285.  
• Lesley Braun and Marc Cohen. (2007). Herbs and Natural Supplements: An Evidence-Based Guide. Elsevier Australia. ISBN 072953796X 9780729537964.

External links

Associations

• National Herbalists Association of Australia, official website
• Irish Institute of Medical Herbalists, official website of the Irish Institute of Medical Herbalists, which is the professional organisation for herbalists in Ireland
• National Institute of Medical Herbalists, official website of the National Institute of Medical Herbalists, one of the governing bodies for herbalists in the United Kingdom
• College of Practitioners of Phytotherapy official website for College of Practitioners of Phytotherapy, one of the governing bodies for herbalists in the United Kingdom
• American Herbalists Guild- An Association of Herbal Practitioners, official website of the American Herbalists Guild

Herbalist

• The American Botanical Council Research and educational foundation.
• HerbMed Research and educational foundation.
• Medline All Herbs and Supplements.
• University of Maryland site about alternative medicine: uses, possible prescription drug interactions, and possible nutrient depletions
• The 55 Best Herbal Remedies
• Herbal treatments for common diseases

Criticism

• New England Journal of Medicine editorial about the risks of alternative medicine
• Herbal supplements not child's play - CNN news article
• Herbal Mythology - By Steven Novella MD, President of the New England Skeptical Society
• Selling Supplements - By Steven Novella MD, President of the New England Skeptical Society
• False Tenets of Paraherbalism
• Herbal Side Effects and Warnings
• Turning To Nature For New Drugs: How scientists are increasingly looking to nature for pharmacology clues

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