Kratom (Mitragyna speciosa) is a medicinal leaf harvested from a large tree native to Southeast Asia in the Rubiaceae family, first documented by Dutch colonial botanist Korthals. It is botanically related to the Corynanthe, Cinchona and Uncaria genera and shares some similar biochemistry. It is in the same family as coffee and the psychoactive plant Psychotria viridis. Other species in the Mitragyna genus are used medicinally in Africa, and also used for their wood.
Kratom is used for its psychoactive effects in its native region, with growing use elsewhere in the world. It is grown widely in Indonesia for worldwide trade. In Southeast Asia the fresh leaves are usually chewed, often continuously, by workers or manual laborers seeking a numbing, stimulating effect. Less commonly, the leaves are decocted or extracted into water and then evaporated into a tar that can be swallowed. Kratom is not often smoked, although this method does provide some effect.
Kratom contains many alkaloids including mitragynine (once thought to be the primary active), mitraphylline, and 7-hydroxymitragynine (which is currently the most likely candidate for the primary active chemical in the plant). Although 7-hydroxymitraygynie and mitragynine are structurally related to yohimbine and other tryptamines, their pharmacology is quite different, acting primarily as mu-opioid receptor agonists. Kratom also contains alkaloids found in uña de gato, which are thought to play a beneficial role on the immune system and lower blood pressure, as well as epicatechin, a powerful antioxidant also found in dark chocolate and closely related to the EGCG that gives green tea its beneficial effects. Other active chemicals in kratom include raubasine (best known from Rauwolfia serpentina) and some yohimbe alkaloids such as corynantheidine.
Kratom's pharmacology shares some elements of the activity of other substances including yohimbine. Kratom also has a yohimbe-like stimulant activity, and uncaria-like immunostimulant activity. Kratom is said to produce a sense of well-being, with users reporting anti-depressant, anti-anxiety, analgesic, and even euphorigenic effects. It is paradoxically a stimulant and depressant, used to aid work and also able to contribute to rest and sleep. Kratom's psychoactive effects are reported to be relatively short-lived, typically fading after a few hours. Some people experience nausea and even vomiting after ingesting kratom, and though this may be a result of its extremely bitter taste, no definitive research has been done to test this hypothesis. Another possible effect is constipation. Kratom is mildly addictive and withdrawal is possible after frequent heavy use. While rarely severe or disabling, withdrawal symptoms can include depression, fatigue, restlessness, teary eyes, and insomnia. It is comparable to morphine withdrawal in character and caffeine withdrawal in severity.
The most potent leaves generally come from older trees, most of which grow on mildly acidic jungle type soils. The large leaves are most revered. Different strains, with names such as 'Rifat' and 'Bumblebee' are now being selected and vegetatively cloned for their allegedly higher innate alkaloid content. However, genetics are only a small variable with mitragyna speciosa. Alkaloid content is a function of age, genetics, soil, location, and season. Alkaloid production is highest in late summer and early fall. There are some reports that kratom grown in sub-tropical or mild tropical conditions may not be active, or will be less potent than kratom growing in the deep tropics. Again, reports vary sharply in this regard. Some make this claim, while others claim to have grown perfectly potent plants under such conditions.
Kratom is a potentially large tree, though it usually grows to a height of 12–15 ft tall and 15 ft (4.6 m) wide. Depending on the species, soil and climate, it can grow up to 40–100 feet tall.
The leaves of the Kratom tree are a dark green colour and can grow over 7 inches (180 mm) long and 4 inches (100 mm) wide. The flowers are yellow and grow in clusters.
The kratom tree likes it best to be in wet, humid, fertile soil, to have medium to full sun exposure, and an area protected from strong winds. Light winds are beneficial to the production of active alkaloids.
Kratom can be grown for personal use, and there are several sites selling plant clones. They do not like cold conditions and frost will result in loss of all leaves. If you live in climate zone 10, kratom can be grown outside year round. If you're outside of this zone, plants need to be kept indoors during cold spells. Kratom plants prefer a humid environment and should be fertilized every few weeks (during growth periods).
Kratom is a controlled substance in Thailand, Bhutan, Australia, Finland, Denmark, Poland, Lithuania, Malaysia and Myanmar (Burma). A handful of people in Malaysia and possibly other countries are lobbying their governments to allow medical research into kratom as a potential prescription substance.
The United States Drug Enforcement Administration has added Kratom to their list of drugs and chemicals of concern.
K. S. Grewal, The Effect of Mitragynine on Man, British Journal of Medical Psychology 1932, 12: 41-58