Botany, Nomenclature, Range

Kava is Piper methisticum Forst. from the pepper family, Piperaceae.

Depending on the area of the Pacific, Piper methisticum has been called Kava, awa, waka, lawena, or yaqona by the people who have used it perhaps for thousands of years.

It is a large-leaved swamp-loving plant, growing to six feet high, on average, and rarely up to 10 to 12 feet. It is probably indigenous to the South Sea Islands, somewhere west of Fiji, but because it has been cultivated for so many centuries, from New Guinea, Polynesia, to Micronesia, it is difficult to determine the exact original range. Up to 21 distinct varieties, each with slightly different effects, are noted by the indigenous people who have used it.

History of Use

Because of its importance as a ceremonial and beverage plant, kava is still cultivated in many parts of the Pacific. The plants are often tended in small gardens near houses.

Missionaries came to the islands and forbade the use of kava, partly because of the traditional way of chewing the root before consumption added saliva to the final concoction.

Constituents and Pharmacology

Various animal and human testing over the last 100 years or so has produced variable results. Some identified constituents showed stimulating activity, some sedative activity, and some no activity. In early testing, the original material used in the tests was not often identified precisely as to variety or even species, and where commercial herb samples were used, adulteration may have been a possibility.

Using modern analytical methods such as HPLC, it has become clear that there may be at least two major active fractions.

1. Lipid-soluble compounds:

A group of alpha-pyrones (6 major ones) with the 4-methoxy-2-pyrone ring system. The major compounds are kawain (34.5%), methysticin (20.8%), dihydrokawain (17.1%), dihydromethysticin (5.3%), and yangonin (0.8%). The percentages are based on the ethyl acetate extract (Smith, et al.). The total pyrone content of the rhizome is usually about 3-4% (Lewis & Lewis).

2. Water-soluble compounds:

A polar molecule of molecular weight 1000-10,000, showing a sedative effect in animal tests, has not yet been characterized.

Pharmacological effects such as cerebral depression, a heartbeat-steadying effect (Lewis & Lewis), and an anxiolytic (Singh, 1981) effect have been noted, and a number of animal tests have been performed--for a review of these see Keller & Klohs (1963).

Identification

Adulteration of kava powder has been reported, and because constituent levels and overall activity of kava have been reported to vary according to the variety, growing, harvesting, drying, and processing methods (Duve, 1981), testing with HPLC or at least TLC is a good way to insure quality material is used for bulk herb or various products in trade. A method of HPLC identification of the major active lipid-soluble constituents identified thus far can be found in Smith, et al. (1984).

Uses

Kava prepared from the fresh roots and rhizome is said to have stronger narcotic effects than that prepared from the dried material. Some authors emphasize that kava prepared by the Tongan (chewing, mixing with saliva) is stronger than when the rhizomes are simply crushed by means other than chewing and macerated in cool water, then strained. Fresh kava that is prepared by boiling is said to have a stronger and quicker effect than when prepared by cool maceration. I have noticed only mild relaxing effects from consuming two cups of hot kava tea prepared from the commercially-available cut and sifted rhizome, but commercial dry forms of kava have been said to be adulterated, and quality differs widely, depending on the variety and probably the length of time the root has been stored.

There are a number of variations on the reported psychotropic effects of consuming kava. One early observer (Hocart) said "As I experienced it, it gives a pleasant, warm, and cheerful, but lazy feeling, sociable though not hilarious or loquacious; the reason is not obscured (Gatty)."

Kava drinking is often associated with the "noble class" or royalty, but several authors report that the noble class drank socially and for pleasure, the priest class used it ceremoniously, and the working class for relaxation.

Kava was very much used as a medicine, and some varieties were considered better for this purpose than others.

Priests often used kava for divination, and the drink was "offered to such supernaturals as the shark patron." "Psychic diagnosticians" drank kava to increase the power of the spirits, and in Samoa it was used to "bring forth inspiration."

Bingh (1983) has summarized the uses of kava in the islands of Oceania:

"It is used in ceremonies to welcome distinguished visitors, at formal gatherings of initiation or completion of work, validation of titles, celebration of marriages, births or deaths, as a libation to the gods, to cure illnesses and to remove curses, in fact in almost all phases of life in the islands."

Kava is variously used in different cultures to relieve fatigue, possibly by relaxing and helping to provide a deep sleep. As mentioned, kava was widely used for its medicinal effects. It was often valued as a diuretic, and energy-promoting herb, as a cure for rheumatism, asthma, worms, obesity, as a poultice for headaches, and as a diaphoretic, to induce sweating during colds or fevers (Gatty). It was very popular for various skin diseases, such as fungal infections and even leprosy. Finally, it was considered safe enough to give to children who were weak and recovering from illnesses.

Kava enjoyed a short-lived popularity in Germany about 1896, when patent remedies were sold as urinary tract antiseptics and diuretics.

Toxicology and Regulatory Status

Moderate use does not appear to be particularly harmful, and it should be remembered that kava has been an important social, ritual, and health drink in several Pacific Island cultures for centuries. This use is extremely well documented by casual observers and scientists (anthropologists, sociologists) alike. Because of its long use in almost every aspect of daily life, there is a good case to be made for defining kava as GRAS (generally recognized as safe).

As is often the case with foods, beverages, and natural medicines, over-use or habitual use of kava can lead to such side-effects as indolence, weakness, leg paralysis, and a peculiar scaly skin rash, which are said to be completely reversible when kava consumption is discontinued--as long as the consumption has not been very high over a prolonged period.

References
Anonymous. "Kava." The Lancet, July 30, 1988.

Singh, Y.N. 1983. "Effects of kava on neuromuscular transmission and muscle contractility." xx of Pharmacology 7: 267-76.

Duve, R.N. 1981. "Gas - liquid chromatographic determination of major constituents of Piper methysticum." Analyst 106: 160-5.

Duve, R.N. & F. Prasad. 1981. "Quality evaluation of yaqona (Piper methysticum) in Fiji. Jiji Agricultural Journal 43: 1-8.

Gatty, R. "Kava--Polynesian Beverage Shrub." Economic Botany xx: 241-49.

Gregory, R.J., et al. 1977. "The relationship of kava to a cultural revitalization movement. Report to the U.S. Public Health Service, National Institute of Drug Abuse.

Keller, F. & M.W. Klohs. 1963. "A Review of the Chemistry and Pharmacology of the Constituents of Piper methysticum." Lloydia 26: 1-15.

Singh, Y.N. 1981. "A review of the historical, sociological and scientific aspects of kava and its uses in the South Pacific." Fiji Medical Journal, April/May.

Sitaleki, A., et al.

Smith, R.M., et al. 1984. "High-performance liquid chromatography of kava lactones from Piper methysticum." Journal of Chromatography 233: 303-8.