Captain James Cook, whilst exploring remote Pacific islands on his second voyage (1772-1775), noted in his ship's log that members of his crew experienced symptoms similar to opium when consuming a drink local peoples called kava. A member of his crew, Georg Forster, provided the first detailed description of the plant from which this drink was made and in 1786 described it as Piper methysticum; 'intoxicating pepper'.
Piper methysticum is indigenous to Polynesia, Micronesia and Melanesia where it has been used for more than 2,000 years. It has many local names but the most common in the South Pacific is kava, which refers to both the beverage and the plant. Once only used in traditional ceremonies it became a popular recreational drink that gives mild psychoactive effects. These effects include intoxication, muscle relaxation and eventually sleepiness. Kava has been used for other traditional uses include as a sedative and for the treatment of conditions such as anxiety.
Cultivated kava is thought to have been originally selected from a wild subspecies with powerful pharmacological effects that is used only by traditional Pacific herbalists. Today, there are more than 200 cultivated kava varieties, all of which are sterile and must be propagated by cuttings. Kava varieties are group into noble sorts and two-day sorts. Traditionally, noble varieties of kava are used, whilst two-day varieties have high kavalactone contents and are named because of their lasting psychotropic effects. Kava root contains six major kavalactones, whilst the stem, and root skin, contains numerous alkaloids. Consequently, the composition of the beverage is highly variable depending on the variety and parts of the plant used.
The beverage is traditionally prepared by peeling the fresh or dried root, pounding it to a pulp or powder and mixing with water or coconut milk; parts of the stem and peelings may also be added. Whilst moderate consumption apparently has no adverse health effects, high levels of use can cause skin rashes, weight loss, nausea, loss of appetite and indigestion; symptoms which are reversible when kava use is stopped.
As a recreational drug, kava use spread beyond the Pacific islands to Africa and northern Australia, and by the 1990s kava extracts were being marketed in many parts of the world as dietary supplements and for anxiety disorders. However, cases of hepatoxicity led to kava being withdrawn from some countries, including most of those in Europe, in the early twenty-first century.
FAO and WHO 2016. Kava: a review of the safety of traditional and recreational beverage consumption. FAO and WHO.
Lebot V and Levesque J 1996. Evidence for conspecificity of Piper methysticum Forst.f. and Piper wichmannii C.DC. Biochemical Systematics and Ecology 24: 775-782.
Lebot V et al. 1992. Kava-the Pacific elixir: the definitive guide to its ethnobotany, history, and chemistry. Yale University Press.