Piperaceae
Piper methysticum
Kava · Kava kava · Awa · Yaqona
- Part used
- rootrhizome
- Native range
- Western Pacific — Vanuatu, Fiji, Samoa, Tonga, Hawaii; a cultigen, not known wild
- Morphology
- A shrub to three metres with heart-shaped leaves and jointed stems. Sterile: it does not set seed and is propagated entirely from cuttings, so every plant is a clone of a line selected by people.
What is in it
Evidence
Meta-analyses of aqueous and standardised kava extracts show a real anxiolytic effect against placebo in generalised anxiety, and it is one of the better-supported herbal preparations. Its safety history is what has kept it out of routine use.
Safety
Associated with severe hepatotoxicity, including cases requiring transplant and some deaths, which led to bans across Europe from 2002. The picture is genuinely contested and the detail matters: the traditional Pacific preparation is an aqueous extract of the peeled root and has a far better safety record than the acetone and ethanol extracts implicated in most European cases, some of which used aerial parts that Pacific practice does not use. Several national bans were later relaxed or overturned. Heavy chronic use produces a characteristic scaly dermopathy.
Interactions: Additive sedation with alcohol, benzodiazepines and other CNS depressants; Additive liver risk with hepatotoxic drugs
Regulatory: In Australia, kava is permitted for personal importation within limits and is regulated as a food in aqueous root preparations. Restrictions vary widely by country.
Historical use
The central social and ceremonial drink of much of the western Pacific, prepared as a cold water infusion of the root and drunk communally. Attested for at least three thousand years, and bound up with formal hospitality, dispute settlement and rank.
Recorded as history and attributed where possible. Long use establishes that a plant was widely used, not that it worked, and not that it was safe.
Worth knowing
Kava is the clearest case in this collection of the solvent deciding the outcome.
Two thousand years of Pacific use with no signal of liver failure; a decade of European acetone-extracted capsules with a cluster of them. The obvious reading is that a stronger solvent pulled out something that water leaves in the plant — probably including the flavokavains, and possibly compounds concentrated in the stem peelings and leaves that traditional preparation discards.
Its taxonomy is genuinely unsettled, which is unusual for a plant this important. Kava is sterile — it sets no seed and every plant alive is a cutting from a line people selected — and several treatments regard it not as a species in its own right but as a cultivar group derived from Piper wichmannii. The GBIF backbone has no species-level record for it at all, which is why this entry is not stamped as nomenclature-verified.
It is also a case where a regulatory response fell hardest on the countries that had used the plant safely for millennia. The European bans collapsed the Pacific kava export trade, and the question of who bears the cost of a precaution taken elsewhere is a real one.
Nomenclature not yet verified against an external authority.