kava kava
Meaning of kava kava: A Pacific island drink turned capsule, calming enough to show up in trials and tied to rare but severe liver injury.
Definition of kava kava
Kava kava is a shrub of the pepper family, Piper methysticum, grown across the Pacific islands, where a drink prepared from its pounded root has long been central to social and ceremonial life. The root contains kavalactones, fat-soluble compounds that relax muscles and ease tension. Extracts standardized for those compounds are sold as supplements, marketed mainly for anxiety and poor sleep.
What is in the root?
Around half a dozen kavalactones account for most of the effect, and the mix of them differs between cultivars, which is why one preparation can feel quite unlike another. They do not act on a single target. Effects on the brain's main calming signal, on the channels that carry nerve impulses, and on muscle tone have all been described, and the full picture is not settled. The species name methysticum comes from the Greek for intoxicating, although the state produced is not drunkenness: thought stays clear while the body loosens, which is precisely why the drink occupies the social role it does.
Does it work for anxiety?
Better than most herbal preparations manage. Pooled trials of standardized extract have found a modest reduction in anxiety scores against placebo, which places it among the few plant remedies with reasonably consistent supporting evidence. The effect measured is small and the studies are mostly short, so it does not stand comparison with prescribed treatment. Heavy long-term use produces a distinctive dry, scaly, flaking rash that clears once use stops, and unsteadiness on the feet is common at higher intake.
Why did regulators become concerned?
| Aspect | Traditional preparation | Commercial extract |
|---|---|---|
| Plant part | Peeled root and rootstock only | Often stem peel and leaf as well |
| Solvent | Cold water | Water, ethanol or acetone, varying by product |
| Pattern of use | Shared socially, in bouts | Capsules taken daily for months |
Reports of severe liver injury, a few of them ending in liver failure, prompted the Food and Drug Administration to issue a consumer advisory and several European regulators to suspend sales. The cases were rare against the amount consumed worldwide and appeared unpredictable rather than dose-related. Attention has focused on the differences set out above, since the parts of the plant discarded in traditional practice carry compounds the water-based drink does not. Kavalactones also occupy the liver enzymes that process many medicines, and sedation adds to that of alcohol and of sleeping and antianxiety drugs.
Also known as
Used in a sentence
The patient reported daily use of a kava kava supplement for sleep.
Good to know
Reports of severe liver injury have been rare relative to how widely kava is consumed and have drawn attention to products made with organic solvents or with stem and leaf material, which traditional water preparation of the peeled root does not use.