A particular form of the herbal remedy kava may safely ease anxiety symptoms in some people, a small study suggests.
Kava, a member of the pepper family, is native to the islands of the South Pacific, where the dried roots of the plant have long been used to make a traditional beverage. In the West, kava extracts have been promoted as a way to reduce anxiety, promote sleep and relax the muscles.
However, reports of liver damage linked to kava supplements led the UK, Europe and Canada to ban the herb in 2002. In the U.S., the Food and Drug Administration warned consumers to be cautious about using kava-containing products.
For the new study, published in the journal Psychopharmacology, Australian researchers tested the effects of a particular water-soluble kava extract currently sold in that country.
Research suggests that the liver risk linked to kava supplements may be related to some products' formulation; many supplements are alcohol-based extracts that contain plant parts not used in traditional kava preparations.
The water-soluble, or "aqueous," extract used in the current study was derived from the peeled rootstock of a medicinal cultivar of kava, and may therefore be safer, lead researcher Jerome Sarris, a doctoral candidate at the University of Queensland, told Reuters Health.
To test the product, Sarris and his colleagues had 60 adults with chronic anxiety symptoms take either the kava pills or placebo pills for one week. During the second treatment week, placebo patients were switched to kava and kava patients to placebo.
Warwick, Australia-based MediHerb Pty Ltd supplied the kava extract.
In general, the study found, patients' anxiety symptoms declined on the kava extract, as did depression symptoms in some. There were no signs of liver toxicity or other serious side effects, according to the researchers.
More studies should now investigate water-soluble kava supplements for treating anxiety disorders, according to Sarris.
"There is to my knowledge no documented evidence of liver toxicity using the traditional kava method — correct cultivar, peeled rootstock and using a water extraction method," he noted.
For now, Sarris said, consumers who want to try the herbal remedy could consider getting a liver function test first, and use the product under the supervision of a health professional. It is also best, he added, not to mix kava with alcohol or any other medications.