Scientists at the University of Hawaii have found evidence that kava leaves and stems—parts of the plant not traditionally used—may be to blame for the liver damage that led to kava being banned in countries from Germany to Australia.
CS Tang, professor of Environmental Biochemistry at the University of Hawaii, said that kava's liver toxicity is not a result of kavalactones, the active ingredient found in the plant's root, but of an alkaloid known as pipermethystine.
"This compound is not found in the roots," Tang said, "but only in the green—the peelings and leaves."
His team found evidence that supplements manufacturers commonly purchased leaves and stems during the height of the kava boom.
Michael McIntyre, chairman of the European Herbal Practitioners Association, said regardless of whether or not the suspect products contained stems and peelings, the initial German studies that sparked the controversy were clearly flawed.
"Some of the cases are presented as different ones when they are in fact the same case," he said.
In the UK, the National Association of Health Stores has commenced legal action against the Medicines and Healthcare Products Regulatory Agency (formerly the Medicines Control Agency) and the Food Standards Agency, claiming there is not enough evidence to justify the ban imposed in January.