The South Pacific herb, Kava Kava, is a best-seller — ranking ninth in
retail U.S. sales in mainstream markets in 2000 — based on its proven
ability to relieve stress, anxiety and tension. Recently kava has come
under the scrutiny of the United States Food and Drug Administration
(FDA), which is acting on reports from Europe that kava may damage the
liver. The agency noted that German and Swiss health authorities have
identified approximately 30 cases of sometimes-serious liver toxicity,
including four cases requiring transplantation, and one death, that are
believed to be associated with kava consumption. Based on these reports,
the U.K. has banned sales of kava products and German authorities have
notified manufacturers of kava products that their licenses to market
the herb could be withdrawn.
The Evidence So Far
Closer examination of the scant details available on the 30 European
cases reveals that the vast majority, 21 cases in all, involved the
concomitant use of hepatotoxic drugs and/or alcohol. This is not
significant evidence of hepatotoxicity.
Jerry Cott, PhD., former Chief of the Psychopharmacology Research
Program at the National Institute of Mental Health said, "If the
incidence of liver toxicity for kava is correct, then according to
German researchers it is very similar to that of conventional
pharmaceutical anti-anxiety and antidepressant prescription drugs. These
are generally considered to be acceptable (though small) risks," he
said, referring to the risk-benefit comparison by which conventional
medicines are evaluated. Cott also pointed out that a small clinical
study from Duke University published in October showed no adverse
effects from kava on the liver.
The fact is, you are far likelier to suffer from liver damage by taking
the prescription anti-anxiety drug, Valium, as you are kava, yet it is
taken by millions daily with little question-and with no major adverse
publicity. The over-the counter pain medication, acetominphen (Tylenol),
also has a high incidence of liver toxicity, especially when combined
with alcohol.
The Research
Kava has a long traditional use in the South Pacific at often
considerably higher doses than those used in Europe i with few reported
liver toxic effects, and its safety/toxicity has been studied
extensively in recent years. In 1990 the German government's Commission
E, a panel of herbal experts in the fields of medicine and pharmacy,
evaluated the scientific and medical literature and had approved the use
of kava as a nonprescription medicine for "nervous anxiety, stress, and
restlessness."
The longest running study conducted to date, with 101 people for 6
months taking 70mg 3/day had negligible side effects, and in fact, more
of the placebo subjects reported side effects than those taking kava.
The researcher concluded that, "in contrast to both benzodiazapines and
antidepressants, kava possesses an excellent side-effect profile." ii
The safe and effective benefits of kava to relieve symptoms of anxiety
were also supported in a meta-analysis, a systematic statistical review
of seven human clinical trials published in 2000 in the Journal of
Clinical Psychopharmacology, and again in a similar critical review in
2001. The reviews did not find significant adverse effects related to
liver toxicity.