Kava's Link to Liver Disease Questionable

An analysis by American toxicologist/pharmacologist Prof. Donald Waller, of the College of Pharmacy at the University of Illinois at Chicago, of the approximately 30 hepatic adverse event reports (AERs) from Germany and 5 submitted to the FDA between May 1998 and September 2001 concluded that there is "no clear evidence that the liver damage reported in the U.S. and Europe was caused by the consumption of kava," and that those cases in which there is a possible association between the use of a kava extract and liver dysfunction "appear to have been hypersensitivity (allergic) or idiosyncratic responses" (1). He also stated that in many of the cases, the development of liver problems could be explained by the concomitant use of alcohol or drugs that have the potential to damage the liver. However, Dr. Waller acknowledged that he did not have adequate medical information on all the case reports to adequately assess them.

     Two American case reports suggest relative safety of kava. In one case in which four prescription drugs, plus relatively high levels of kava were used (300 pills, equivalent to 45,000 mg kava per day!), there was no liver damage observed; in another case a 13-year-old girl consumed eight to ten 500 mg tablets in a suicide attempt, but recovered the following morning. "From a toxicologist perspective, these two cases provide some evidence that kava itself is not a direct hepatotoxin even in extremely high concentrations" (1).

Kava Safety and Precautions
     The kava-liver safety issue comes as somewhat of a surprise to most industry members, health professionals and consumers familiar with the history and clinical use of kava. There is little evidence in the scientific literature to suggest liver toxicity; and the herb has enjoyed safe use for centuries in the South Pacific. Recently, a Duke University clinical trial to assess the adverse effects profile of an American kava extract found only insignificant elevations of liver enzymes in 3 of the 38 subjects in the trial (one with elevated levels initially), concluding that kava is relatively safe (2).

     Because of the confusion and the potential seriousness of the issue, on December 20, 2001, the American Botanical Council issued the following cautions:

Kava should not be used by anyone who has any liver problems, or by anyone who is taking any drugs with known adverse effects on the liver or anyone who is a regular consumer of alcohol.
Since the reports so far are associated with chronic use, kava should not be taken on a daily basis for more than four weeks (without the advice of a qualified professional).
In addition, consumers should discontinue use if symptoms of jaundice (i.e. dark urine, yellowing of the eyes) occur.
Consumers should consult their primary healthcare provider if they have a history of liver problems or suspect possible liver problems before using kava or continuing its use (3).

References

Waller DP. Report on Kava and Liver Damage. Silver Spring, MD: American Herbal Products Association. 2002
Connor KM et al. Adverse-effect profile of kava. CNS Spectrums 2001;6(10):848-53.
American Botanical Council. American Botanical Council Announces New Safety Information on Kava [press release]. Austin, TX, 2001 Dec 20.