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Toxicologist's Review of Kava Cases
29 March 2002
by Wyn Snow, Managing Editor

In response to concerns raised by recent cases of liver toxicity in people who were taking supplements containing kava (Piper methysticum), a group of supplement trade associations hired toxicologist Donald Waller to examine the evidence.

Dr. Waller found that the existing evidence does not indicate that kava use caused the liver disease. However, the available medical information lacks important details, and Dr. Waller recommended that additional information be provided in order to be entirely conclusive.

Preliminary evidence appears to indicate idiosyncratic responses

Dr. Waller reported to the US Food and Drug Administration (FDA) on 19 February 2002 that "there is no clear evidence that the liver damage reported in the US and Europe was caused by the consumption of kava." Cases with a possible association between kava intake and liver problems "appear to have been hypersensitivity or idiosyncratic base responses."

Dr. Waller also pointed out two cases of consumption of very large quantities of kava which "provide some evidence that kava itself is not a direct hepatotoxin even in extremely high concentrations."

Don't mix kava with known liver problems

Dr. Waller recommended that both physicians and consumers be made aware that people should avoid kava if they:

  • use prescription drugs associated with liver damage
  • drink large amounts of alcohol
  • have pre-existing liver disease or compromised liver function

The supplement groups and toxicologist

The group that hired Dr. Waller consists of the American Herbal Products Association (AHPA), the Council for Responsible Nutrition (CRN), the National Nutritional Foods Association (NNFA) and the Utah Natural Products Alliance (UNPA).

Donald P. Waller, PhD, is a Professor of Pharmacology and Toxicology in the Department of Pharmaceutics and Pharmacodynamics at the University of Illinois at Chicago's College of Pharmacy, and is also a Diplomate of the American Board of Toxicologists.


American Herbal Products Association, private communication, 26 March 2002.end-of-story




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