Kava: From Ethnology to Ethnopharmacology by Yadhu N. Singh. Boca Raton, FL: CRC Press; 2004. 167 pp. $99.95. ISBN 0-415-32327-4.

This book is part of the “Medicinal and Aromatic Plants: Industrial Profiles” series of 40 titles from CRC. It contains the same organization found in the entire series: Introduction; history, folklore, traditional and current use; production, marketing, and quality assurance; botany and ethnobotany and current use; chemistry of kava and kavalactones; pharmacology and toxicology of kava and its kavalactones; and clinical studies and therapeutic implications.

Written by a Fijian pharmacologist with a strong expertise on kava, this book is an authoritative treatment on this fascinating herb. The author has previously published numerous papers on the botany, ethnobotany and ritual use, and pharmacology of kava and is the senior author of an extensive review published in HerbalGram in 1997.¹

Kava (Piper methysticum Forst., Piperacea) is the most esteemed botanical in the native cultures of the South Pacific. The traditional herb became a popular phytomedicine and dietary supplement in the United States, Western Europe, Australia, and other areas. After meteoric growth in the 1990s, sales of kava (also called kava kava) have dropped precipitously as a result of negative publicity and regulatory actions responding to numerous cases of hepatotoxicity that have been allegedly associated with its use. The German government (usually a leader in recognizing the value and relative safety of many herbs and phytomedicinals, including kava) unexpectedly banned kava as a medicine in 2002, despite strong suggestions to the contrary by the esteemed Commission E, and at least seven other countries that rapidly followed suit.

The bans have occurred despite the lack of compelling mechanistic pharmacological evidence supporting a hepatotoxicity mechanism, as has been reported in several articles in this journal.^2,3 Further, critical reviews of kava case reports by various experts fail to establish conclusive evidence of a causal relationship between kava consumption and liver toxicity. Most of these kava-associated cases of hepatotoxicity contain other confounding variables (pre-existing liver disease, use of hepatotoxic drugs, moderate to heavy use of alcohol) that make a direct causal link impossible to document. However, here in the United States product liability insurance rates for kava herbal products have risen sharply, forcing many companies to discontinue kava sales, a business decision based on increased costs, not based on any general consensus of alleged risks.

While the interest in kava from an ethnobotanical and ritualistic perspective formerly dominated much of the coverage about kava, the issue of potential hepatotoxicity has taken center stage for obvious reasons. The author deals with this by citing the various reports that have been compiled as late as 2002 (the apparent time when the volume was completed) as well as discussing the speculative evidence about kava and possible drug interactions. After reviewing clinical trials on kava’s benefits, he concludes that it is a “relatively safe and effective herbal agent for treating everyday anxiety and probably for full-blown anxiety disorders as well.”

Kava’s efficacy in treating the symptoms of anxiety is well established. A meta-analysis of seven controlled clinical trials on a proprietary standardized kava extract from Germany has demonstrated the extract’s safety and efficacy as an anxiolytic. Additional trials on other formulations have similar conclusions. This is hardly surprising to anyone who has attended a kava ceremony in the South Pacific or Hawaii, or has otherwise ingested the bitter-tasting beverage or extract made of kava root and rhizome. A kava beverage, drug, or dietary supplement made from kava root will have an almost immediate effect on a person; within 10 to 20 minutes one will feel the mild relaxing effects on skeletal muscles, while mental faculties remain clear.

It is unclear whether kava will regain its former short-lived popularity as a licensed drug in Western European countries and elsewhere, and as a dietary supplement in the U.S. As reported in HerbalGram recently,⁴ an international group is attempting to influence various governments to reconsider their previous bans (the UK’s Medicines Control Agency has already agreed to do so in 2005) and the World Health Organization (WHO) is reportedly reconsidering its position on kava. The WHO’s position is based mainly on the recognition that there is a lack of adequate scientific evidence demonstrating a direct causal link between kava ingestion and the reported cases of hepatotoxicity.

Consequently, access to authoritative scientific and medical information on kava will be needed by many groups in their attempts to evaluate the safety of this controversial traditional herb. This book will help all those who are engaged in such safety evaluations.

—Mark Blumenthal

References

1. Singh YN, Blumenthal M. Kava: An Overview. Distribution, mythology, botany, culture, chemistry, and pharmacology of the South Pacific’s most revered herb. HerbalGram. 1997;No. 39:33-55.

2. Blumenthal M. Kava safety questioned due to case reports of liver toxicity: Expert analyses of case reports say insufficient evidence to make causal connection. HerbalGram. 2002;No. 55:26-32.

3. Tavana G, Stewart P, Snyder S, et al. Lack of evidence of kava-related hepatotoxicity in native populations in Savaii, Samoa according to a survey of traditional healers and biomedical practitioners. HerbalGram. 2003;No. 59:28-32.

4. Gruenwald J. Kava Stakeholders Plan Regulatory Review and Market Return. HerbalGram. 2004;No. 61:69-70.