Austin, TX. (December 20, 2001). Herbal experts are advising caution with the use of the popular herb kava.
The American Botanical Council (ABC) is suggesting that consumers follow additional precautions when using kava, an herb used for reducing symptoms of anxiety and stress.
Recent case reports from Europe suggest a possible association of some kava products and liver problems. Regulatory officials in Germany have expressed concerns over cases of liver problems associated with kava and have notified kava manufacturers that licenses to market the herb could be withdrawn by the government, pending review of information submitted by the German kava industry.
On November 8 the German government provided an explanation for its proposal: In the past several years, there have been 24 adverse event reports (AERs) of hepatotoxicity reportedly associated with oral use of kava preparations in Germany and five in Switzerland.
In 18 cases conventional prescription or over-the-counter pharmaceutical drugs with known or potential liver toxicity were also being used, but the exact nature of the problem is not clear.
“No reports of adverse liver effects of kava have been published in the U.S.,” said Mark Blumenthal, founder and executive director of ABC, a nonprofit herbal research and education organization. He noted that the U.S. Food and Drug Administration has now indicated that there are a small number of adverse events in its unpublished database. This was first reported in the FDA’s letter to healthcare professionals on December 18.
“Despite the relatively good safety profile that kava has in the U.S., we need to take this action by the German government very seriously,” Blumenthal added. “Germany has led the world in clinical research and rational regulation of herbal medicines. If their regulators think there’s a problem, then we need to look at this situation very carefully. It is unclear what specific action Germany will take at this time,” he said.
Blumenthal emphasized, “An expert evaluation of the medical case reports and all relevant scientific literature is needed to determine the extent of the problem and the appropriate steps for the proper labeling of kava.”
ABC and a coalition of trade associations of the dietary supplement industry are actively engaged in evaluating the information that has been made available by the German regulatory authorities. They have retained a highly regarded professional toxicologist from a leading university to ascertain the nature of the relationship between kava consumption and liver problems. The organizations include the American Herbal Products Association, the Council for Responsible Nutrition, the National Nutritional Foods Association, and the Utah Natural Products Alliance.
Based on the limited information made available to date, Blumenthal stated that consumers of kava should consider the following if they are using kava products:
- Kava should not be used by anyone who has any liver problems, or by anyone who is taking any drug product 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, Blumenthal suggests that kava not be taken on a daily basis for more than four weeks.
- In addition, Blumenthal noted that consumers should discontinue use if symptoms of jaundice (e.g., 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.
Blumenthal emphasized that the information now coming together on kava needs to be scientifically evaluated and addressed. And he noted this is being done by the FDA and the trade associations and that “These considerations and cautions represent a prudent approach to the information presently available.”
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.
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 safe and effective benefits of kava to relieve symptoms of anxiety were supported last year in a meta-analysis, a systematic statistical review of seven human clinical trials published in the Journal of Clinical Psychopharmacology and again in a similar critical review this year. The reviews did not find adverse effects related to liver toxicity.
Traditionally served as a beverage in social or ceremonial ritual in island communities of the south Pacific, kava (also known as kava kava, Piper methysticum) has been revered as the primary herb in these cultures (e.g., Fiji, Vanuatu, Samoa, Tonga) for possibly two or three millennia. Kava use in these cultures has been considered generally safe, with few adverse side effects.
“Historically, the scientific literature does not show much basis for concern about potential liver toxicity. These cases in Europe are relatively recent,” said Blumenthal who is also an associate professor at the College of Pharmacy at the University of Texas at Austin.
The primary adverse effects of kava reported in the literature are relatively minor and are usually associated with highly excessive intake. These effects include the occasional yellowing and scaling of skin, which returns to normal after discontinuation of the herb. Other effects associated with high doses include slow adjustments of the eyes to changes in light and impaired motor control (related to kava’s action of relaxing skeletal muscles, one of the reasons it is used for treating mild cases of anxiety).
Currently, kava ranks ninth in sales of all herbal dietary supplements sold in mainstream retail markets, with total mainstream sales in 2000 of approximately $15 million. This statistic does not include sales in health food stores, multi-level marketing companies, mail order, or sales by health professionals, which could account for an additional $15 million, or possibly more.
The American Botanical Council is the nation's leading nonprofit organization dealing with research and educational issues regarding herbs and medicinal plants. The 13-year-old organization occupies a 2.5 acre site in Austin, Texas where it publishes HerbalGram, a peer-reviewed journal on herbal medicine and other educational materials for consumers and healthcare professionals, including the highly rated The Complete German Commission E Monographs - Therapeutic Guide for Herbal Medicines (1998). Its new publication for health professionals, The ABC Clinical Guide to Herbs, will be published in spring 2002. Information contact: ABC at PO Box 144345, Austin, TX 78714-4345, ph: 512-926-4900, fx: 512-926-2345. Website: www.herbalgram.org.