Mark BlumenthalAustin, 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kava manufacturers that licenses to market the herb could be withdrawn by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, 2001 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
non-profit 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number of adverse events in its unpublished database.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:
anyone who is taking any drug products with known adverse effects on the
liver, or anyone who is a regular consumer of alcohol.
suggests that kava not be taken on a daily basis for more than four weeks.
if symptoms of jaundice (e.g., dark urine, yellowing of the eyes) occur.
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 non-profit
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:
http://www.herbalgram.org.
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Mark Blumenthal
Founder & Executive Director
American Botanical Council
http://www.herbalgram.org
Jim Strohecker
Daniel Redwood DC