Kava: Is It Safe?
By Hyla Cass M.D.
The South Pacific herb, Kava Kava, is a best-seller — ranking ninth in retail U.S. sales in mainstream markets in 2000 — based on its proven ability to relieve stress, anxiety and tension. Recently kava has come under the scrutiny of the United States Food and Drug Administration (FDA), which is acting on reports from Europe that kava may damage the liver.
The agency noted that German and Swiss health authorities have identified approximately 30 cases of sometimes-serious liver toxicity, including four cases requiring transplantation, and one death, that are believed to be associated with kava consumption.
Based on these reports, the U.K. has banned sales of kava products and German authorities have notified manufacturers of kava products that their licenses to market the herb could be withdrawn.
The Evidence So Far
Closer examination of the scant details available on the 30 European cases reveals that the vast majority, 21 cases in all, involved the concomitant use of hepatotoxic drugs and/or alcohol. This is not significant evidence of hepatotoxicity.
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.
The fact is, you are far likelier to suffer from liver damage by taking the prescription anti-anxiety drug, Valium, as you are kava, yet it is taken by millions daily with little question-and with no major adverse publicity. The over-the counter pain medication, acetominphen (Tylenol), also has a high incidence of liver toxicity, especially when combined with alcohol.
Kava has a long traditional use in the South Pacific at often considerably higher doses than those used in Europe i with few reported liver toxic effects, and its safety/toxicity has been studied extensively in recent
years. 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 longest running study conducted to date, with 101 people for 6 months taking 70mg 3/day had negligible side effects, and in fact, more of the placebo subjects reported side effects than those taking kava. The researcher concluded that, "in contrast to both benzodiazapines and antidepressants, kava possesses an excellent side-effect profile."
ii The safe and effective benefits of kava to relieve symptoms of anxiety were also supported in a meta-analysis, a systematic statistical review of seven human clinical trials published in 2000 in the Journal of Clinical Psychopharmacology, and again in a similar critical review in 2001. The reviews did not find significant adverse effects related to liver toxicity.
The Industry Response
There has been a strong response by the herbal industry to ensure kava's safety. "We are actively proceeding with a number of initiatives on this issue, both within and outside the industry, working jointly with regulators and the scientific community to learn as much as we can about these adverse events and the safety of kava," said John Cardellina, Ph.D., Vice President for Botanical Sciences, Council for Responsible Nutrition.
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.
Mark Blumenthal of the American Botanical Council emphasized that the information now coming together on kava needs to be scientifically evaluated and addressed. And he noted this is being done by FDA and the trade associations and that "These considerations and cautions represent a prudent approach to the information presently available."
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 considering that kava not be taken on a daily basis for more that four weeks. (Note: We consider that to be overly conservative, preferring the German Commission E's recommendation of 3 months.)
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.Another possible recommendation is to set maximum doses allowable for kava, given that adverse reactions have been reported in Germany where high doses, above recommended levels, are routinely prescribed. Australia has such a system - with a maximum 125 mg kavalactones per tablet or capsule, 3g of dried rhizome per teabag and 250mg kavalactones maximum daily dose for all forms.
The FDA's Medwatch Program
The FDA has sent a letter to doctors requesting that any adverse events associated with the use of kava products be promptly communicated to FDA's "Medwatch Program." The letter also noted that there were several incidents of "serious injury allegedly associated with the use of kava-containing supplements." There are however, some problems inherent in this reporting system, explained in the box, "Clarifying FDA Allegations."
Clarifying FDA Allegations
The Medwatch site contains numerous "kava toxicity" reports of cases due to a product sold at a 1996 New Years Eve rave (dance) event, alleged to contain kava, but in fact, contained a highly toxic industrial chemical, called 1,4-butane-diol -- and absolutely no kava. The Los Angeles police department toxicologists within weeks published a report to this effect. Nonetheless, these spurious claims against kava have remained on the FDA website ever since.
In general, anyone can report anything to Medwatch: no proof of actual content is required for a posting, which does not protect the public from the truly bad products, but may, as in this case, wrongfully malign others.
In conclusion: More thorough investigation is needed before we can draw any conclusions about kava's potential toxicity. The entire issue also points out the importance, and vulnerability of the liver, the chemical factory that is the site of metabolism of many of the essential body compounds, and the detoxification center for ingested chemicals. Ironically, while the topic here is the potential hepatotoxicity of an herb, the plant kingdom provides us with such life-saving liver-protective herbs as milk thistle.
In fact, in my own clinical practice, I will add it to the regimen of those who are or have been on drugs that affect the liver, for protection and restoration of its vital function.
The current situation does point out that the liver is affected by many substances, including prescription and non- prescription drugs, as well as alcohol, which is a major cause of liver damage.
We must be aware that herbs are potent medicines, to be treated with the appropriate respect regarding potential interactions and toxicity, including to the liver. On the other hand, kava's margin of safety far surpasses that of it's pharmaceutical equivalent.
Nothing would be gained by previously satisfied consumers of kava, out of fear of these potential side effects, switching to a more toxic prescription medication, such as a benzodiazepine, in the mistaken belief that they were making a safer choice.
Hyla Cass, MD
Author of Kava: Nature's Answer to Stress, Anxiety, and Insomnia
i Lichtwer Pharma AG Formulation data sheet, November 1998 Lebot V. et al.,Kava: The Pacific Drug, Yale University Press, 1992, Page 200
ii Volz et al., 1997, Kava Kava extract WS 1490 versus placebo in anxiety disorders - a randomized placebo controlled 25 week outpatient trial', Pharmacopsychiatry 30(1), p1-5.
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