Kava Unjustly Banned?

In 2002, after several reports of severe liver damage associated with the consumption of kava, the US Food and Drug Administration (FDA) issued precautionary letters to physicians and consumers regarding the use of this herbal supplement. Several other countries, including Germany, France, Switzerland, Canada, and Australia, restricted the sale of kava-containing products due to reports of hepatotoxicity.

In spite of FDA warnings, kava has remained extremely popular in this country; it is most frequently used to treat anxiety, stress, insomnia, premenstrual symptoms, and depression. Though the warning remains in effect, and many respected sources echo the FDA’s concerns, researchers have revealed some weaknesses in the rationale behind the advisory.

Traditional Use

For over two millennia, kava has been ingested by Pacific islanders without any known ill effects. The herb was found on most islands in the South Pacific at the time of first contact with Europeans. Prepared as an aqueous infusion (tea), dried kava root was used in ceremonial rituals and for treating a wide range of medical conditions. The exclusive use of the plant’s root, as well as its method of preparation, may have been responsible for the lack of documented toxicity from the consumption of this herb among indigenous peoples.

In contrast, many commercial extracts have been prepared with alcohol, acetone, or even chloroform. Aside from being hepatotoxic, these solvents could introduce additional toxic material into the products. Furthermore, it is now known that some of the preparations implicated in instances of toxicity contained extracts of leaves and stems; these plant parts contain toxic compounds that are not found in the root.

Further Evidence of Safety

At least eight toxicological studies have been performed on kava extracts and on kavalactones, the active ingredients of the plant. The effects of kava on human liver cells in vitro have also been evaluated. None of these investigations have shown any evidence of hepatotoxic effects, nor are there reports of liver damage associated with long-term kava use in the ethnopharmacological literature.

Faulty Data

In addition to the presumed contamination that led to some cases of toxicity, it seems likely that the methodologies used to report these incidents were suspect. A number of independent reviews have shown noncompliance with established guidelines for reporting adverse events.

In one analysis, out of 36 reported events, only one case showed a causal relationship between toxicity and kava dosages that were in conformance with German Commission E standards. Three other cases may have been related to excessive doses. The authors of this review noted that “the allocation of kava (to toxicity) is not logical in the majority of cases and appears arbitrary.”

One example of inconsistency mentioned by these same experts involved a fatality where it was known that many years of alcohol abuse—not the use of kava—was the cause of liver failure. Indeed, autopsy revealed chronic cirrhotic changes that began before kava was ever ingested.

In 2002, after evaluating available data, Donald Waller of the University of Illinois at Chicago College of Pharmacy concluded that there is "no clear evidence that the liver damage reported in the United States and Europe was caused by the consumption of kava."

Recommendations

Research supports the use of kava for mild-to-moderate generalized anxiety disorder; evidence supporting other uses is currently not available. Since the FDA’s advisory still holds, and since concerns still exist over the potential for hepatotoxicity with kava use, it seems prudent to consider the following guidelines:

1. Individuals with a history of liver problems should avoid kava
2. Dosage should be limited to less than 300 mg daily
3. Kava should not be combined with other agents that undergo extensive hepatic metabolism (alcohol, medications, other herbal supplements)
4. Only root-containing preparations should be used
5. Only standardized extracts (WS1490) should be consumed
6. Use should be limited to 24 weeks

For more information, go to: www.nccam.nih.gov/health/kava/

Kava Plant

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