Natural Foods Merchandiser

European Studies Link Kava To Liver Damage

Kava kava has come under scrutiny in Europe, Canada and the United States after the German government published studies on the herb's potentially hazardous effects on the liver.

In November, Germany's Federal Institute for Drugs and Medical Development (BfArM) reported 24 recent kava-related cases of liver damage, including one death. BfArM asked kava manufacturers to respond to the reports and stated that licenses to market the herb could be withdrawn.

Pharmaceutical giant Merck KGaA, based in Bonn, Germany, responded by pulling two kava-based products, Kytta-Kava and Kavadura, from German pharmacy shelves, despite other manufacturers' trust in the safety of this pepper plant known for its calming properties. Merck did, however, assert there have been no adverse effects from consumption of its products. Merck's annual kava sales in 2000 totaled about $443,000—a miniscule amount compared to its annual overall sales of $5.9 billion. U.S. kava sales in 2000 exceeded $30 million, reports the American Botanical Council in Austin, Texas.

Mark Blumenthal, executive director of the ABC, said that the German government is considering withdrawing the herb, "because kava is not approved as a herbal drug by the same standards as conventional drugs, the perception of its risk is increased because its benefits are not as strongly documented as [with] conventional drugs."

Although the German authority will not decide the herb's status until early 2002, the industry alert has already resulted in the ban of kava product sales in France and the suspension of sales in England.

"As a precautionary measure, we have asked all retailers and manufacturers to withdraw kava from sale," says Maurice Hanssen, director of the U.K.-based Council for Responsible Nutrition.

Despite the withdrawal, Hanssen is optimistic that the product will soon be back on the shelves, noting, "The German dosage seems incredibly high compared to other parts of the world." He says the situation is a result of unsubstantiated or inappropriate scientific evidence presented to authorities.

Canada is also considering pulling kava from the shelves, while the Belgian government has issued a warning about kava.

In the United States, the FDA responded by announcing an investigation into kava's potential liver toxicity. In December, the FDA requested the assistance of health care professionals in reviewing and reporting cases of liver toxicity to determine if any may be kava related.

Michael McGuffin, president of the Silver Spring, Md.-based American Herbal Products Association, said the FDA request will probably generate "hundreds of responses, a huge list of anecdotes, and a lot of it will be bad. I mean bad in both ways: Some will improperly implicate kava, and all of it will generate bad publicity." McGuffin said the AHPA supports stronger labeling, but not removing products from the market—unless reports come back that conclusively show kava is harmful to consumers.

"No reports of adverse liver effects of kava have been published in the U.S.," Blumenthal said. "Despite the relatively good safety profile that kava has in the U.S., we need to take this action by the German government seriously. 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."

The ABC and a coalition of dietary supplements industry associations, including the AHPA, the CRN, the National Nutritional Foods Association and the Utah Natural Products Alliance, is currently evaluating the information released by the German government. The coalition is working with a university toxicologist to determine if there is a link between kava and liver problems.

Based on the German adverse events reports, the ABC recommends that kava consumers consider the following:

  • Kava should not be taken by anyone with liver problems, by anyone taking drugs with known adverse liver effects, or by anyone who drinks alcohol regularly.

  • Reports so far deal with chronic use, so Blumenthal suggests that kava not be taken daily for more than four weeks without professional supervision.

  • Consumers should discontinue use if symptoms of jaundice (i.e., dark urine, yellow eyes) occur.

  • Consumers should consult their health care provider if they have liver problems or suspect any new problems.

Shane Starling is a contributing writer for Functional Foods & Nutraceuticals.

Natural Foods Merchandiser volume XXIII/number 2/p. 1, 10

New Studies Support Kava For Anxiety

Two new studies conducted at Duke University Medical Center show kava kava extract is safe and as effective as prescription drugs for treating stress and anxiety. These studies add to a growing body of science on kava. Kava's activity is caused by the plant's resinous compounds, called kavalactones.

Both Duke studies used a standardized kava extract. In one study, researchers Kathryn Connor, John Davidson and Erik Churchill found, "Kava has several advantages over conventional pharmacologic treatments for anxiety—in clinical settings kava has been associated with better tolerability and lack of physiologic dependence and withdrawal."

In safety tests, the researchers found no problems with kava extract. Examining withdrawal symptoms, heart rate, blood pressure and sexual function, kava extract tested as safe as placebo.

In the second study, researchers Lana Watkins, Connor and Davidson found that kava extract improves baroreflex control of heart rate in patients with anxiety disorder. According to the researchers, "Anxiety disorders are associated with low vagal control of heart rate and increased risk of cardiac mortality and sudden cardiac death." They further noted, "... improving vagal control prevents the occurrence of lethal dysrhythmias in clinical studies."

Kava extract proved to be an effective antianxiety agent, and also increased baroreflex control. This finding suggests that kava extract may reduce a cardiac risk factor. Further studies are needed to repeat this effect.

The Duke researchers concluded that kava can be used to effectively treat anxiety at 280 mg of kavalactones per day.

Chris Kilham teaches ethnobotany at the University of Massachusetts at Amherst.

Natural Foods Merchandiser volume XXIII/number 2/p. 10

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