Kava first piqued scientific interest during the mid-1800s, when researchers traced kava's relaxing properties to kavalactones, which are found in its root and relax muscles without blocking nerve signals that keep the muscles tense. This may explain how kava can relax muscles without numbing the thinking process. But kava's mind-altering action has largely been ignored in modern times due to the development of synthetic psychopharmaceuticals, including antidepressants. Recently, however, kava and other plant therapies have received more attention because undesirable side effects, including addiction, can make some synthetic drugs unsuitable for long-term treatment.

What science says about kava
Kavalactones have been shown to relieve anxiety and pain and relax muscles in laboratory animals. In humans, they have been shown to change brain activity (as measured by an electroencephalogram) without sedation. A recent study showed that people taking measured doses of a kava extract fared better in word-recognition tests than those taking a synthetic tranquilizer (benzodiazepine), and a 1993 report in the British Journal of Phytotherapy referred to kava as one of few herbs that can safely relax skeletal muscle. The report's author recommended it for treating nervous tension and conditions associated with skeletal muscle spasms, such as headaches caused by a tense neck.

In 1996, a randomized, placebo-controlled, double-blind study showed that kava significantly reduced anxiety in humans. Two groups of twenty-nine people with normal anxiety were treated for four weeks with three daily doses of 100 mg of kava rhizome extract or a placebo. After one week of treatment, members of the kava group had significantly lower anxiety levels compared with that of the placebo group, and the difference between the two groups increased during the course of the study. No adverse reactions to the kava extract were noted during the study.

A 1995 report, however, described four patients who experienced unpleasant side effects from using various kava preparations. A twenty-eight-year-old man, who had been taking pharmaceuticals for treatment of anxiety, had sharp spasms in the muscles of his neck and eyes that began about ninety minutes after taking 100 mg of kava extract and lasted about forty minutes. A twenty-two-year-old woman experienced a similar reaction to the same product but denied taking any other medication, as did a sixty-three-year-old woman who had taken 150 mg of kava extract three times daily for four days to treat anxiety. Finally, a seventy-six-year-old woman with early signs of Parkinson's disease (a disorder of the nervous system) reported a pronounced increase in the duration and number of episodes of impaired movement after switching from pharmaceuticals to 150 mg of kava extract, which she took twice a day. The study's authors suggested that kava products be used cautiously, especially in the case of elderly patients.

Symptoms: Anxiety, insomnia, stress

Dose: Standardized extracts used in clinical studies have a dosage of 100 mg per day divided into three portions. Otherwise, follow the instructions on the product label or those of your health-care provider.

Preparations: Kava-root tablets, capsules, tinctures, kava-leaf products, and dried root are available in American health-food stores. Standardized European products contain 70 percent kavalactones.