Kava

Nutrition Forum, May, 1999 by Beth Fontenot

Controversial claims, questionable evidence

Who could resist a product that lures you with promises of relief from stress, feelings of relaxation and euphoria, enhanced mental alertness, and more harmonious feelings toward others--all legal, nonaddictive, and without the side effects of prescription antianxiety drugs. These are but some of the claims made by marketers of kava, an herbal product prorooted as an alternative to prescription tranquilizers such as Valium and Xanax. It is also touted as a pain reliever and treatment for insomnia and seizures.

Kava is the name for both the shrubby pepper plant that is native to the South Pacific Islands, and for the mildly narcotic beverage made from the crushed rhizome and roots of the plant. For centuries Islanders have ground the root into a powder, mixed it with water, and consumed it as a beverage. Kava drinks are used in the South Pacific much as alcoholic beverages are used elsewhere. In small doses, kava is supposed to reduce anxiety and relax muscles. Taken in large doses, it is intoxicating, causing drowsiness, nausea, muscle weakness, and blurred vision.

In the 1970s, kava was sold as a "street drug" through counterculture publications. Today, extracts from the root are placed in capsules, often combined with other herbal ingredients, and sold as a dietary supplement in supermarkets, "health-food" stores, and on the Internet. The ground root can also be purchased to create kava beverages. Last year Americans spent over $50 million on kava.

The primary active components in kava are called kavalactones, although there appear to be other active constituents as well. It is generally thought that the "beneficial" effects of kava are obtained through the use of root extracts because they contain the full range of the many components found in the root. How kava produces its effects in the brain is largely unknown, but it is thought to be through mechanisms other than those used by traditional sedative drugs. Some studies suggest that it may directly influence the limbic system, the part of the brain associated with emotions and other brain activities.

Questionable Studies

Five studies totaling several hundred people have been published in Europe comparing kava with a placebo for mild to moderate anxiety. Most of the study participants had been diagnosed with at least one anxiety disorder. The Hamilton Anxiety Rating Scale (HAMA), a standardized tool used in testing antianxiety drugs, was used to evaluate anxiety levels. In each study, those taking kava showed significant relief of their anxiety symptoms compared with those taking the placebo. The longest study, conducted at Jena University in Germany, showed after 24 weeks decreases in HAMA scores for both those taking kava and placebo. However, the kava-takers' scores were lower, indicating less anxiety (Pharmacopsychiatry. 1997 Jan.;30[1]: 1-5).

The reliability of these studies is questionable because people with mental or emotional disorders often feel better after taking anything at all, including inactive substances. In fact, in the Jena University study, three-fourths of the study participants reported significant improvement when taking kava, and half of those who took the placebo also reported feeling better. By the end of the study, nearly everyone reported feeling better than at the beginning of the study. Another problem with the reliability of the European studies is that it's unclear what the initial diagnoses of the subjects were.

An article in the Archives of General Psychiatry (1998 Nov.;551111:1033-1044) described the evidence for kava as a treatment for insomnia and anxiety as "opinions ... based on clinical experience, descriptive studies, or reports of expert committees." The evidence for kava's usefulness in seizure disorders was described as "insufficient ... to warrant conclusions about efficacy or safety."

Safety Issues

A serious concern with kava is that like most dietary supplements, the long-term effects are unknown. Therefore, it clearly should not be taken by children or teens or by pregnant or lactating women.

In addition, kava should not be combined with alcohol or other central nervous system depressants since it may increase their effects. In 1996, a Georgia man began taking kava as he weaned himself off Xanax. He became ill and slipped in and out of consciousness. His physicians identified the interaction between kava and Xanax as the culprit. Otherwise, little is known about how kava may interact with prescription medicines or other herbs like St. John's wort or valerian that also affect the central nervous system.

Another reported adverse reaction to kava is that it may interfere with dopamine and thus worsen Parkinson's disease, a condition of decreased dopamine activity in the brain. So patients with Parkinson's should not take kava. Also, at very high doses for long periods of time, biochemical abnormalities may occur (low levels of serum albumin, protein urea, and bilirubin), hypertension may develop, blood may appear in the urine, red blood cell volume may increase, platelet and lymphocyte counts may decrease, and shortness of breath may occur. Problems with equilibrium have also been reported.