Kava kava is a dioecious (having male and female reproductive parts of the plant on different individuals) shrub native to the Pacific islands. Its botanical name is Piper methysticum ; it is a member of the Piperaceae, or pepper, family. It is also known as asava pepper or intoxicating pepper. The narcotic drink made from the roots of this shrub is also called kava kava. Kava kava has been widely recommended in recent years as a mild tranquilizer due to its painkilling properties. As of 2002, however, kava kava has been the subject of official safety warnings from the U. S. Food and Drug Administration (FDA) and its counterparts in Canada, France, Germany, Switzerland, and Spain.
Captain James Cook is credited with introducing kava kava to Europeans when he visited the South Pacific in 1773. Previously, the inhabitants of the Pacific islands used kava kava as a ceremonial beverage. It was consumed at weddings, funerals, and birth rituals, and it was offered to honored guests. Kava kava was also drunk as part of healing rituals. The first commercial products containing kava kava were offered to European consumers around 1860.
As of 2001, kava kava ranked ninth in sales of all herbal dietary preparations sold in the United States through mainstream retailers, with total sales of $15 million. Health food stores, health professionals, and mail order firms accounted for another $15 million in sales of kava kava.
The German Commission E, a panel of physicians and pharmacists that reviews the safety and efficacy of herbal preparations, at one time approved the use of kava kava as a nonprescription dietary supplement for the relief of nervous anxiety, stress , and restlessness. That approval was withdrawn in the fall of 2001.
In addition to relief of stress and anxiety, kava kava has also been recommended by health care providers for insomnia , sore or stiff muscles, toothache or sore gums, attention-deficit/hyperactivity disorder , menstrual cramps, uncontrolled epilepsy, and jet lag.
The beverage form of kava kava was traditionally prepared in the Pacific islands by chewing the roots of the kava plant and spitting them into a bowl. The active compounds, known as kavalactones and kavapyrones, are found primarily in the root of the plant and are activated by human saliva. Contemporary Pacific islanders prepare kava kava by pounding or grinding the roots and mixing them with coconut milk or water. Modern Western manufacturers use alcohol or acetate in making liquid kava preparations. Kava kava is also available in capsules, tablets, powdered, or crushed forms. Experts in herbal medicine recommended the use of kava preparations standardized to contain 70% kavalactones.
Kavalactones are chemicals that affect the brain in the same way as benzodiazepines such as valium, which is prescribed for depression or anxiety. Kavalactones cause the tongue or gums to feel numb. Kavapyrones are chemicals that have anticonvulsant and muscle relaxant properties.
Kava kava should never be given to children, particularly in view of recent health warnings concerning adults.
The usual dose of kava kava that has been recommended to relieve stress or insomnia in adults is 2–4 g of the plant boiled in water, up to three times daily. Alternately, 60–600 mg of kavalactones in a standardized formula could be taken per day.
Before 2002, the usual precautions regarding kava kava stated that it should not be used at all by pregnant or lactating women, or by any individual when driving or operating heavy machinery. The American Herbal Products Association (AHPA) advised consumers in 1997 not to take kava kava for more than three months at a time, and not to exceed the recommended dosages. In light of more recent findings, however, it may be prudent to completely avoid preparations of or products containing kava kava.
Prior to 2002, most reports of side effects from kava kava concerned relatively minor problems, such as numbness in the mouth, headaches, mild dizziness, or skin rashes. In the nineteenth-century, missionaries to the Pacific islands noted that people who drank large quantities of kava kava developed yellowish scaly skin. A recent study found the same side effect in test subjects who took 100 times the recommended dose of the plant.
As of 2002, kava kava has also been associated with causing damage to the liver, including hepatitis, cirrhosis, and liver failure. Most of the research on kava kava has been done in Europe, where the herb is even more popular than it is in the United States. By the late fall of 2001, there had been at least 25 reports from different European countries of liver damage caused by kava kava; French health agencies reported one death and four patients requiring liver transplants in connection with kava kava consumption. On December 19, 2001, the Medwatch advisory of the FDA posted health warnings about the side effects of kava kava; on January 16, 2002, Health Canada advised Canadians to avoid all products containing the herb. France banned the sale of preparations containing kava kava in February 2002. The U. S. National Center for Complementary and Alternative Medicine (NCCAM) has put two research studies of kava kava on hold while awaiting further action by the FDA. NCCAM advised consumers in the United States on January 7, 2002, to avoid products containing kava.
In addition to causing liver damage, kava kava appears to produce psychological side effects in some patients. A team of Spanish physicians has reported that beverages containing kava kava may cause anxiety, depression, and insomnia. In addition, kava kava may cause tremors severe enough to be mistaken for symptoms of Parkinson's disease.
Kava kava has been shown to interact adversely with beverage alcohol and with several categories of prescription medications. It increases the effect of barbiturates and other psychoactive medications; in one case study, a patient who took kava kava together with alprazolam (a benzodiazepine used to treat anxiety) went into a coma. It may produce dizziness and other unpleasant side effects if taken together with phenothiazines (medications used to treat schizophrenia ). Kava kava has also been reported to reduce the effectiveness of levodopa, a drug used in the treatment of Parkinson's disease. To avoid potential reactions with prescription medications, people should inform their physician if they are taking kava kava.
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NIH Office of Dietary Supplements. Building 31, Room 1B25. 31 Center Drive, MSC 2086. Bethesda, MD 20892-2086. (301) 435-2920. Fax: (301) 480-1845. <www.odp.od.nih.gov/ods> .
American Botanical Council (ABC). P.O. Box 144345, Austin, TX 78714-4345. (512) 926-4900. Fax: (512) 926-2345. <www.herbalgram.org> .
FDA Center for Food Safety and Applied Nutrition. <www.fda.gov/medwatch/safety/2001/kava.htm> .
NIH National Center for Complementary and Alternative Medicine (NCCAM) Clearinghouse. P. O. Box 8218, Silver Spring, MD 20907-8218. TTY/TDY: (888) 644-6226. Fax: (301) 495-4957. <www.nccam.nih.gov> .
Rebecca J. Frey, Ph.D.