Hot on the heels of St.-John’s-wort’s popularity in treating depression, a new herbal star has risen to ease another modern woe: anxiety.
Kava, also called kava-kava, is made from the rootstock of a South Pacific plant, Piper methysticum. Used for hundreds of years in religious and social rituals of the Pacific Islands, kava is a relative newcomer to the United States—with a number of clinical studies confirming its use in relieving stress.
Kava has been known to Westerners since 1768, when Daniel Carl Solander, a botanist on Captain James Cook’s first expedition around the world, found a plant in the South Pacific he called “Piper inebrians.” That name passed into obscurity as a footnote in a journal, along with the notation, “The expressed juice of this plant they drink to intoxicate themselves.”
Kava’s scientific moniker, Piper methysticum Forst., comes from Johann Georg Adam Forster, who accompanied Cook on his second expedition around the world from 1772 to 1775. Forster published the name Piper methysticum in a book that appeared in 1786.
What is kava?
Piper methysticum is in the genus Piper in the pepper family (Piperaceae), the group to which black pepper (Piper nigrum) belongs. Piper is a large plant group, whose more than 1,000 species include shrubs, high-climbing woody vines, and even small trees. Kava is a highly variable shrublike herb that usually grows to about 6 feet but can reach 20 feet given lush soil and good sunlight. The bright green, heart-shaped leaves are 6 to 8 inches long. Its small flower spikes are sterile.
Kava plants must be propagated by dividing the roots. The succulent, thick stems have strongly swollen nodes, which vary in color from green to black. More than a dozen types of kava are known in Hawaii, at least five in Fiji, several in New Guinea, and nine in Samoa. On the islands of Vanuatu, where kava is heavily used, the indigenous people have identified more than seventy varieties.
Based on more than 3,000 years of use, Polynesian islanders have ensured the plant’s survival by carefully preserving varieties whose active ingredients are particularly flavorful and strong. Kava is not known to occur in the wild. It is a cultigen, a plant selected and grown for the benefit of humans. Because it does not produce viable seed, it must be propagated vegetatively.
Sometimes called “the water of life,” kava is deeply entwined with cultural and spiritual traditions in the South Pacific, where the herb has been used for centuries to make a ceremonial beverage. Origin myths honor kava’s role in sexuality, fertility, and regeneration. Ceremonial kava drinking evokes fellowship and symbolizes the strength and continuity of social harmony.
Kava’s cultural role has been likened to that of red wine in France, though kava takes on a much deeper spiritual significance.
Kava in the West
Although kava is relatively new to the U.S. herb market, it was used in Germany to treat urinary tract ailments and gonorrhea as early as 1850. Kava extracts were common in German herb shops by the end of the century. By the 1920s, tinctures were available in Germany for use as a mild sedative. Much of the modern chemical, pharmacological, and clinical research on kava has been conducted by German scientists.
The primary active constituents of kava are known as pyrones, collectively called kavalactones or kavapyrones. These chemical compounds are responsible for the herb’s anxiety-easing and muscle-relaxing effects. Pharmacological studies have shown that two of these compounds, dihydrokavain and dihydromethysticin, have an analgesic effect comparable to aspirin. The slight numbing sensation that kava produces in the mouth is primarily the result of the kavalactone kavain.
As market and consumer interest in kava grows, so does scientific interest. From 1989 to 1995, six controlled clinical studies involving about 500 patients were conducted on the use of kava products. Four dealt with the treatment of anxiety syndrome, and two studied kava’s effects on menopausal symptoms. Dosage ranges from 30 to 210 mg per day, but most studies involved a dosage of 210 mg per day. Studies show that kava is comparable in effectiveness to the class of drugs known as benzodiazepines, but without the side effects of physical or psychological dependency.
In 1996, researchers in Dusseldorf, Germany, completed a double-blind placebo-controlled study of kava-root extract on patients with anxiety syndrome. Patients were given either a placebo or three daily doses of a 100 mg kava extract for four weeks. Those given the kava preparation showed a significant reduction in symptoms after only one week. Positive effects increased throughout the following three weeks, and no adverse reactions were observed. The researchers concluded that the kava preparation is suitable for general practitioners to use in treating anxiety and tension.
Adopted by German phytomedicine, kava is approved for treatment of “conditions of nervous anxiety, stress, and restlessness.” However, the social and medical implications of kava use are extremely complex. There is potential for abuse.
The field of toxicology is governed by the axiom “the dose makes the poison.” This is certainly true for kava. In German phytomedicine, the daily dose is expressed as equivalent to 60 to 120 mg of standardized kavapyrones (kavalactones). In the United States, kava capsules generally contain 400 to 500 mg of dried, powdered root, but because they may not be standardized, consumers can’t be certain how many pyrones the capsules contain.
For liquid preparations such as tinctures (alcohol extracts, 1 g per 5 ml in 60 percent ethanol), dosage ranges from 15 to 30 drops up to three times daily. Standardized products, mostly from European manufacturers, contain up to 70 percent kavapyrones (kavalactones), delivered in 210 mg daily doses, divided into three portions. It is very important to follow label instructions when using kava products.
In traditional Polynesian cultures where many people drink large amounts of a thick kava brew over long periods of time, skin sores and temporary yellow discoloration of the skin, nails, and hair have been observed. In rare cases, kava use has led to allergic skin reactions, enlarged pupils, and disturbances of visual equilibrium. These symptoms appeared after subjects drank up to thirteen quarts of kava brew a day, equivalent to ingesting about ten to fourteen ounces of powdered kava root in a week.
Westerners should be aware that kava can interact with alcohol, barbiturates, and psychopharmaceuticals. It is generally contraindicated during pregnancy, lactation, and treatment for certain forms of depression. In Germany, labels on kava products warn consumers not to operate motorized vehicles or heavy equipment while taking even normal dosages. Kava’s active components affect the muscles’ ability to contract. During an overdose, the mind remains sharp but one can lose muscle control.