Kava, or Piper methysticum, is a plant root frequently used to lessen anxiety. It is well-known in South Pacific cultures as a ceremonial drink. Kava has become a controversial botanical remedy due to reports of potentially serious side effects, including liver damage. Previously, results of scientific studies on kava and the liver were contradictory or inconclusive. Theories exist concerning problems with kava extraction methods, kava root contamination and plant varieties. As a result, its sale and use are banned in many countries, but kava is not yet banned in the United States. The latest research, however, suggests that kava may indeed contain a chemical that is harmful to the liver.
Reports of Liver Damage
In 2002 and 2003, Germany and the United Kingdom, respectively, banned the sale of kava due to increasing concerns about liver damage. Other countries have since banned it. Mixed research data exists surrounding kava and reports of liver toxicity, says Professor Edzard Ernst, of Peninsula Medical School at the Universities of Exeter and Plymouth in the U.K., in the October 2007 issue of the "British Journal of Clinical Pharmacology." Apparently liver damage due to kava consumption has not been a concern among people in the South Pacific, in spite of its use for generations. Ernst notes the idea of possible contamination of the kava root with different parts of the plant as being one possible cause of toxicity. Furthermore, he says, there were growing arguments about the safety of the traditional water-based kava extracts versus the newer solvent-based ones.
Water-Based Kava Extract
Lucie Rychetnik and Christine M. Madronio reviewed articles published between 1987 and 2008 that examined the effects of drinking kava extracts produced by soaking kava root in water. Their findings appeared in the January 2011 issue of "Drug and Alcohol Review." Obtaining a kava drink by soaking the roots in water is the traditional way of getting the extract in South Pacific cultures. Two studies they reviewed did not support that this aqueous form of kava causes liver damage. One study, published in September 2003 in the "European Journal of Gastroenterology and Hepatology" found elevated levels of the liver enzyme gamma glutamyl transferase in heavy drinkers of kava, but researchers noted that the presence of this enzyme did not mean there was any liver damage. The other study, published in the "Journal of Toxicology-Clinical Toxicology" in October 2003, also found that consuming water-based extracts of kava did not cause liver damage.
Kava Extraction and Plant Varieties Scrutinized
The November 2010 issue of the "Journal of the American Medical Association" published an article by Rolf Teschke and Johannes Schulze regarding concerns issued in 2002 by the U.S. Food and Drug Administration about kava. This article notes other research supporting that both water-based extracts of kava and also solvent-based extracts could cause liver damage. The current research was pointing to a substance known as flavokawain B, as the main liver poison, they said. Contradictory research findings from different studies led to the theory that certain varieties of the kava plant may be more suitable for making kava extracts. Some kava plants may contain more flavokawain B than others. The authors suggest that kava plant quality control is needed, considering previous evidence that some kava varieties can be used safely under certain conditions.
The Danger of Flavokawain B
Experimental results published in the December 2010 issue of the "Journal of the Federation of American Societies for Experimental Biology" found that flavokawain B will kill liver cells. Flavokawain B, or FKB, as it is known, exists in the kava root. According to the study, use of a solvent such as alcohol or acetone to get the kava root extract, will result in a product containing high levels of flavokawain B. Researchers concluded that FKB is dangerous in kava products, and occurs in higher concentrations in solvent-based extracts. These researchers suggest that the amount of FKB in kava extracts sold to consumers should be monitored and controlled to avoid causing liver damage.
Based on the current research, kava products are not safe when the medicinal or psychoactive compounds of the kava root are extracted using solvents. This does not mean that water-based kava extracts are always safer alternatives. Quality of the kava plant extract you are buying may not be easily known. You should use extreme caution when using kava products, or avoid them completely. Be aware that liver damage is only one possible side effect of kava. Other side effects may include loss of appetite, nausea and skin rash.