More evidence has surfaced about the adverse affect kava could have on the liver. Kava is an herb which has been used in ceremonies and for recreational and social use in the South Pacific for around 3000 years, akin to the status of alcohol, tea or coffee in other societies today.
Researchers from the University of Sydney have published a new study  investigating effects of kavain, one of the main active ingredients of kava, on the biological structure of the liver.
In the 1980s additional medicinal uses for kava began to become known, and it was marketed in herbal form as a natural way to treat conditions such as anxiety, insomnia, tension and restlessness, particularly in Europe and North America.
Kava Kava Safety
Concerns about the safety of commercial kava products were first raised in 2001[2,3], and included claims of liver toxicity, with liver failure in some people who had used dietary supplements containing kava extract. The concerns have resulted in regulatory agencies, such as the US Food and Drug Administration banning or restricting sale of kava and kava products.
The study made use of electron microscopes, which enable the examination of the interior of cells. The researchers found that following kavain treatment the liver tissue displayed an overall change in structure, including the narrowing of blood vessels, the constriction of blood vessel passages and the retraction of the cellular lining.
Interestingly, kavain also adversely affected certain cells which function in the destruction of foreign antigens (such as bacteria and viruses), which make up part of the body’s immune system. Essentially, the kavain disturbed the basic structure of the liver, thus seriously impacting normal functioning of the liver.
Politics of Kava Research
The issue of kava safety has always been a controversial one. Debate is fueled by conflicting cultural and economic interests. Big pharmaceutical companies are likely worried about competition among anti-anxiety drug sales.
Kava-exporting nations in the Pacific Islands have an obvious stake. There are also the usual disagreements between the medical establishment and practitioners of herbal and alternative medicine. In traditional use in the South Pacific, the kava plants stem peelings and leaves are discarded, and only the roots are used and extracted with water.
Since there is no standard for medicinal grade of bulk kava, the stems and leaves could be part of the preparation sold in the health food stores. Could this explain why the traditional users experience side effects that are mild, temporary, and confined to the skin, while industrialized countries that have newly adopted kava occasionally show severe, acute responses?
It is also interesting to note that kava consumption has been correlated with decreased incidences of cancer. No doubt the debate will continue with study results favorable to each side.
Fu S, Korkmaz E, Braet F, Ngo Q, Ramzan I. Influence of kavain on hepatic ultrastructure World J Gastroenterol 2008 January 28; 14(4): 541-546
Mark Blumenthal (2002). Kava safety questioned due to case reports of liver toxicity American Botanical Council. HerbalGram
United States Centers for Disease Control and Prevention (2002 Hepatic Toxicity Possibly Associated with Kava-Containing Products — United States, Germany, and Switzerland, 1999-2002 Morbidity & Mortality Weekly Report 51(47): 10651067
Steiner, G G (2000). The correlation between cancer incidence and kava consumption Hawaii Med J. 2000 Nov;59(11):420-2
Illustration: Wellcome Library, London. A gathering at the ceremonial drinking of kava in the Friendly Islands. Lithograph by A. Noël after de Saison.