Kava has been used in ceremonies and for recreational and social purposes in the South Pacific since ancient times, much like alcohol, tea or coffee is in other societies today.
In the 1980s other medicinal uses for kava began to emerge 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.
More recently, evidence began to emerge about the adverse affect kava could have on the liver and serious concerns about the dangers of kava and the effects on the liver have resulted in regulatory agencies, such as the US Food and Drug Administration and Australia's Therapeutic Goods Administration, banning or restricting the sale of kava and kava products.
Originally from Fiji, where kava drinking is common, Professor Iqbal Ramzan, Dean of Pharmacy at the University of Sydney, Australia, had previously published articles on the adverse effects of kava, and wanted to investigate further the effects kava had on the liver. Leading a team of researchers from the University of Sydney, Professor Ramzan spent one year investigating the cellular effects of kava on the liver.
To test these theories, the University of Sydney study focused on the major kavalactone (the ingredient in kava believed to affect the liver) -- kavain -- and investigated the effects it had on the ultrastructure (or biological structure) of the liver.
This required the use of electron microscopes (which enable the examination of the interior of cells) provided by the Australian Key Centre for Microscopy and Microanalysis at the University of Sydney under the direction of its Deputy Director, Professor Filip Braet.
The study 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.
In other words, the kavain treatment disturbed the basic structure of the liver, consequently seriously impacting the normal functioning of the liver.
The results of the University of Sydney's study clearly support earlier literature observations on kava's adverse affects on the functioning of the liver in general.
However, additional investigations into the effects of other major kavalactones on the liver, as well as studies on whether the effects of kava are reversible, are urgently needed.
Reference: 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