Kava is the term used for both the plant and the beverage made from it. The beverage is prepared from the root of a shrub called the pepper plant, Piper methysticum, found in Polynesia, Melanesia, and Micronesia. The kava root is ground to a powder, and it has a brownish color. The brownish powder is then mixed with water and drank as a beverage, without being fermented. Extracts from the kava root are now placed in capsules and sold as kava or kava kava.

In the last few years there have been several reports of individuals in Europe with liver damage while consuming kava on a regular basis. A few reports of liver damage occurring in kava users in the US have also been mentioned in the media. As of now, there have not been any scientific published studies that have proven liver damage occurs in subjects consuming kava. There are many individuals in the Pacific islands who consume kava on a daily basis for almost a lifetime with no apparent liver damage reported. Drinking kava has been part of their culture for hundreds of years. Kava, traditionally consumed in the Pacific as water extracts, has been found to contain far less kava lactones than what is present in kava capsules.

My preliminary assessment is that it is possible that the liver damage in some individuals was due to kava. However, it is possible that kava was not the culprit, or the only culprit. Some of those who have been found with liver damage were taking other medicines along with the kava, or were very very old. Perhaps kava is harmful to the liver if combined with certain medicines. Maybe some of them abused alcohol or had a history of hepatitis. It is also possible that the extraction method to make kava capsules in Europe is different than that in the US which explains more cases reported in Europe than in the states. Europeans extract the kava lactones by hexane or acetone, and make their product contain 70% kava lactones while in the US, most products are 30 to 55% kava lactones. Another possibility is that there may be individuals who have a genetic predisposition to have an unusual liver toxic reaction to kava. New research done in Hawaii indicates a toxic chemical (pipermethystine) may be present in the stem peelings and leaves of the kava plant but not the root. As the demand for kava increased a few years ago, companies started buying the stem peelings and leaves along with the root while traditional kava users on the islands only used the root. This chemical is apparently toxic to liver cells whereas kava lactones found in the root are not. 

Until we know the full details, it is best to restrict the use of kava to no more than a few days a month. Those with any kind of liver disease should not take kava, nor those who are taking medicines or have a chronic medical condition, unless they are supervised by a health care professional. The interaction of kava with pharmaceutical medicines or other supplements has not been tested. Caution is advised when mixing kava with other medicines, alcohol, or drugs.

   
Even if it is eventually found that regular, long-term kava use was responsible for the liver damage in these few individuals, we must keep things in perspective. There are thousands of deaths and hospitalizations each year from the use of aspirin and acetaminophen (Tylenol), yet they are available without a prescription and we don't hear sensational stories in the news about these fatalities. Overdoses of acetaminophen, the active ingredient in and other over-the-counter pain and fever relievers, is now the leading cause of acute liver failure in the US.

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