In August 2002 Health Canada issued a stop-sale order for kava (Piper methysticum) products in Canada. Citing a handful of reports of liver damage associated with prolonged kava use, the Canadian regulatory agency decided to remove all kava-containing products, including the raw herb, from the Canadian market.
To many the claim that kava causes liver damage does not square with the fact that kava has been in use for centuries as a traditional ceremonial beverage in the South Pacific Islands. The typical quantities consumed in the South Pacific far exceed normal doses of kava products sold in Canadian stores before the ban. If kava were damaging to the liver then it stands to reason to expect that evidence of liver damage would be widespread in the South Pacific were kava is consumed; but no evidence of unusual rates of liver damage where kava is traditionally used has surfaced.
Why kava products suddenly became suspect as a liver toxin is a matter of speculation. Some argue that the manufactured products are concentrated in a manner that differs greatly from the traditional practice. Commercial kava products are extracted using organic solvents such as benzene, while the traditional extraction involves a process of oral mastication and fermentation in water.
The aim of manufacturers is to maximize the kavalactones content in their products because kavalactones are presumed to be the active constituents in kava. But the use of a completely different solvent in the manufacture of kava products carries the risk that other active compounds besides kavalactones are either excluded or included, thereby changing the fundamental properties of the extract. Little is known about this effect and its possible role in reported cases of liver damage associated with kava use.
University of Hawaii researchers think that a substance found in stem peelings and leaves may be the culprit. The stem peelings and leaves contain an alkaloid called pipermethystine which is not found in the roots traditionally used in the Pacific. Tests show that pipermethystine causes a "strong negative effect" on liver cell cultures. According to an April 2003 report in The Honolulu Advertiser, stem peelings are a waste product normally discarded by users in the Pacific. However the peelings were found to contain high levels of kavalactones and pharmaceutical companies eagerly bought them from traders. But even if the UH researchers are right, it could take years and millions of dollars before kava is accepted as safe by the regulatory authorities.
Even with the use of manufactured kava products the risk of liver damage may actually be far less than that of other commonly ingested compounds. The Canadian Health Food Association (CHFA) has pointed out that acetaminophen, the widely consumed analgesic found in over-the-counter drugs such as Advil and Tylenol, is also damaging to the liver. As the CHFA says in its March 2003 release, there are over 200 deaths in the United States each year from acute liver failure associated with acetaminophen overdose. Yet, Health Canada has chosen only to issue an advisory on acetaminophen use, while its ban of kava is far more harsh. So far only a potential risk of liver damage has been associated with kava use, and although three deaths worldwide have been linked to kava use, those deaths were not proven to have been caused by kava.
The CHFA argues that any risk of kava use should be managed the same way that acetaminophen use is managed: by appropriate labelling so consumers can make an informed choice about the use of kava. The CHFA goes on to suggest that alcohol and even grapefruit are more damaging to the liver than kava may be; yet these products remain on the market. Because alcohol and grapefruit consumption is so widespread Health Canada’s ban is out of proportion to the greater overall risk that these products present to the public.
Health Canada’s ban of kava means that a valuable herb clinically proven to provide short-term relief from anxiety and depression is now unavailable to professional herbalists and to the public. Herbalists believe that, at the very least, the raw herb, unaltered by any manufacturing process, should be remain on the market.
Germany Lifts Kava Ban
Germany, one of the first countries to ban kava, has decided in May 2005 to lift its ban. According to Herbalgram, the German Federal Institute for Drugs and Medical Devices, acting on "persistant appeals" from kava producers, decided for "reasons of appropriateness" the ban was no longer warranted.
The repeal does not mean that kava products are free to be sold in Germany again; it only removes a categorical licensing ban on kava product registrations. Manufacturers still have to apply for new product registrations even if they had products previously registered before the ban. There is no assurance yet that the bar has been lowered enough to win approval.
The repeal of the ban is a very positive development in what Richters maintains is a grossly unfair treatment of a valuable medicinal herb. We are hopeful that other countries will follow the German lead, as they did when Germany first banned kava in 2002.
[Updated July 5, 2005]