UH scientists may have solved kava mystery
By Kevin Dayton
Advertiser Big Island Bureau
HILO, Hawai'i A team of University of Hawai'i scientists may have solved the mystery of why some Europeans who used products containing kava extract suffered severe liver damage, prompting a number of nations to ban sales of the herbal supplement.
Bruce Asato The Honolulu Advertiser
University of Hawai'i professor C.S. Tang, left, and his graduate assistant, Klaus Dragull, are researching kava.
Bruce Asato The Honolulu Advertiser
Just to be safe, people should avoid tea or anything else made from the leaves or stems of the plant, according to C.S. Tang, professor of molecular biosciences and biosystems engineering at UH-Manoa.
Bans in Singapore, Germany, Canada, the United Kingdom and elsewhere wiped out pharmaceutical sales of kava and virtually destroyed it as an export crop in Hawai'i. While kava supplements are not banned in the United States, the Food and Drug Administration issued an advisory in March 2002 warning of the potential risk of severe liver injury from dietary supplements containing kava.
The health alarms left farmers in Hamakua and elsewhere with crops that were hardly worth harvesting.
Experts were unable to explain how a plant used in island cultures for 2,000 years could suddenly be so toxic, causing liver damage that was fatal in some cases.
Now researchers led by Tang believe they may have found the key: Peelings from the stem bark of kava plants apparently were used to create the extract for the herbal supplements, and may be to blame for liver failure and liver-related injuries that included hepatitis and cirrhosis.
Traditional kava drinkers discard the peelings, but Tang and his team learned from a trader in Fijian kava that European pharmaceutical companies eagerly bought up the peelings when demand for kava extract soared in Europe in 2000 and 2001.
"Peelings are traditionally avoided by the kava drinkers with good reason," Tang said. "If you don't respect the traditional use or people who learn by experience, if you don't respect that, you might get yourself in trouble."
Supplements containing kava are promoted as remedies for sleeplessness and menopausal symptoms.
Drinking kava has not been associated with liver damage.
In Europe, where most of the health problems occurred, kava extract is used in capsule form, and the cases of liver damage apparently involved people who took the capsules, the scientists reported.
In a research paper accepted for publication in the scientific journal Phytochemistry, researchers Klaus Dragull, W.Y. Yoshida and Tang report they found an alkaloid called pipermethystine in tests of stem peelings and kava leaves.
Pipermethystine also was present in lower concentrations in the bark of the stump but was not found in the root itself. The root is what is used to make the traditional drink.
Preliminary tests by researcher Pratibha Nerurkar show pipermethystine has a "strong negative effect" on liver cell cultures. If peelings containing the alkaloid were used to make kava capsules and the scientists suspect they were that could explain the liver damage in some of the people who took the capsules.
The peelings were available during the kava boom because kava drinkers in the Pacific didn't want them, and the stem peelings contain high levels of kavalactones, the ingredient in kava that provides its calming effects.
The Fijian kava dealer reported the peelings had emerged as a very important trading item because "it's cheap and it's a waste product by the kava drinkers, therefore the pharmaceutical companies, they love it and it became part of the trade," Tang said.
The UH researchers also learned that the analysis method used by some companies to test plant products could not detect the difference between the alkaloids and kavalactones, "and therefore they mistakenly thought there's no problem, that it's similar stuff," Tang said.
"I'm fairly optimistic that we are on the right track, because everything seems to be falling into the picture because of the use of peelings," Tang said. "But like any scientist, I would say that nothing is final until our results are accepted by the regulatory agencies."
If the researchers are right, kava could again emerge as a viable export crop. But that could take quite awhile.
At its peak in 2001, the state Department of Agriculture estimates there were 65 farms in Hawai'i growing kava, but growers agreed that has dropped off dramatically.
Matthew Archibald, vice president of operations for Agrinom, an agricultural company in Hakalau on the Big Island, said the UH research is an important step in resuscitating the kava industry worldwide, but that it could take years and millions of dollars to rebuild the European market.
In August 2001, Agrinom was shipping 50,000 pounds of dried kava a month, grossing $300,000. That operation collapsed two months later when the German government banned sales.
"The damage has been done," he said. "For example, we're not going to get into Germany for a very, very long time. There would have to be some major development for us to be able to get back in there. But if someone could open up China, for example, where they're more accepting of herbal medicines in general, that could be a possibility."
Reach Kevin Dayton at firstname.lastname@example.org or (808) 935-3916.