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Scott Lukas, professor of psychiatry at McLean, describes results of recent research: 'Those who took kudzu drank significantly less than those on placebo.' (Staff photo Justin Ide/Harvard News Office)

Kudzu cuts alcohol consumption

The weed that whacks binge drinking

By William J. Cromie
Harvard News Office

The vine that ate the South has a sobering effect on binge drinkers.

Researchers at McLean Hospital in Belmont, Mass., suspected that excessive drinking might be curbed by giving drinkers an extract of kudzu, a pesky, rapidly growing weed common in the Southern states. They knew it has been used for that purpose in China since 600 A.D. More recently, other researchers at Harvard University tested it on golden hamsters, bred and born to drink alcohol, and found that it reduced the rodents' intake.

kudzu drawing

"These results prompted us to test an herbal extract of it on humans," notes Scott Lukas, professor of psychiatry at McLean, a psychiatric hospital affiliated with Harvard Medical School. He and his colleagues recruited 14 men and women, average age 24 years. The "laboratory" was an apartment where each person was allowed to drink as many beers as he or she wanted, up to a maximum of six. After determining how much each person drinks normally, half were given a capsule of kudzu or an inactive pill or placebo.

After a so-called "washout" period, treatments were reversed. Those who had gotten the kudzu received a placebo and vice versa. Researchers who evaluated their drinking behavior did not know who received what or when.

The results were dramatic. "Those who took kudzu drank significantly less than those on placebo," says Lukas. "Everyone took that first drink when they came to the apartment after work. But the kudzu group was slower and less likely to reach for the second or third beer. They downed an average of one or two beers while the placebo group finished three or four. Alcohol consumption was almost cut in half."

Beyond that, those on kudzu drank more slowly. "They needed more gulps to finish each beer," Lukas continues. "That tells us they are responding to cues from their brains telling them they don't need to drink so much."

So in the first study of its kind, the much-maligned vine shows great potential for reducing bingeing, defined as putting down five or more drinks in one sitting for a man, or four or more consecutive drinks for a woman. Bingeing is a huge problem on most college campuses. A Harvard School of Public Health survey recently found that one-third to one-half of these students admit to binge drinking, thus contributing to alcohol being the third leading cause of death and disability in the United States.

Fewer hangovers

Another plus for kudzu is a lack of side effects. "We gave our subjects a low dose for one week," Lukas explains. "Then we gave them blood and urine tests and physical exams. No changes were found. It's a wonderful result. If we raised the dose and gave it for a longer period, alcohol consumption might be decreased even more. We expect to look into this possibility."

If people drink less, hangovers should be reduced in number and severity. "That's possible," Lukas agrees. "Drinking half the number of beers or drinks, say three or four instead of six or eight, should have a lesser effect the next day." But, he points out, there are no studies to demonstrate that kudzu would act like a morning-after pill for eliminating hangovers.

Does this mean that students and others who wish to reduce drinking and its miserable aftermath can medicate themselves safely with the widely available herb? No, Lukas' group tried that and it didn't work.

"We bought a variety of kudzu extracts from stores and Internet sites, tested them, and found that none of them worked, he says. "David Lee, a chemist on our research team did assays that showed these products contained less than 1 percent of active kudzu."

Lukas' group increased the concentration to 30-40 percent, and instructed their drinkers to take two of the pills three times a day. Commercial sellers of kudzu advise people to take many more doses a day. "These products also contain lots of protein and starch," Lukas notes. "They are as filling as a meal and so reduce your desire to drink as much alcohol as you might do normally."

How it works

The fast-growing plant was first brought to the United States from Japan in the 1920s as a way to hold down soil erosion. No one realized that kudzu would lack the kind of natural enemies that keep it in check in Asia - insects and climate. Its quickness to overgrow everything that doesn't move led people to call it "the vine that ate the South."

But how can an extract of it work to increase sobriety? The short answer is that no one knows. The McLean study was not designed to answer that question. The long answer is a theory that the herb can make alcohol go to your head faster.

In China, high concentrations of one of Kudzu's active ingredients (puerarin) are used medically to increase blood flow to the brain and heart, particularly in emergencies. "Wherever blood goes, alcohol goes," Lukas explains. "We think that this triggers a quicker response. The brain says 'enough' in less time. People feel satisfied on fewer beers.

"Kudzu is not going to take someone who drinks 30 beers a week and turn him or her into a teetotaler, but you might go from 30 to 15 a week. It's not a panacea or a magic bullet, but it looks like it could be a tool for people to reduce their drinking."

Copyright 2007 by the President and Fellows of Harvard College