A recent study by Harvard-affiliated researchers revealed that kudzu—an herb found to reduce alcohol consumption—does not work by increasing the intoxicating effects of alcohol so that individuals get drunk faster.

While the mechanism by which the plant extract lowers alcohol intake is still unclear, eliminating this particular explanation was crucial before the researchers could give drug companies the green light to produce new kudzu pills, which is expected to be marketed in the coming months.

“Essentially we know a little bit more about how kudzu doesn’t work at the moment,” said study co-author David M. Penetar, assistant professor of psychology in Harvard Medical School’s Psychiatry Department and a research psychologist at McLean Hospital. McLean Hospital is an affiliate of Harvard Medical School.

The kudzu vine, imported from Japan in 1876, has been written about in Chinese medical literature for centuries for its general health benefits. But recently, it has been tested for its ability to reduce alcohol cravings.

In 2005, researchers including Penetar and Director of McLean Hospital’s Neuroimaging Center Scott E. Lukas performed a study in which volunteers were given either kudzu or placebo pills for a week and then encouraged to consume as much beer as they desired in a relaxed setting—a laboratory complete with a sofa, television, and beer-stocked fridge. Compared to weeks in which the participants took no pill or a placebo, individuals with kudzu in their system consumed almost half as much alcohol—and showed no side effects or awareness of the drug.

But before Penetar and Lukas­—a Professor of Psychiatry at HMS—could endorse kudzu, they needed to be sure that it did not simply make individuals experience the same level of intoxication with half as much alcohol. If that were the case, taking the drug would help people get drunk faster rather than helping them drink less.

In this recent study, the researchers gave twelve participants different schedules of placebo or kudzu pills, and then observed the effects of drinking a set amount of vodka. They tested steadiness of gait, body sway, how well participants could stand upright, and how drunk they said they felt, among other factors. The researchers found that these types of responses were not intensified if participants had taken kudzu, suggesting that the drug does not work by increasing the intensity or duration of alcohol’s effects.

“You want to make sure that your medication is not as bad or worse than the drug you’re trying to treat,” Lukas said.

“I think that’s what’s kind of unique about this strategy of looking for alternative and complementary medicine,” he added. “The fundamental premise is that these are not very strong medicines with powerful side effects.”

The researchers next plan to use Magnetic Resonance Imaging to examine the effects of kudzu on how quickly alcohol gets into the brain.

They are also interested in the possibility of developing a dosage of kudzu that individuals could take once, before a night of drinking, rather than a set of pills which must be taken regularly.

Howard J. Shaffer, associate professor of psychiatry at HMS and Director of the Cambridge Health Alliance’s Division on Addictions, said that kudzu could be one among many effective treatments.

“I think it’s very important to look at a whole portfolio of resources—drugs and behavior, therapeutic approaches, cognitive treatments,” he said. “What we’re finding is that a cocktail of treatment approaches works better than any single treatment strategy.”

—Staff writer Julie R. Barzilay can be reached at jbarzilay13@college.harvard.edu.