The study, conducted at the Harvard-affiliated McLean Hospital in Boston, is published in this month's edition of Alcoholism: Clinical and Experimental Research.
Researchers found that people given the kudzu vine in a pill form had 1.8 beers during a 90-minute session compared with 3.5 beers for those who were not.
The study doesn't explain the exact effect of the kudzu, however researchers believe the results suggest that it speeds alcohol's impact; the subjects needed fewer beers to feel drunk.
Lead researcher Scott Lukas speculates "that rapid infusion of alcohol is satisfying them and taking away their desire for more drinks. That's only a theory. It's the best we've got so far."
A 2003 study of the effect of kudzu on rats resulted in the rats drinking less while subjected to the vine. This study is the first to test kudzu effects on humans.
Lukas recruited 14 men and women in their 20s to sip beer and watch television from reclining chairs in a hospital room set up like an apartment.
The study revealed to Lukas taht the "individuals reported feeling a little more tipsy or lightheaded, but not enough to walk into walls or stumble and fall."
Kudzu doesn't have any effect on the urge to drink, but researchers hope it might allow heavy drinkers to cut back.
"That way they're a lot closer to being able to cut down completely," Lukas said.
