PHILADELPHIA — Kudzu, often reviled as "the vine that ate the South," apparently brings something else to the table: a promising treatment for binge drinkers.

Researchers at Harvard-affiliated McLean Hospital outside Boston report that heavy drinkers who took a concentrated extract of kudzu root for one week downed a lot less beer: two or three brews in 1 ½ hours instead of their usual five or six.

"That's a pretty powerful response," said Scott Lukas, director of the hospital's drug-abuse research lab and lead author of the study, which appeared in this month's issue of Alcoholism: Clinical and Experimental Research.

Earlier kudzu studies have shown reduced consumption among alcohol-swilling monkeys, rats and hamsters. And while Lukas' study is small and preliminary, it is the first to conclude what the Chinese have maintained for centuries: that compounds in the ancient vine, also known as ge-gen, can help problem drinkers imbibe less.

Researchers aren't sure how it works, but Lukas suspects that active ingredients called isoflavones in the kudzu root increase blood flow, which helps alcohol get to the brain faster. This means drinkers "are getting cues that say, 'I'm feeling good, I'm OK, no need to suck down this entire beer,' " he said.

Binge drinkers don't usually pay attention to those cues. "They drink so darned fast, they don't have the opportunity to perceive the effects of the alcohol," Lukas said.

About 1 in 3 adult drinkers in the United States report binge drinking in the previous month. The Centers for Disease Control and Prevention defines binge drinking as five or more drinks at one sitting for men and four or more for women.

Lukas recruited 14 heavy drinkers — 11 men and three women, aged 21 to 32 — for his study. The study showed those who took kudzu drank an average of 1.8 beers per session compared with their original 3.5, while those on a placebo drank the same as before.

Unlike drug treatments for alcoholism, no side effects were reported from the kudzu. "Nothing," Lukas said. "We were stunned."

Kudzu was introduced to the United States in 1876. The federal government once promoted it for erosion control, paying farmers up to $8 an acre to fill their fields with it.

Perhaps too late, the hairy-stemmed vine with 8-inch leaves and mammoth roots was declared a noxious invader. In the South, kudzu has smothered millions of acres of forest and all else in its path, including bridges, buildings, signs, utility poles and cars.