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ORLANDO, Fla. - Like chocolate and wine, the darker the beer, the better it may be for your heart, according to a new study.
In a comparison of Guinness Stout, a dark beer, and Heineken, a light beer, the darker brew had substantially more anti-clotting activity, according to a University of Wisconsin-Madison scientist who presented his findings Tuesday at the American Heart Association annual meeting.
Guinness proved to be about twice as effective at preventing the blood platelets from clumping and forming the kind of clot that can cause a heart attack, according to the study's main author, John Folts, a professor of medicine and nutritional director of the University of Wisconsin Coronary Thrombosis Research and Vascular Biology Laboratory.
The beneficial effect comes from flavonoids in the beer. Flavonoids are anti-oxidant compounds that provide the dark color in many fruits and vegetables. There are hundreds of flavonoids in beer, Folts said.
Flavonoids also work to prevent the oxidation of cholesterol, which plays a role in causing atherosclerosis - known as hardening of the arteries. They also help arteries to dilate, which improves blood flow and blood pressure, he said.
Folts did his research in test tube studies and on eight dogs.
He said a person would have to reach a blood alcohol level of 0.06 in order to get the optimal anti-clotting effect. He said that for the typical person, that could be accomplished with two, 12-ounce bottles.
However, doctors warned that even though dark beer may have heart-healthy properties, it also has a downside that could negate any benefit: extra calories.
Dark chocolate and red wine have similar properties, but they also provide extra calories, and obesity is a risk factor for heart disease.
"The bottom line is obesity is a major problem," said Alice Lichtenstein, a professor of nutrition at Tufts University and vice chairman of the American Heart Association's nutrition committee. "People need to worry about energy balance."
She added that those foods may have a lot of potentially beneficial components, but it's not well known which ones are the most beneficial. Until the actual active compounds are identified, she said can't recommend one food or beverage over another.
"There is such a range of dark beer and wines," she said. "There is such variation in the composition. It may be that it's not all dark beer (that's beneficial)."
Variation in the beneficial components could be due to diverse factors ranging from storage conditions to growing conditions, she said.
However, Ronald Korthuis, a professor of physiology at the Louisiana State University Health Sciences Center, said Folts' research bolsters epidemiological studies suggesting that alcoholic beverages can reduce heart attacks.
"What is impressive about Dr. Folts' observations is that the flavonoids in dark beer produce anti-platelet effects that rival those of aspirin," Korthuis said.
By understanding how these beverages work, it may be possible to develop therapies that mimic alcohol's beneficial properties, "but do not produce the unwanted negative social and pathophysiological effects," he said.
Folts said his goal is to isolate those compounds and put them into a pill.
In the meantime, he has at least one more study in mind.
"We'd like to do a study and have people drink dark beer for two weeks and drink two weeks of light-colored beer," he said. "We haven't found anybody interested in funding that."
(c) 2003, Milwaukee Journal Sentinel. Distributed by Knight Ridder/Tribune News Service.