A couple of heart-friendly dark brews - dark beers Guinness Extra stout and Heineken lager may reduce risk of heart disease - Brief Article

Science News, May 4, 1996 by Janet Raloff

Alcohol consumption can reduce heart disease risk, according to a variety of studies (SN: 3/30/96, p. 197). Will any type of alcohol do? Yes, but for persons with coronary artery disease, dark beer may be particularly effective.

People may get as much benefit from drinking two glasses of dark beer as from 12 servings of uncolored alcoholic drinks, a new study finds. But you're a teetotaler? No problem. Two cups of tea a day provide the same benefits-at least in dogs.

For years, John D. Folts of the University of Wisconsin-Madison has been testing the ability of various agents to reduce the stickiness of blood platelets. To mimic human atherosclerosis, he uses dogs whose coronary arteries have been artificially damaged and constricted by 60 to 80 percent.

Under the influence of stress, cigarette smoking, or various diseases, platelets periodically become activated, turning sticky and forming clumps. At such times, they tend to lodge in narrowed vessels, posing a risk of heart attack or stroke.

Last year, Folts showed that red wine and red grape juice, both rich in pigmented antioxidants known as flavonoids, inhibited platelet activation, while flavonoid-shy white grape juice did not. Now, Folts and his colleagues have tested several other commonly consumed flavonoid-rich beverages.

In one study, they delivered Guinness Extra stout, a dark, malty brew, directly into the stomachs of 11 animals. Another 5 received Heineken lager, a light-colored beer possessing fewer flavonoids. Chemically induced platelet clogs disappeared in all animals given dark beer and did not recur, even when the dogs were again challenged with a platelet-activating compound. Platelet clogs persisted in dogs receiving the lager but fell from an initial average of about seven per dog to roughly four.

In a companion study, the equivalent of two cups of tea eliminated platelet clogs in dogs as efficiently as dark beer did. This result supports studies that have linked reduced heart attack rates in humans to tea drinking (SN: 10/30/93, p. 278). Coffee appeared to aggravate clogging in Folts' canine study.

Other studies by the group suggest that flavonoids may bind to circulating platelets, eventually making a given amount more effective. Indeed, Folts points out, after 7 days of tea consumption, only half as much is needed to prevent platelet blockages.