单项选择题

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Moderate drinking reduces stroke risk, study confirms. Similar to the way a drink or two a day protects against heart attacks, moderate alcohol consumption wards off strokes, a new study found.
The study also found that the type of alcohol consumed -- beer, wine or liqour -- was unimportant. Any of them, or a combination, was protective, researchers reported in today’s Journal of the American Medical Association. "No study has shown benefit in recommending alcohol consumption to those who do not drink", cautioned the authors, led by Dr. Ralph L. Sacco of Columbia University College of Physicians and Surgeons in New York. But the new data support the guidelines of the National Stroke Association, which say moderate drinkers may protect themselves from strokes by continuing to consume alcohol, the authors said.
The protective effect of moderate drinking against heart attacks is well established, but the data has been conflicting about alcohol and strokes, the authors said. The new study helps settle the question and is the first to find blacks and Hispanics benefit as well as whites, according to the authors. Further research is needed among other groups, such as Asian, whom past studies suggest may get no stroke protection from alcohol or may even be put at greater risk.
Among groups where the protective effect exists, its mechanism appears to differ from the protective effect against heart attacks, which occurs through boosts in levels of so-called "good" cholesterol, the authors said. They speculated alcohol may protect against stroke by acting on some other blood trait, such as the tendency of blood platelets to clump, which is key in forming the blood trait, such as the tendency of blood platelets to clump, which is key in forming the blood clots that can cause strikes.
The researchers studied 677 New York residents who lived in the northern part of Manhattan and had strokes between July 1,1993, and June, 1997. After taking into account differences in other factors that could affect stroke risk, such as high blood pressure, the researchers estimated that subjects who consumed up to two alcoholic drinks daily were only half as likely to have suffered clot-type strokes as nondrinkers. Clot-type strokes account for 80 percent of all strokes, a leading cause of US deaths and disability. Stroke risk increased with heavier drinking. At seven drinks per day, risk was almost triple that of moderate drinkers.
An expert spokesman for the American Heart Association, who was not involved in the study, said it was well-done and important information. But it shouldn’t be interpreted to mean, "I can have two drinks and therefore not worry about my high blood pressure or worry about my cholesterol," said Dr. Edgar J. Kenton, an associate professor of clinical neurology at Thomas Jefferson University Medical College in Philadelphia. Instead, he said, the study provides good reason to do further research and to add alcohol to the list of modifiable risk factors for stroke.
From the fourth paragraph we learn that ______.