FOR RELEASE:4 p.m. ET, MondayFebruary 12, 2001
CONTACT:For journal copies only,please call: (214) 706-1396For other information, call:Bridgette McNeill: (214) 706-1135 [email protected]Darcy Spitz: (212) 878-5940
American Heart Association journal report: Risk of rare stroke highest in women with lowest saturated fat intake, study finds
DALLAS, Feb. 13 ¥ A diet low in saturated fat was associated with an increased risk for a type of hemorrhage-induced stroke in women with high blood pressure, researchers report in today¥s Circulation: Journal of the American Heart Association.
"Given how much fat we eat in the United States, this study does not change our general goal of reducing the intake of saturated fat," says Meir J. Stampfer, M.D., a co-author of the report and a professor of epidemiology and nutrition at the Harvard School of Public Health.
"However, for people with high blood pressure, the goal should not be an extremely low-fat diet," Stampfer adds. "A more moderate approach may be sufficient to get the benefit for coronary disease without incurring the risk for hemorrhagic stroke."
The American Heart Association also stresses that individuals should not change their dietary habits based on a single study.
"This should not discourage people from following a diet that is low in saturated fat," says Alice H. Lichtenstein, D.Sc., a member of the American Heart Association's Nutrition Committee. "There is a large body of evidence showing that low saturated fat diets can dramatically reduce the risk of heart disease. This study deals with a specific population of women -- those with high blood pressure -- and one of the rarest forms of stroke in relation to diet."
Stampfer and his colleagues analyzed data from the long-term Nurses' Health Study that began in 1980. At the beginning of the study, 85,764 women, ages 34 to 59, completed dietary questionnaires. All of the participants were free of known heart disease and cancer. From the questionnaires, researchers calculated each woman¥s fat and protein consumption.
By 1996 the women had suffered a total of 690 strokes, including 74 (10.7 percent) intraparenchymal hemorrhages, one type of hemorrhagic stroke. Hemorrhagic strokes occur when a small or medium blood vessel inside the brain leaks or bursts. Most strokes are ischemic strokes, which result from the blockage of an artery carrying blood to the brain. Intraparenchymal hemorrhage is one of the less common forms of a hemorrhagic stroke.
The researchers divided the women into five groups, or quintiles, ranked from the lowest to highest for consumption of each of several types of fat, protein as well as stroke risk factors.
After taking into account the women's ages and smoking habits, the team found that women in the lowest quintile of saturated fat consumption -- eating about 20 grams of saturated fat a day -- had about double the risk of hemorrhagic stroke as women eating moderate amounts (between 25 and 36 grams per day).
The increased stroke risk observed in the group that consumed the least amount of saturated fat occurred primarily among women with high blood pressure.
"We know that hypertension is a key risk factor for hemorrhagic stroke," Stampfer says. "Our thinking is that individuals with a very low intake of saturated fat may develop some kind of structural impairment of the arteries, and this makes them more vulnerable to stroke if they have high blood pressure."
The amount of dietary cholesterol, polyunsaturated fat, and total fat consumed did not significantly increase the risk of this type of stroke.
The researchers found no increased risk associated with fat intake for blockage-induced (ischemic) strokes or for subarachnoid hemorrhage, a type of stroke in which the bleeding occurs on the surface of the brain. They did report, however, a modest trend toward a lower risk of intraparenchymal hemorrhagic stroke with increased monounsaturated fat consumption.
The researchers note that people who are vegetarians by choice, not poverty, eat a low-fat diet, yet have a low incidence of stroke in general. They speculate that the fruit- and vegetable-rich diet might help lower blood pressure and reduce the risk of stroke.
Although the study participants were all women, Stampfer says the findings are likely to apply to men as well.
The impetus for the stroke study was the finding that in rural Japan, where people eat very little animal fat, the incidence of hemorrhagic stroke is twice that of urban Japan. Stampfer and his colleagues say the new findings may help to explain the high rate of this type of stroke in Asian countries.
Co-authors include Hiroyasu Iso, M.D.; JoAnn E. Manson, M.D.; Kathryn Rexrode, M.D.; Frank B. Hu, M.D.; Charles H. Hennekens, M.D.; Graham A. Colditz, M.B.B.S.; Frank E. Speizer, M.D.; and Walter C. Willett, M.D.
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NR01-1248 (Circ/Stampfer)
Media Advisory: Dr. Stampfer can be reached by phone at (617) 432-6477 and by e-mail at [email protected]. Dr. Lichtenstein can be reached at (617) 556-3127. (Please do not publish contact information.)
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