'Western' Diets May Be Linked To Greater Stroke Risk

A "prudent" diet characterized by higher intakes of fruits, vegetables, fish, legumes and whole grains – like the one the American Heart Association recommends – may protect against stroke, the study found. This is the first study to examine overall dietary habits and stroke risk.

"Several foods and nutrients have been linked to the risk of stroke; therefore, dietary modification may be an important way to reduce the risk of stroke," said Teresa Fung, Sc.D., the study's lead author and assistant professor of nutrition at Simmons College School for Health Studies in Boston, and adjunct assistant professor of nutrition at the Harvard School of Public Health. "Because nutrients and food are consumed in combination, their cumulative effect on disease risk may be best investigated by considering the entire eating pattern."

Researchers gathered dietary information on 71,768 female nurses, ages 38-63, who had no history of heart disease or diabetes. Starting in 1984 and following them until 1998, researchers identified two dietary patterns: "prudent" and "Western."

The women reported their health, lifestyle, and diet information to the Harvard School of Public Health every two to four years. Researchers examined whether their diet affected subsequent stroke risk.

During 14 years of follow-up, 791 strokes occurred: 476 ischemic (caused by a blocked artery in the brain), 189 hemorrhagic (caused by a blood vessel rupturing on or near the brain) and 126 unclassified strokes.

Based on what they were eating, each nurse received two scores. The "prudent" score reflected how closely their diet resembled the prudent dietary pattern and the "Western" score reflected how closely their diet resembled the Western pattern. A higher score indicated closer adherence to the dietary pattern. The women were ranked according to the scores, then divided into five groups (quintiles). Because each participant received a Western diet and a prudent diet score, there was one group of quintiles for each type of diet. Those who were at the bottom quintile of each dietary pattern became the reference group, and all the other quintiles were compared against them, Fung said.

Researchers observed a higher relative risk for stroke among those consuming a Western diet. After controlling for lifestyle and risk factors for stroke, the risk for any type of stroke among women with the highest Western diet scores was 58 percent greater than the risk for women in the lowest quintile. The increased risk for ischemic stroke was about 56 percent greater.

While the results show that risk of any stroke for women with the highest prudent diet score was 22 percent lower than women with the lowest prudent diet score, these results were not statistically significant.

Women with Western eating habits were more likely to smoke, less likely to take vitamins and less active, the study found.

Women who ate the Western diet and also had hypertension had more than three times the risk of strokes caused by blockages compared with Western dieters without hypertension.

"Overall dietary patterns are easier to recommend to the public than individual foods," Fung said.

Although no men were included in the study, Fung said the results have applications for men's diets as well.

"I'd like to see people examine different components of their diets and make positive changes accordingly," she said.

More diet studies using food patterns may determine if this is the most effective way to identify disease risk.

Co-authors are Meir J. Stampfer, M.D., DPH; JoAnn E. Manson, M.D., DPH.; Kathryn M. Rexrode, M.D.; Walter C. Willett, M.D., DPH.; and Frank B. Hu, M.D., Ph.D.