Study supports link between more fish and fewer strokes

Women who eat fish more than 3 times a week are less likely to suffer a stroke than women who eat fish less often than once a week, Scandinavian researchers report.

The researchers followed 34,670 Swedish women between 49 and 83 years of age for 10 years. None of the women had cancer or cardiovascular disease at the beginning of the study. During the follow-up period, 1,680 (4%) of the women had a stroke, most often an ischemic stroke (78%). Women who ate more than 3 servings of fish a week were 16% less likely to suffer a stroke than women who ate fish less often than once a week. The study was published online December 29 in The Journal of Clinical Nutrition.

Nutrients such as fatty acids and vitamin D might explain the benefits of eating fish, suggest lead author Suzanna Larsson of the Karolinska Institute, Stockholm, and her colleagues. “Fatty acids may reduce the risk of stroke by reducing blood pressure and blood (fat) concentrations,” Larsson writes. The study supports previous research showing an association between higher fish consumption and lower risk of stroke but doesn’t necessarily prove cause and effect because a healthier lifestyle among fish eaters or some other mechanism may be at work.

Women in this study seemed to benefit most from eating lean fish, whereas other research shows fatty fish to be more beneficial. The explanation may be that most fatty fish, such as herring and salmon, is eaten salted in Sweden and high salt intake increases blood pressure and, consequently, stroke risk. The study authors posit that the protective effects of fatty acids in fatty fish may be attenuated because of the salt.

Because the researchers asked women about their diets only once in a questionnaire, errors may have crept into the study that would underestimate the connection between a diet rich in fish and the risk of stroke. As a result, the actual decrease in risk may be larger than reported.