By analyzing the dietary habits of a large population of Swedish women, researchers evaluated whether the total antioxidant capacity (TAC), a measurement of the ability of foods to decrease free radicals, plays a role in decreasing stroke risk (presumably by limiting inflammation and oxidative stress).

Nearly 37,000 women completed questionnaires on detailed accounts of their diets, including the types and frequency of foods consumed. Other important variables, such as smoking status, body mass index, physical activity, alcohol use, and history of certain diseases, were also recorded. The presence of cardiovascular disease (CVD), defined as a history of stroke, heart attack, angina, atrial fibrillation, or congestive heart failure, was ascertained from discharge information in a national hospital discharge registry.

"Total stroke," one of the primary end points, was the combination of all cerebral infarctions, hemorrhagic strokes, and unspecified strokes.

Within the group of 31,035 women who had no history of CVD, the mean follow-up time was 11.5 years, and 1,322 stroke episodes were identified. By organizing the data into quintiles (Q1 through Q5) of antioxidant consumption, the researchers compared women with the largest amount of TAC in their diet (Q5) with women with the lowest amount (Q1). Women in Q5 drank 17 times more tea than the women in Q1; ate twice the amount of fruits and vegetables; and more often were nonsmokers, took vitamins, and were better educated. An analysis that adjusted for multiple confounding variables found the risk of total stroke in Q5 women was 17% lower than that in Q1.

The average follow-up time in the 5,680 women who had CVD was 9.6 years; 1,007 stroke episodes were identified. The only statistically significant finding in this group was related to hemorrhagic stroke: women in the highest three quartiles (quartiles were used because of the smaller sample size) had a 46% to 57% lower risk of this type of stroke compared with those in Q1.

The researchers noted a significant inverse relationship between dietary TAC and both total stroke in women without a history of CVD and hemorrhagic stroke in women with CVD-supporting the notion of the important role that a diet high in antioxidants plays in stroke prevention.-AK

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