First author, Susanne Rautiainen, said: "Eating antioxidant-rich foods may reduce your risk of stroke by inhibiting oxidative stress and inflammation. This means people should eat more foods such as fruits and vegetables that contribute to total antioxidant capacity."
Free radicals, oxidative stress and antioxidantsOxidative stress occurs when there is an imbalance between the production of free radicals, which damage cells, and the human body's ability to neutralize them or repair the subsequent damage, which results in blood vessel damage, stiffening and inflammation.
Oxidative stress can be inhibited by antioxidants, such as vitamins E and C, flavonoids, and carotenoids - antioxidants scavenge the free radicals. Flavonoids, for example, can help improve endothelial function, blood pressure, inflammation, and reduce blood clotting.
Rautiainen and team gathered data from the Swedish Mammography Cohort and identified 31,035 women who were free of cardiovascular disease and 5,680 others with a history of cardiovascular disease in two counties. They were aged from 49 to 83 years. Among the cardiovascular-disease free women they identified 1,322 cases of stroke, and 1,007 cases in the others.
With the use of a food-frequency questionnaire, they gathered data on the women's eating habits. They determined the women's TAC (total antioxidant capacity). TAC measures the free radical-reducing capacity of all antioxidants in the diet and takes into account the synergistic effects substances might have on each other. The women were then categorized according to their TAC levels - there were nine groups, five among those with no history of cardiovascular disease and four with a history of cardiovascular disease.
Fruit and vegetables contributed to about half the TAC for women in the highest quintile. Other key foods included whole grains at 18%, tea 16% and chocolate 5%.
Those in the highest quintile of dietary TAC had a 17% lower risk of developing stroke compared to those in the lowest quintile - the authors described this as a "statistically significant difference".
The risk of hemorrhagic stroke was from 46% to 57% lower among the women in the highest three quartiles of dietary TAC compared to those in the lowest quintile.
A diet high in fruit and vegetables can protect against stroke
"Women with a high antioxidant intake may be more health conscious and have the sort of healthy behaviors that may have influenced our results. However, the observed inverse association between dietary TAC and stroke persisted after adjustments for potential confounders related to healthy behavior such as smoking, physical activity and education."
Written by Christian Nordqvist