“Eating antioxidant-rich foods may reduce your risk of stroke by inhibiting oxidative stress and inflammation,” says Susanne Rautiainen, a doctoral student at the Institute of Environmental Medicine, Karolinska Institutet, and first author of the current study. “This means people should eat more foods such as fruits and vegetables that contribute to total antioxidant capacity.”
Oxidative stress is an imbalance between the production of cell-damaging free radicals and the body’s ability to neutralize them. It leads to inflammation, blood vessel damage and stiffening. Antioxidants such as vitamins C and E, carotenoids and flavonoids can inhibit oxidative stress and inflammation by scavenging the free radicals. Antioxidants, especially flavonoids, may also help improve endothelial function and reduce blood clotting, blood pressure and inflammation.
For the study, the researchers used the Swedish Mammography Cohort to identify 31,035 heart disease-free women and 5,680 women with a history of heart disease in two counties. The women were 49-83 years old. Researchers also identified 1,322 strokes among cardiovascular disease-free women and 1,007 strokes among women with a history of cardiovascular disease from the Swedish Hospital Discharge Registry.
Dietary data where then collected through a food-frequency questionnaire. The researchers used a standard database to determine participants’ total antioxidant capacity (TAC), which measures the free radical reducing capacity of all antioxidants in the diet and considers synergistic effects between substances. The researchers then categorized the women according to their TAC levels – five groups without cardiovascular disease and four with previous cardiovascular disease.
For women in the highest quintile, fruits and vegetables contributed about 50 percent of TAC. Other contributors were whole grains (18 percent), tea (16 percent) and chocolate (5 percent).
The study found that women without cardiovascular disease in the highest quintile of dietary TAC had a statistically significant 17 percent lower risk of total stroke compared to those in the lowest quintile. Further, that women with history of cardiovascular disease in the highest three quartiles of dietary TAC had a statistically significant 46 percent to 57 percent lower risk of hemorrhagic stroke compared with those in the lowest quintile.
“Women with a high antioxidant intake may be more health conscious and have the sort of healthy behaviors that may have influenced our results,” says Susanne Rautiainen. “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.”