Evidence indicates that vitamin E appears to reduce the risk for atherosclerosis, and that it has an inverse association with risk for coronary heart disease, peripheral arterial disease and carotid artery wall thickness. These results might imply that risk for ischemic stroke may also be reduced by the intake of vitamin E, although the risk for hemorrhagic stroke might be increased because high doses of vitamin E cause reduced platelet adhesiveness. Vitamin C and carotenoids have antioxidant effects similar to those of vitamin E and might also be considered protective against stroke.
Ascherio and associates evaluated the relation of intake of vitamin E, vitamin C and specific carotenoids to the risks for ischemic and hemorrhagic stroke in a large group of men in the United States. Data from the Health Professionals Follow-up Study, initiated in 1986, in which information about diet, medical history and lifestyle were gathered longitudinally from over 51,529 men, was used to determine nutritional calculations and duration of vitamin E and vitamin C supplementation. Other potential risk factors for stroke were assessed at the time of the initial and follow-up questionnaires. End points were fatal or nonfatal strokes occurring over the eight-year follow-up period. Stroke caused by infection or neoplasm were excluded. During 323,394 person-years of follow-up, 210 ischemic strokes, 70 hemorrhagic strokes and 48 unclassified strokes were documented. Risk factor distribution for stroke differed by vitamin E, vitamin C and beta-carotene intake, requiring control for these variables in all multivariate analyses. For example, patients with higher intake of vitamin E or vitamin C were less likely to smoke and those with higher intake of beta-carotene and other carotenoids consumed more dietary fiber in the form of fruits and vegetables.
Despite the large range of vitamin E and vitamin C intake among the participants, neither vitamin was notably associated with reduction in risk for total, ischemic or hemorrhagic stroke. Lutein was the only carotenoid inversely related to stroke, but this might have been due to other dietary factors because higher lutein intake was associated with higher intake of potassium, folate and other nutrients. No notable associations were found between the dosage of supplements or the duration of supplement use and stroke of any type. Because the subjects in this study had healthier diets than average men and because men with cardiovascular disease were excluded from the study, the value of vitamin E, vitamin C or carotenoid supplementation in populations with deficient diets or with cardiovascular disease cannot be determined.
The authors conclude that the use of vitamin E or vitamin C supplements is unlikely to reduce stroke risk in adult men with no history of cardiovascular disease or diabetes. Although some carotenoids may reduce stroke risk, there is insufficient evidence to recommend an increased intake of specific supplements. Dietary prevention of stroke should include increased intake of fruit and vegetables as previous studies have suggested.