Diet Rich in Vitamin C Decreases Stroke Risk

Laurie Barclay, MD

November 10, 2003

Nov. 10, 2003 -- Vitamin C-containing foods are associated with reduced risk of stroke, according to the results of the Rotterdam Study published in the Nov. 11 issue of Neurology. The effect was most pronounced in smokers, and supplements did not have the same benefit in this study.

"Of course these study findings do not justify smoking. No one should smoke," senior author Monique Breteler, MD, PhD, from Erasmus Medical Center in Rotterdam, Netherlands, says in a news release. "But it is good news that high levels of antioxidants may help reduce the risk of stroke in smokers."

The 5,197 subjects in this observational study were aged 55 years or older, living independently in Rotterdam, with no cognitive problems and no previous stroke history. Dietary levels of vitamin C and other antioxidants were assessed with a checklist of all foods and drinks consumed at least twice a month during the past year, as well as with an interview by a dietician.

During an average follow-up of 6.4 years, 253 people had strokes, including 227 with ischemic stroke. After adjustment for potential confounders, participants in the lowest tertile of dietary vitamin C (less than 95 mg daily) were 34% more likely to have ischemic stroke than participants in the highest tertile (more than 133 mg daily). Among the smokers, diets high in vitamin C were associated with a 72% reduction in stroke risk compared with diets low in vitamin C.

Although smokers with diets high in vitamin E were 23% less likely to have a stroke than those with diets low in vitamin E, there was no similar protective advantage for nonsmokers.

Study limitations include those inherent in an observational design, notably the possibility of residual confounding.

The lack of protective effect of dietary supplements containing vitamins C and E and other antioxidants in this study does not mean that supplements have no potential benefit, according to Dr. Breteler. She attributed this finding to possible increased risk of stroke in people who take supplements, as well as differences in the use of supplements and dietary habits. Dietary intake typically reflects long-term habits, while supplement use is generally shorter term and higher dose.

"Supplement use and diet are different types of intake of antioxidants, and they may have different effects on cardiovascular disease," the authors write. "Our finding that high dietary intake of antioxidants but not supplement use is associated with a reduced risk of stroke should not be misinterpreted as evidence against a potential beneficial effect of vitamin supplements."

The Netherlands Organization for Scientific Research, the Netherlands Health and Development Research Council, and the city of Rotterdam supported this study. The Hungary Ministry of Health, the Netherlands Institute for Health Sciences, and Erasmus University supported one of the study coauthors.

Neurology. 2003;61:1273-1275

Reviewed by Gary D. Vogin, MD



Comments on Medscape are moderated and should be professional in tone and on topic. You must declare any conflicts of interest related to your comments and responses. Please see our Commenting Guide for further information. We reserve the right to remove posts at our sole discretion.
Post as: