Low vitamin C concentration in the blood stream may be a risk factor for stroke, especially among hypertensive and overweight men, Finnish researchers report in the June issue of Stroke: Journal of the American Heart Association.

Men with blood vitamin C levels in the lowest quarter [less than 28.4 micromoles per liter (umol/L)] had a 2.1 times higher risk of any type of stroke compared with men in the highest quarter (more than 64.96 umol/L). The likelihood was higher for men who also had hypertension or were overweight.

There is a moderate correlation between vitamin C intake and the amount of vitamin C circulating in the blood, says lead researcher Sudhir Kurl, M.D. The lowest quartile in this study had an intake roughly equivalent to the vitamin C in half a glass of orange juice a day.

A possible effect of vitamin C is that it enhances endothelial function, which inhibits artery clogging and lowers blood pressure. However, the link could simply be that people who take vitamin supplements or eat vitamin-rich fruits and vegetables may be more health-conscious than those who don’t. So vitamin C alone may not be responsible for the results of the study, he says.

The research was compiled from a prospective follow-up study of 2,419 Finnish men between the ages of 42 and 60 and was funded in part by the National Heart, Lung and Blood Institute.