Dietary intake of the antioxidant vitamin C may be associated with reduced risk for stroke, especially in people who smoke, report Dutch scientists in a new study.
Using data from the Rotterdam study, a team from the Erasmus Medical Center in the Netherlands and the University of Debrecen, Hungary, investigated the link between antioxidant intake from food and risk of stroke. The people with the lowest amounts of vitamin C in their diets were 30 per cent more likely to have a stroke than people in the highest intake group (more than 133 milligrams daily), according to the study published in the latest issue of Neurology.
Antioxidants such as vitamin C are thought to fight oxidative stress, which plays a role in a number of diseases, including stroke. There has been significant research into the theory that antioxidants could help prevent progression of heart disease and its outcomes.
The study followed 5,197 people aged 55 and older living in Rotterdam, without cognitive problems and previous stroke. During an average of 6.4 years follow-up, 227 people suffered strokes.
Smokers with diets high in vitamin C were more than 70 per cent less likely to have a stroke than smokers with diets low in vitamin C (less than 95 milligrams per day).
The study also found smokers benefited from high levels of vitamin E in their diets. They were more than 20 per cent less likely to have a stroke than those with diets low in vitamin E. However similar effects of vitamin E were not seen in non-smokers.
Dietary supplements containing vitamins C and E and other antioxidants did not show added benefit in the study, although the investigators said this finding does not mean supplements have no potential benefit. The Recommended Daily Allowance of vitamin C in the US is 75 mg daily.
"These results agree with the view that high dietary intake of antioxidants, in particular vitamin C and - in smokers - vitamin E, reduces the risk of stroke," concluded the researchers.
A Finnish study in 2002 also found a relationship between low vitamin C levels and an increased risk of stroke, especially in overweight and hypertensive men. Another study by Korean researchers published in this month's Journal of the American College of Nutrition showed that higher intake of vitamin C is associated with the decreased risk of stroke in a population with a high prevalence of smoking.
It is thought that vitamin C enhances endothelial function, which inhibits artery clogging and lowers blood pressure. But some believe that people who take vitamin supplements or eat vitamin-rich fruits and vegetables are simply more health-conscious and therefore less likely to experience stroke.
Nevertheless researchers continue to investigate whether vitamins can prevent heart disease. A study published in July found that women who take vitamin C supplements may have a lower risk of developing coronary heart disease than women with low intakes of vitamin C.