The average follow-up time was 9.5 years, and the final study included almost 200,000 person-years. During that time, 448 of the study participants had a stroke.
After compensating for other risk factors, such as gender, smoking history, body mass index, blood pressure, cholesterol levels, diabetes, alcohol consumption, physical activity and a history of heart disease, the researchers found that those with the highest levels of vitamin C in their blood had a 42 percent reduced risk of stroke compared to those with the lowest levels.
The difference between the vitamin C levels between the lowest and highest group roughly translates to about one extra fruit or vegetable daily, according to the study.
"The strong inverse association between plasma vitamin C and stroke suggests that plasma vitamin C is likely to be a good biomarker of whatever causal factors affect stroke risk, most plausibly the dietary intake of plant foods," the study's authors wrote.
"This study did not prove that vitamin C directly causes these benefits. It could be related to something else you do in your diet. We just don't know what the mechanism is that reduces stroke risk," said Siller, who added, "People should still go ahead with the American Dietetic Association recommendations to incorporate more fruits and vegetables into their diet. Don't rush to the store to buy vitamin C supplements."
"Many, many studies show a strong association between those who eat fruits and vegetables and a health benefit, and that benefit comes from eating foods, not supplements," Levine added.
To learn more about stroke prevention, visit the National Institute of Neurolog
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