Several studies suggest that high fruit and vegetable intake reduces risk for stroke. To assess this relation further, researchers conducted a meta-analysis of nine prospective cohort studies involving more than 250,000 subjects, with a median follow-up of 13 years. All studies included adjustment for potential confounding variables. Subjects were stratified into three categories of fruit and vegetable intake: low (<3 servings daily), medium (3–5 servings daily), and high (>5 servings daily).
Both the medium- and high-intake groups were significantly less likely to develop stroke than the low-intake group (relative risks, 0.89 and 0.74, respectively). Differences in risk between the high- and low-intake groups remained significant regardless of sex, duration of follow-up, method of dietary assessment, and stroke subtype, whereas differences between the medium- and low-intake groups lost significance in some of these subgroups. Fruits and vegetables were both protective in the high-intake group, but only fruits were protective in the medium-intake group.
The difference between high and low intake of fruits and vegetables in this analysis is similar to the difference between recommended and actual intake in most developed countries, suggesting that widespread adherence to dietary recommendations might reduce the population burden of stroke substantially. A randomized trial in which subjects substantially increased their fruit and vegetable intake, compared with intake among controls, would be more persuasive than the observational studies analyzed here.
Reference:
He FJ et al. Fruit and vegetable consumption and stroke: Meta-analysis of cohort studies. Lancet 2006 Jan 28; 367:320-6.