There is emerging evidence that behavioral modification can modify your risk of stroke. Although it seems intuitive that a healthy lifestyle, with a balanced diet and exercise, would reduce stroke risk, the effects of these interventions are difficult to quantify. However, recently the evidence has begun to mount about the success of healthy diets reduces risk of stroke. Hu et al. explore this important question with a meta-analysis about fruit and vegetable consumption and the risk of stroke. In this paper, twenty prospective cohort studies were included which used fruit and vegetable consumption as the exposure, and risk of stroke as the outcome.
The authors found that the highest versus the lowest level of fruit and vegetable consumption was associated with more than a 20% reduction in the risk of stroke. To account for publication bias, they excluded 3 studies that reported a small effect size, with no difference in the result. They suggest that increase fruit and vegetable consumption may reduce blood pressure and have a favorable effect on cardiovascular risk factors. They also point out that while cohort studies are associational, several of Hill’s criteria for causation are met. They implicate that the one criteria not met is the evidence for “experiment”, or randomizing participants to giving fruits and vegetables t vs. placebo to see if stroke is truly reduced. This last “experiment” is the challenge in diet research, as these studies are often difficult to conduct and measure adherence to dietary patterns. Often, the outcome, such as stroke, is not immediate, and these studies can be long a costly. The success of the recent PREDIMED trial, however, suggests that these dietary intervention trials can be done, and do provide helpful evidence for dietary interventions to reduce stroke risk.