Dietary intake of folate and risk of stroke in US men and women: NHANES I Epidemiologic Follow-up Study. National Health and Nutrition Examination Survey.

BACKGROUND AND PURPOSE Few population-based studies have examined the relationship between dietary intake of folate and risk of stroke and cardiovascular disease (CVD). This study examines the association between dietary intake of folate and the subsequent risk of stroke and CVD. METHODS Study participants included 9764 US men and women aged 25 to 74 years who participated in the National Health and Nutrition Examination Survey I Epidemiologic Follow-up Study (NHEFS) and were free of CVD at baseline. Dietary intake of folate was assessed at baseline using a 24-hour dietary recall and calculated using ESHA software. Incidence data for stroke and CVD were obtained from medical records and death certificates. RESULTS Over an average of 19 years of follow-up, 926 incident stroke events and 3758 incident CVD events were documented. The relative risk (RR) was 0.79 (95% confidence interval [CI], 0.63 to 0.99, P=0.03 for trend) for incident stroke events and 0.86 (95% CI: 0.78 to 0.95, P<0.001 for trend) for incident CVD events in the highest quartile of dietary folate intake (median, 405.0 microg/day) compared with those in the lowest quartile (median, 99.0 microg/day), after adjustment for established cardiovascular risk factors and dietary factors. CONCLUSIONS Our findings indicate an inverse relationship between dietary intake of folate and subsequent risk of stroke and CVD. Increasing dietary intake of folate from food sources may be an important approach to the prevention of CVD in the US population.