Background and purpose: Folate status was inversely associated with plasma homocysteine concentration, a potential risk factor of cardiovascular disease. However, it is uncertain whether folate is causally associated with risk of ischemic stroke (IS). We aimed to examine the association between IS incidence and folate intake, biochemical folate status, and folate associated nutrients.
Methods: Information on baseline characteristics and food frequency questionnaire was collected in 1990 to 1993 and included for analyses data from 1772 adults over 40 years, who were free of stroke and cancer at baseline from the CardioVascular Disease risk FACtor Two-township Study. Multivariate Cox proportional hazard model was used to relate baseline nutrient status with IS event.
Results: Over an average of 10.6 years of follow-up, 132 incident IS events were documented. Low folate intake (1st and 2nd quartiles) was significantly and independently associated with increased IS risk (HR=1.61; 95% CI: 1.04 to 2.48 and HR=1.82; 95% CI: 1.20 to 2.76) compared with those in the 3rd and 4th quartile combined, whereas no association was observed for plasma folate concentration. On the other hand, several nutrients correlated with dietary folate: vitamin B2, potassium, iron, vitamin A of plant origin, calcium were also associated with IS risk in an inverse linear manner with HR ranging from 1.5 to 1.9 for the first quartile.
Conclusions: The protective association of dietary folate on IS risk may be in part through that of other correlated nutrients or other dietary components.