Serum folate and risk for ischemic stroke. First National Health and Nutrition Examination Survey epidemiologic follow-up study.
OBJECTIVE
A serum folate concentration < or = 9.2 nmol/L has been associated with elevated levels of plasma homocyst(e)ine. Elevated homocyst(e)ine levels have been associated with ischemic stroke in case-control studies; however, the results from prospective studies have been equivocal. We investigated whether a folate concentration < or = 9.2 nmol/L was associated with ischemic stroke in a national cohort.


METHODS
We used data from the First National Health and Nutrition Examination Survey Epidemiologic Follow-up Study (n = 2006). Cox proportional hazards analyses were used to adjust for differences in follow-up time and covariates. During the 13-year follow-up, 98 ischemic strokes occurred.


RESULTS
After adjusting for age, race, sex, education, diabetes, history of heart disease, systolic blood pressure, body mass index, hemoglobin level, cigarette smoking, and alcohol intake, participants with a folate concentration < or = 9.2 nmol/L were at slightly increased risk for ischemic stroke (relative risk [RR], 1.37; 95% confidence interval [CI], 0.82 to 2.29). There was a folate-race interaction (P = .11 for interaction term). Whites with a folate concentration < or = 9.2 nmol/L had a relative risk of 1.18 (95% CI, 0.67 to 2.08), whereas blacks had a relative risk of 3.60 (95% CI, 1.02 to 12.71).


CONCLUSIONS
These findings suggest that a folate concentration < or = 9.2 nmol/L may be a risk factor for ischemic stroke, especially in blacks. However, given the small number of stroke events, additional studies are needed to assess the role of folate in the epidemiology of ischemic stroke.
Giles
W H
WH
Cardiovascular Health Studies Branch, Centers for Disease Control and Prevention, Atlanta 30341-3724, USA.
Kittner
S J
SJ
Anda
R F
RF
Croft
J B
JB
Casper
M L
ML
D000328:Adult; D000367:Age Factors; D000428:Alcohol Drinking / Q000453:epidemiology; D044383:Black People; D002545:Brain Ischemia / Q000097:blood / Q000453:epidemiology*; D002561:Cerebrovascular Disorders / Q000097:blood / Q000453:epidemiology*; D015331:Cohort Studies; D003920:Diabetes Mellitus / Q000453:epidemiology; D004522:Educational Status; D004812:Epidemiologic Methods; D005260:Female; D005492:Folic Acid / Q000097:blood*; D005500:Follow-Up Studies; D006331:Heart Diseases / Q000453:epidemiology; D006710:Homocysteine / Q000097:blood; D006801:Humans; D006973:Hypertension / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D012307:Risk Factors; D012737:Sex Factors; D012907:Smoking / Q000453:epidemiology; D044465:White People
D006710:Homocysteine; D005492:Folic Acid