Higher total homocysteine concentrations and lower folate concentrations in premenopausal black women than in premenopausal white women

Background: Premenopausal black women have a greater rate of coronary artery disease (CAD) than do premenopausal white women. Plasma total homocysteine concentrations, a risk factor for CAD, have not been reported in premenopausal black women. Objective: The purpose of this study was to compare plasma total homocysteine, folate, and vitamin B-12 concentrations in premenopausal black and white women. Design: Eighty-nine black and 90 white, healthy, premenopausal women living in Portland, OR, were recruited. Dietary histories were obtained by using the Diet Habit Survey, a 40-item eating-behavior questionnaire. Plasma concentrations of total homocysteine, folate, and vitamin B-12 were measured. Results: Black women had higher plasma total homocysteine (8.32 compared with 7.60 μmol/L; P = 0.013), lower plasma folate (6.62 compared with 9.88 nmol/L; P < 0.0001), and higher vitamin B-12 (355 compared with 283 pmol/L; P < 0.001) concentrations than white women. White women had a greater rate of daily multivitamin supplement use (42.4% compared with 24.7%; P = 0.019) and ate more ready-to-eat cereal than did black women. After adjustment for multivitamin use and intake of ready-to-eat cereal, plasma total homocysteine concentrations did not differ significantly, but plasma folate remained significantly lower in the black women. None of the black women but 12.3% of the white women (P = 0.013) were homozygous for the cytosine to thymidine mutation at nucleotide 677 in the methylenetetrahydrofolate reductase gene. Conclusions: Black women had higher plasma total homocysteine and lower plasma folate concentrations than white women, largely because of lifestyle factors, which may contribute to the greater rate of CAD in premenopausal black than in white women.