Measures of adiposity and body fat distribution in relation to serum folate levels in postmenopausal women in a feeding study

Objective: To assess the associations between serum folate concentration and measures of adiposity in postmenopausal women. Design: This study was conducted as a cross-sectional analysis within the control segment of a randomized, crossover trial in which postmenopausal women (n=51) consumed 0g (control), 15 g (one drink) and 30g (two drinks) alcohol (ethanol)/day for 8 weeks as part of a controlled diet. Subjects in one treatment arm were crossed-over to another arm after a 2- to 5-week washout period. Body mass index (BMI) was measured, and dual energy X-ray absorptiometry (DEXA) scan administered to the women during the control (0g alcohol) treatment, and a blood sample from this group was collected at baseline and week 8 of each diet period and analyzed for folate, B12, homocysteine and methylmalonic acid. Setting: This study was conducted at the Beltsville Human Nutrition Research Center, MD, USA. Results: In multivariate analysis, women who were overweight had a 12% lower, and obese women had a 22% lower serum folate concentrations compared to normal weight women (P-trend=0.02). Vitamin B12 also decreased with increasing BMI (P-trend=0.08). Increased BMI, percent body fat, and absolute amounts of central and peripheral fat were all significantly associated with decreased serum folate, but were unrelated to serum B12, homocysteine or methylmalonic acid. Conclusions: Our data show that adiposity is associated with lower serum folate levels in postmenopausal women. With obesity at epidemic proportions, these data, if confirmed by prospective or randomized controlled studies, have important public health implications.