FASUPPEffect of Obesity and Folic Acid Supplementation on Gene-specific DNA Methylation in Women of Reproductive Age

This study will be conducted in two phases. An initial screening study will be performed to determine folate status, MTHFR677 genotype and body composition of potential participants of the intervention study. Both folate status and MTHFR677 genotype are known independent predictors of response to folic acid supplementation. Blood samples will be collected, after an overnight fast, for determination of serum folate concentration and for MTHFR677 genotyping. Body composition and 24-hr dietary recalls will also be conducted during the screening visit. The second phase is an eight week supplementation trial with 800 mcg/day folic acid. Screened individuals determined to have a serum folate < 30 nmol/L (< 50th percentile of NHANES 1999-2004) and of the CC or CT genotype (for MTHFR677) will be eligible for inclusion in the supplementation trial. Participants will be instructed to avoid dietary supplements, fortified ready-to-eat cereals, and other high folate content foods during intervention. Blood samples will be collected, after an overnight fast, at baseline and after 4 and 8 weeks of supplementation for determination of primary (DNA methylation profile) and secondary (nutritional, metabolic and health status biomarkers) outcome measures.