Dietary and genetic determinants of homocysteine levels among Mexican women of reproductive age

Abstract

Objective: To evaluate the independent and joint effects of dietary folate, vitamin B12 consumption and methylenetetrahydrofolate reductase (MTHFR) polymorphisms (677C>62;T and 1298A>C) on the circulating folate and homocysteine (Hcy) levels among Mexican women of reproductive age. Design: A cross-sectional, population-based study. Subjects: The first 130 healthy non-pregnant women (aged 16-34 years) who agreed to participate in a reproductive cohort in Morelos, Mexico. Main outcome measurements: Dietary intakes of vitamin B12 and folate were estimated using a semiquantitative food frequency questionnaire. MTHFR 677C>T and 1298A>C polymorphisms were ascertained using the PCR-based method. Serum levels of Hcy and folate were determined using high-performance liquid chromatography and radioimmunoassay, respectively. Results: Genotype frequencies for the MTHFR 677C>T polymorphism were 21.5% (CC), 52.3% (CT) and 26.2% (TT) among Mexican women. Of the population, 22% had the MTHFR 1298AC genotype, while no individual carried the 1298CC genotype. We observed an increased level of Hcy among carriers of the 677TT genotype, compared to carriers of the 677CC genotype. The highest level of Hcy was observed among MTHFR 677TT carriers with low B12 intake (<2.0 μg/day), which resulted with a significant interaction (P=0.01). Conclusion: Vitamin B12 is an important determinant of Hcy levels in Mexico. Supplementation of folic acid with vitamin B12 may be preferable when the MTHFR 677T variant allele is prevalent. © 2006 Nature Publishing Group All rights reserved.