title: 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 B(12) consumption and methylenetetrahydrofolate reductase (MTHFR) polymorphisms (677C>T and 1298A>C) on the circulating folate and homocysteine (Hcy) levels among Mexican women of reproductive age.
  
  
  METHODS
  A cross-sectional, population-based study.
  
  
  METHODS
  The first 130 healthy non-pregnant women (aged 16-34 years) who agreed to participate in a reproductive cohort in Morelos, Mexico.
  
  
  METHODS
  Dietary intakes of vitamin B(12) 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 B(12) intake (<2.0 microg/day), which resulted with a significant interaction (P=0.01).
  
  
  CONCLUSIONS
  Vitamin B(12) is an important determinant of Hcy levels in Mexico. Supplementation of folic acid with vitamin B(12) may be preferable when the MTHFR 677T variant allele is prevalent.
authors.affiliation: Department of Reproductive Health, National Institute of Public Health, Morelos, Mexico.
authors.forename: L
authors.initials: L
authors.lastname: Torres-Sánchez
authors.forename: J
authors.initials: J
authors.lastname: Chen
authors.forename: Y
authors.initials: Y
authors.lastname: Díaz-Sánchez
authors.forename: C
authors.initials: C
authors.lastname: Palomeque
authors.forename: T
authors.initials: T
authors.lastname: Bottiglieri
authors.forename: M
authors.initials: M
authors.lastname: López-Cervantes
authors.forename: L
authors.initials: L
authors.lastname: López-Carrillo
mesh_terms: D000293:Adolescent; D000328:Adult; D000483:Alleles; D002851:Chromatography, High Pressure Liquid; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D005260:Female; D005492:Folic Acid / Q000008:administration & dosage*; D005787:Gene Frequency; D005838:Genotype; D006710:Homocysteine / Q000097:blood*; D006801:Humans; D042965:Methylenetetrahydrofolate Reductase (NADPH2) / Q000235:genetics*; D008800:Mexico; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D011863:Radioimmunoassay; D011795:Surveys and Questionnaires; D014805:Vitamin B 12 / Q000008:administration & dosage*
chemical_list: D006710:Homocysteine; D005492:Folic Acid; D042965:Methylenetetrahydrofolate Reductase (NADPH2); D014805:Vitamin B 12