Influence of the C677T Polymorphism of the MTHFR Gene on Oxidative Stress in Women With Overweight or Obesity: Response to a Dietary Folate Intervention.

The C677T polymorphism of the methylenetetrahydrofolate reductase gene (MTHFR) is related to folate metabolism and can alter the levels of biochemical markers. Objective: Investigate the influence of the MTHFR C677T polymorphism on the effects of a dietary folate intervention on oxidative stress in women with overweight or obesity. Methods: Forty-eight adult women with overweight or obesity were subjected to a 24-hour dietary recall, anthropometric measurements, biochemical analysis, and genotyping of the MTHFR C677T polymorphism. They were allocated by convenience sampling to 2 groups, which received 300 g of folate-rich vegetables containing 191 mu g/d (Group 1) (n = 24) or 95 mu g/d (Group 2) (n = 24) of folate for 8 weeks. Results: The dietary intervention increased the serum folic acid levels in the 2 analyzed groups. The intervention with 191 mu g/d of folate led to relevant results in terms of homocysteine levels (p = 0.0005) and total antioxidant capacity (p = 0.0261); the effect was larger among carriers of the TT genotype. Conclusions: The study demonstrated the beneficial effect of folate intake in terms of a TAC elevation for the CC and TT genotypes of the MTHFR C677T polymorphism, an increase in folic acid levels for all genotypes, and a reduction in the Hcy levels for the TT genotype in response to an intervention consisting of an intake of 191 mu g/d of folate supplied by vegetables.