Relationships of Nutrient Intake and Lifestyle-Related Factors to Serum Folate and Plasma Homocysteine Concentrations in 30-69 Year-Old Japanese

Abstract

We studied non-hospitalized 30-69 y-old Japanese subjects to ascertain the influences of a 677C-T methylene-tetrahydrofolate reductase (MTHFR) genotype, nutritional intake and lifestyle-related factors on plasma homocysteine (Hcys) and serum folate concentrations. Hcys was higher and serum folate was lower in males than in females (p<0.01). The Hcys concentration was higher in the VV group than in the AA and AV groups for both males and females. However, a relatively low serum folate concentration of 1.8±7 nmol/L was found in the entire male group as compared with 22±10 nmol/L in all females. In the female subjects, serum folate concentrations differed among MTHFR genotypes, being lowest in the VV group. In all male subjects, log folate intake per 1, 000 kcal was a significant positive predictor of log serum folate concentration (p<0.01), while in females the log vitamin C intake per standard body weight was a significant positive variable (p< 0.00.1) predicting the log serum folate concentration. Smokers had significantly lower serum folate concentrations, regardless of dietary folate intake. High folate and vitamin C consumptions, appears to be beneficial to normal and heterozygous MTHFR genotype subjects for maintaining serum folate concentrations. Even a 400 μg daily intake of folate might be less than what is needed, especially for homozygous MTHFR subjects and smokers, to maintain an adequate serum folate concentration.