Mami Hiraoka | Search PubMed

PubMed2004

Gene-nutrient and gene-gene interactions of controlled folate intake by Japanese women.

Elevated serum total homocysteine (tHcy) levels are associated with increased risk for cardiovascular disease and dementia. The prevalence rates of homozygous mutants among Japanese women (n = 300) were 17.3%, 1.3%, 18.6%, and 5.3% for methylenetetrahydrofolate reductase (MTHFR) C677T and A1298C, reduced folate carrier (RFC-1) A80G, and methionine synthase (MS) A2756G, respectively. The tHcy value was significantly lower (p < 0.001) in young women with CC or CT of MTHFR than with TT (10.9+/-4.7 micromol/L) (n =250). Diversities of serum folate and tHcy in women with 23 combinations of different alleles at low folate intake converged to the highest (34.0+/-8.6 nmol/L) and lowest (7.6+/-1.5 micromol/L) levels, respectively, after folic acid (400 microg/day) supplementation. In the regression equation ( y= ax + b) of serum folate ( y nmol/L) plotted against mean folate intake ( x microg/day), the values of "a" were 0.032, 0.037, and 0.045 for individuals with CC, CT, and TT alleles, respectively, of MTHFR.

Adult↗

PubMed2004

Folate intake, serum folate, serum total homocysteine levels and methylenetetrahydrofolate reductase C677T polymorphism in young Japanese women.

Various factors influence folate status and requirements. To investigate the folate status in young Japanese women (n=340, 20-22 y), I determined the serum folate and total homocysteine (tHcy), and examined the influence of methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism on folate status in a subgroup of 252 of the women. I calculated folate consumption based on records of food intake weighed over 3 d using the standard Tables of Food Composition in Japan (5th revised edition) and the US Food Composition Table based on the USDA nutrient database excluding fortification. Serum folate and total homocysteine (tHcy) levels were determined by chemiluminescent-competitive protein binding assay and HPLC, respectively. The mean intake of folate was 323+/-133 and 196+/-71 microg/d, and 86.5% and 42.1% of the participants consumed more than the RDA of 200 microg of folate, according to the Japanese and US tables, respectively. The main sources of dietary folate were vegetables, green tea and bread. Serum folate levels were significantly correlated with folate intake (r=0.249, p<0.001). Serum tHcy levels were above 15 micromol/L in four participants. I found significant negative correlations between serum tHcy and folate intake (r=-0.175, p<0.05), and between serum tHcy and serum folate (r=-0.297, p<0.0001). The frequencies of the CC, CT and TT genotypes of the MTHFR gene were 32.9, 51.6 and 15.5%, respectively. Among individuals with the TT genotype, serum folate and tHcy levels were lower and higher, respectively, than in those with the other genotypes, regardless of folate intake above RDA. These data suggest that the current RDA of folate estimated based on foreign data might not be sufficient for Japanese and that this value might require reassessment.

Adult↗

PubMed2004