Abstract
BackgroundSerum folate concentration is lower in individuals with the methylenetetrahydrofolate reductase (MTHFR) 677TT genotype than in those with the MTHFR 677CC or 677CT genotypes. Since studies considering folate intake are limited, we examined the association between folate intake and serum folate levels, according to the genotype.MethodsThe subjects comprised 170 Japanese persons (74 males and 96 females) aged 20-75 years who visited a clinic to test for Helicobacter pylori infection. Folate intake was estimated using a semiquantitative food-frequency questionnaire, and serum folate was measured in the residual fasting blood samples of the subjects. MTHFR C677T was genotyped using polymerase chain reaction.ResultsThe geometric means of serum folate level were 6.19, 6.20, and 5.17 ng/mL among the 60 participants with the 677CC genotype, 90 participants with the 677CT genotype, and 20 participants with the 677TT genotype, respectively. No difference was noted in the mean folate intake estimated using the food-frequency questionnaire. Regression analysis showed that loge(serum folate) adjusted for age, sex, and loge(folate intake) was significantly lower among those with the 677TT genotype than among those with the 677CT or 677CC genotypes (p = 0.01). The adjusted reduction in serum folate was 20.2% (95% confidence interval, 5.4-32.6%) in the case of the 677TT genotype relative to the levels in the case of the 677CC/677CT genotypes. When folate intake was adjusted for total energy intake, using the residual method, the slope of the regression line for 677TT was smaller than those of the regression lines for 677CC and 677CT.ConclusionIndividuals with the 677TT genotype may need to consume more folate to maintain serum folate levels similar to those found in individuals with the 677CC/677CT genotypes.
Highlights
Shortage of dietary folate has been proven to elevate homocysteine levels.[1,2,3] Folate supply substantially reduces the plasma homocysteine levels among individuals with hypercysteinemia
No significant differences were observed in the age, sex, serum folate, dietary folate intake, dietary vitamin B6 intake, dietary vitamin B12 intake, energy intake, supplement use, smoking status, and alcohol consumption status
Adjustment for alcohol consumption did not substantially change the results. This cross-sectional study aimed to evaluate the effect of the methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism on the association between serum folate levels and dietary folate intake
Summary
Shortage of dietary folate has been proven to elevate homocysteine levels.[1,2,3] Folate supply substantially reduces the plasma homocysteine levels among individuals with hypercysteinemia. Low serum folate and the resultant high plasma homocysteine levels are one of the causes of neural tube defects (NTDs) in children;[4,5] neuropsychiatric conditions;[6] cardiovascular diseases, including atherosclerosis;[7,8,9,10] and cancers.[11] For the prevention of NTDs, official bodies worldwide recommend that women take 400 μg folate/day before conception and during early pregnancy. Folate intake was estimated using a semiquantitative foodfrequency questionnaire, and serum folate was measured in the residual fasting blood samples of the subjects. Regression analysis showed that loge(serum folate) adjusted for age, sex, and loge(folate intake) was significantly lower among those with the 677TT genotype than among those with the 677CT or 677CC genotypes (p = 0.01). Conclusion: Individuals with the 677TT genotype may need to consume more folate to maintain serum folate levels similar to those found in individuals with the 677CC/677CT genotypes
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