title: Serum folate and methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism adjusted for folate intake.
abstract: BACKGROUND
  Serum 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.
  
  
  METHODS
  The 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.
  
  
  RESULTS
  The 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 log(e)(serum folate) adjusted for age, sex, and log(e)(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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Preventive Medicine/Biostatistics and Medical Decision Making, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan. kaz-n@med.nagoya-u.ac.jp
authors.forename: Kazuko
authors.initials: K
authors.lastname: Nishio
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Goto
authors.forename: Takaaki
authors.initials: T
authors.lastname: Kondo
authors.forename: Shimon
authors.initials: S
authors.lastname: Ito
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Ishida
authors.forename: Sayo
authors.initials: S
authors.lastname: Kawai
authors.forename: Mariko
authors.initials: M
authors.lastname: Naito
authors.forename: Kenji
authors.initials: K
authors.lastname: Wakai
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Hamajima
mesh_terms: D000328:Adult; D000368:Aged; D000465:Algorithms; D015415:Biomarkers / Q000097:blood; D016001:Confidence Intervals; D005260:Female; D005492:Folic Acid / Q000008:administration & dosage / Q000097:blood*; D005838:Genotype; D016481:Helicobacter Infections / Q000097:blood* / Q000201:enzymology* / Q000453:epidemiology / Q000235:genetics; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008297:Male; D042965:Methylenetetrahydrofolate Reductase (NADPH2) / Q000235:genetics*; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D012044:Regression Analysis; D012189:Retrospective Studies; D011795:Surveys and Questionnaires; D014803:Vitamin B Complex / Q000008:administration & dosage / Q000097:blood*
chemical_list: D015415:Biomarkers; D014803:Vitamin B Complex; D005492:Folic Acid; D042965:Methylenetetrahydrofolate Reductase (NADPH2)