title: Factors affecting the distribution of folate forms in the serum of elderly German adults.
abstract: OBJECTIVE
  We investigated the roles of age, vitamin B(12) markers, and the 5,10-methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism as determinants of folate forms in serum.
  
  
  METHODS
  We measured the serum concentrations of (6S)-5-CH(3)-H(4)folate, (6S)-H(4)folate, (6S)-5-HCO-H(4)folate, (6R)-5,10-CH(+)-H(4)folate, and folic acid in 146 non-supplemented older participants (median age 74 years). The concentrations of total vitamin B(12), holotranscobalamin (holoTC), methylmalonic acid (MMA), and total homocysteine (tHcy) were also measured.
  
  
  RESULTS
  Elevated metabolites (MMA > 271 nmol/L and tHcy > 12.0 μmol/L) were found in 24.0 and 63.0 % of the participants, respectively. We found a significant age-dependent decrease (participants with a median age of 87 years compared with participants with a median age of 60 years) in the sum of serum folate levels, the (6S)-5-CH(3)-H(4)folate concentration, and the (6S)-5-CH(3)-H(4)folate proportion. In addition, participants with elevated metabolite levels were older, had lower concentrations of the sum of folates and (6S)-5-CH(3)-H(4)folate, and had higher concentrations of (6S)-5-CHO-H(4)folate and creatinine but had a comparable holoTC/total vitamin B(12) ratio. No association was found between the MTHFR C677T genotype and serum folate forms.
  
  
  CONCLUSIONS
  Low serum (6S)-5-CH(3)-H(4)folate concentrations and the proportion of (6S)-5-CH(3)-H(4)folate (percentage of the sum of folate forms) are related to older age and elevated MMA and tHcy levels.
authors.affiliation: Department of Clinical Chemistry and Laboratory Medicine, Saarland University Hospital, Homburg, Saarland, Germany.
authors.forename: Susanne H
authors.initials: SH
authors.lastname: Kirsch
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Herrmann
authors.forename: Rudolf
authors.initials: R
authors.lastname: Eckert
authors.forename: Jürgen
authors.initials: J
authors.lastname: Geisel
authors.forename: Rima
authors.initials: R
authors.lastname: Obeid
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003404:Creatinine / Q000097:blood; D019587:Dietary Supplements; D005260:Female; D005492:Folic Acid / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000097:blood*; D005838:Genotype; D005858:Germany; D006801:Humans; D008297:Male; D042965:Methylenetetrahydrofolate Reductase (NADPH2) / Q000235:genetics; D008764:Methylmalonic Acid / Q000097:blood; D008875:Middle Aged; D011110:Polymorphism, Genetic; D014805:Vitamin B 12 / Q000097:blood
chemical_list: D008764:Methylmalonic Acid; D005492:Folic Acid; D003404:Creatinine; C573423:MTHFR protein, human; D042965:Methylenetetrahydrofolate Reductase (NADPH2); D014805:Vitamin B 12