title: Steady state folate concentrations achieved with 5 compared with 1.1 mg folic acid supplementation among women of childbearing age.
abstract: BACKGROUND
  Synthetic folic acid (0.4-1.0 mg) consumed during the periconceptional period has been shown to reduce the risk of neural tube defects. Women with poor supplement adherence or a previous pregnancy affected by a neural tube defect may need to take higher doses of folic acid (4-5 mg). However, there are limited data on the pharmacokinetics of higher folic acid doses.
  
  
  OBJECTIVE
  Our aim was to compare steady state folate concentrations in women of childbearing age who took 5 or 1.1 mg folic acid daily for 30 wk.
  
  
  METHODS
  Forty nonpregnant women aged between 18 and 45 y, who did not take folic acid supplements, were enrolled in the study. Subjects were randomly assigned to take either 5 or 1.1 mg folic acid daily for 30 wk. Plasma and red blood cell (RBC) folate concentrations were measured at baseline and at weeks 2, 4, 6, 12, and 30.
  
  
  RESULTS
  There was no significant difference in baseline RBC folate concentrations between the 2 groups (1121 +/- 410 and 1035 +/- 273 nmol/L for the 5- and 1.1-mg folic acid groups, respectively). Significant differences in RBC folate were detected between groups at weeks 4, 6, 12, and 30. RBC folate concentrations by week 30 were 2339 +/- 782 and 1625 +/- 339 nmol/L for the 5- and 1.1-mg folic acid groups, respectively.
  
  
  CONCLUSIONS
  The use of 5 mg folic acid among women of childbearing age produced higher blood folate concentrations, with a faster rate of folate accumulation, compared with 1.1 mg folic acid.
authors.affiliation: Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, ON, Canada.
authors.forename: Patricia
authors.initials: P
authors.lastname: Nguyen
authors.forename: Carolyn
authors.initials: C
authors.lastname: Tam
authors.forename: Deborah L
authors.initials: DL
authors.lastname: O'Connor
authors.forename: Bhushan
authors.initials: B
authors.lastname: Kapur
authors.forename: Gideon
authors.initials: G
authors.lastname: Koren
mesh_terms: D000293:Adolescent; D000328:Adult; D019587:Dietary Supplements; D004305:Dose-Response Relationship, Drug; D004912:Erythrocytes / Q000378:metabolism*; D005260:Female; D005492:Folic Acid / Q000008:administration & dosage* / Q000097:blood* / Q000493:pharmacokinetics; D006801:Humans; D008875:Middle Aged; D009436:Neural Tube Defects / Q000517:prevention & control*; D010349:Patient Compliance; D011446:Prospective Studies; D011795:Surveys and Questionnaires; D055815:Young Adult
chemical_list: D005492:Folic Acid