title: Serum homocysteine and folate concentrations among a US cohort of adolescents before and after folic acid fortification.
abstract: OBJECTIVE
  We assessed serum homocysteine (tHcy) and folate concentrations among US adolescents before and after fortification of cereal-grain products with folic acid, and associations with demographic, behavioural and physiological factors.
  
  
  METHODS
  Observational study conducted among participants of a randomized trial.
  
  
  METHODS
  The Child and Adolescent Trial for Cardiovascular Health (CATCH) study.
  
  
  METHODS
  Adolescents (n 2445) in grades 8 (pre-fortification, mean age 14 years) and 12 (post-fortification, mean age 18 years).
  
  
  RESULTS
  Average serum concentrations of tHcy, folate and vitamin B6 increased by 17 %, 16 % and 14 %, respectively, while serum concentrations of vitamin B12 decreased by 11 % post-fortification. Folic acid fortification provided, on average, an additional intake of 118 μg folate/d. Male sex (P < 0.0001) and white race (P = 0.0008) were associated with significantly greater increases in tHcy concentration, while increases in BMI (P = 0.006) and serum folate concentration (P < 0.0001) were associated with significant decreases in tHcy concentration. Female sex (P < 0.0001), non-smoking (P < 0.0001), use of multivitamins (P < 0.0001) and higher dietary intake of folate (P = 0.001) were associated with significantly greater increases in serum folate concentrations. From grade 8 to grade 12, the upward age trend in serum tHcy concentration was uninterrupted in its course (P > 0.50); whereas serum folic acid concentration showed a downward trend that incurred a discrete jump upward (17 % higher; P < 0.0001) with fortification. These trends differed significantly for males v. females (P < 0.001 for interaction).
  
  
  CONCLUSIONS
  Fortification had a significant impact on improving folate status but not serum tHcy concentrations among US adolescents.
authors.affiliation: Cardiovascular Health Research Unit, University of Washington, 1730 Minor Avenue, Suite #1360, Seattle, WA 98101, USA. danenq@u.washington.edu
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Enquobahrie
authors.forename: Henry A
authors.initials: HA
authors.lastname: Feldman
authors.forename: Deanna H
authors.initials: DH
authors.lastname: Hoelscher
authors.forename: Lyn M
authors.initials: LM
authors.lastname: Steffen
authors.forename: Larry S
authors.initials: LS
authors.lastname: Webber
authors.forename: Michelle M
authors.initials: MM
authors.lastname: Zive
authors.forename: Eric B
authors.initials: EB
authors.lastname: Rimm
authors.forename: Meir J
authors.initials: MJ
authors.lastname: Stampfer
authors.forename: Stavroula K
authors.initials: SK
authors.lastname: Osganian
mesh_terms: D000293:Adolescent; D015992:Body Mass Index; D002523:Edible Grain; D005260:Female; D005492:Folic Acid / Q000008:administration & dosage* / Q000097:blood* / Q000378:metabolism; D005494:Folic Acid Deficiency / Q000097:blood / Q000453:epidemiology*; D005527:Food, Fortified; D006710:Homocysteine / Q000097:blood*; D006801:Humans; D008297:Male; D009752:Nutritional Status; D017063:Outcome Assessment, Health Care; D012737:Sex Factors; D014481:United States / Q000453:epidemiology; D025101:Vitamin B 6 / Q000097:blood; D014803:Vitamin B Complex / Q000008:administration & dosage / Q000097:blood / Q000378:metabolism
chemical_list: D006710:Homocysteine; D014803:Vitamin B Complex; D025101:Vitamin B 6; D005492:Folic Acid