title: Plasma vitamin B-12 concentrations relate to intake source in the Framingham Offspring study.
abstract: BACKGROUND
  Low vitamin B-12 status is prevalent among the elderly, but few studies have examined the association between vitamin B-12 status and intake.
  
  
  OBJECTIVE
  We hypothesized that vitamin B-12 concentrations vary according to intake source.
  
  
  METHODS
  Plasma concentrations and dietary intakes were assessed cross-sectionally for 2999 subjects in the Framingham Offspring Study. The prevalence of vitamin B-12 concentrations <148, 185, and 258 pmol/L was examined by age group (26-49, 50-64, and 65-83 y), supplement use, and the following food intake sources: fortified breakfast cereal, dairy products, and meat.
  
  
  RESULTS
  Thirty-nine percent of subjects had plasma vitamin B-12 concentrations <258 pmol/L, 17% had concentrations <185 pmol/L, and 9% had concentrations <148 pmol/L, with little difference between age groups. Supplement users were significantly less likely than non-supplement-users to have concentrations <185 pmol/L (8% compared with 20%, respectively). Among non-supplement-users, there were significant differences between those who consumed fortified cereal >4 times/wk (12%) and those who consumed no fortified cereal (23%) and between those in the highest and those in the lowest tertile of dairy intake (13% compared with 24%, respectively), but no significant differences by meat tertile. Regression of plasma vitamin B-12 on log of intake, by source, yielded significant slopes for each contributor adjusted for the others. For the total group, b = 40.6 for vitamin B-12 from vitamin supplements. Among non-supplement-users, b = 56.4 for dairy products, 35.2 for cereal, and 16.7 for meat. Only the meat slope differed significantly from the others.
  
  
  CONCLUSIONS
  In contrast with previous reports, plasma vitamin B-12 concentrations were associated with vitamin B-12 intake. Use of supplements, fortified cereal, and milk appears to protect against lower concentrations. Further research is needed to investigate possible differences in bioavailability.
authors.affiliation: Jean Mayer Human Nutrition Research Center on Aging at Tufts University, Boston MA 02111, USA. tucker@hnrc.tufts.edu
authors.forename: K L
authors.initials: KL
authors.lastname: Tucker
authors.forename: S
authors.initials: S
authors.lastname: Rich
authors.forename: I
authors.initials: I
authors.lastname: Rosenberg
authors.forename: P
authors.initials: P
authors.lastname: Jacques
authors.forename: G
authors.initials: G
authors.lastname: Dallal
authors.forename: P W
authors.initials: PW
authors.lastname: Wilson
authors.forename: J
authors.initials: J
authors.lastname: Selhub
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D003611:Dairy Products; D004032:Diet; D019587:Dietary Supplements; D002523:Edible Grain; D005260:Female; D005502:Food; D005527:Food, Fortified; D006801:Humans; D008297:Male; D008460:Meat; D008875:Middle Aged; D012737:Sex Factors; D014805:Vitamin B 12 / Q000008:administration & dosage / Q000097:blood*
chemical_list: D014805:Vitamin B 12