title: Association between vitamin B12-containing supplement consumption and prevalence of biochemically defined B12 deficiency in adults in NHANES III (third national health and nutrition examination survey).
abstract: OBJECTIVE
  To explore the association between vitamin B(12) (B(12))-containing supplement use, low B(12) concentrations and biochemically defined B(12) deficiency in US adults.
  
  
  METHODS
  A cross-sectional study with adjustment for survey design. Prevalence ratios for two age groups (18-50 and >50 years) were estimated using unconditional logistic models. Outcome measures included prevalence of low serum B(12) concentration (<148 pmol/l) and biochemical B(12) deficiency (serum B(12)< 148 pmol/l with concomitant homocysteine > 10 mumol/l).
  
  
  METHODS
  A population survey of health and nutritional measures.
  
  
  METHODS
  Subjects were non-institutionalized adults, aged 18 years and older, who participated in Phase 2 of NHANES III (Third National Health and Nutrition Examination Survey).
  
  
  RESULTS
  Low B(12) concentrations were less prevalent among persons consuming B(12)-containing supplements (P = 0.001) with an adjusted prevalence ratio of 0.6 (95 % CI 0.3, 1.0). Biochemical B(12) deficiency showed a similar trend (P = 0.0002), with an adjusted prevalence ratio of 0.3 (95 % CI 0.1, 0.8). Prevalence ratios were similar in adults >50 years of age, although the prevalence of low B(12) and biochemical deficiency was proportionally higher.
  
  
  CONCLUSIONS
  Consumption of B(12)-containing supplements was associated with at least 50 % lower prevalence of both low serum B(12) and biochemical B12 deficiency in a nationally representative sample of US adults, suggesting increased consumption of B(12) from supplements or from fortified foods may reduce the prevalence of B(12) deficiency. Additionally, the current Recommended Daily Allowance for B(12) of 2.4 microg may be insufficient for those aged >50 years.
authors.affiliation: Department of Neurology, Emory University School of Medicine, Atlanta, GA 30329, USA.
authors.forename: Marian L
authors.initials: ML
authors.lastname: Evatt
authors.forename: Paul D
authors.initials: PD
authors.lastname: Terry
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Ziegler
authors.forename: Godfrey P
authors.initials: GP
authors.lastname: Oakley
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D003430:Cross-Sectional Studies; D019587:Dietary Supplements / Q000706:statistics & numerical data*; D005260:Female; D005527:Food, Fortified; D006710:Homocysteine / Q000097:blood; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009749:Nutrition Surveys; D015995:Prevalence; D014481:United States / Q000453:epidemiology; D014805:Vitamin B 12 / Q000008:administration & dosage* / Q000097:blood*; D014806:Vitamin B 12 Deficiency / Q000097:blood / Q000453:epidemiology*; D055815:Young Adult
chemical_list: D006710:Homocysteine; D014805:Vitamin B 12