Daily intake of 4 to 7 microg dietary vitamin B-12 is associated with steady concentrations of vitamin B-12-related biomarkers in a healthy young population

Am J Clin Nutr. 2010 Mar;91(3):571-7. doi: 10.3945/ajcn.2009.28082. Epub 2010 Jan 13.


Background: Studies have questioned whether the current Recommended Dietary Allowance (RDA) of 2.4 microg vitamin B-12/d is adequate.

Objective: We examined the association between dietary vitamin B-12 intake and biomarkers of vitamin B-12 status.

Design: Dietary vitamin B-12 intake was estimated, and biomarkers of vitamin B-12 status were measured, in healthy men and women (n = 299; age range: 18-50 y) who were recruited from a Florida community. The National Cancer Institute Diet History Questionnaire was used. Plasma cobalamin, total transcobalamin, holo-transcobalamin, methylmalonic acid (MMA), total homocysteine (tHcy), and autoantibodies against intrinsic factor (IF) and Helicobacter pylori were analyzed in blood samples.

Results: Antibodies to H. pylori were detected in 12% of subjects (35/299), and negative results for IF antibodies were obtained for all subjects. The intake of vitamin B-12 correlated significantly with cobalamin, holo-transcobalamin, MMA, and tHcy. Subjects were divided into quintiles on the basis of their dietary vitamin B-12 intake (range: 0.42-22.7 microg/d), and biomarkers of vitamin B-12 status were plotted against estimated dietary vitamin B-12 intake. All biomarkers appeared to level off at a daily dietary vitamin B-12 intake between 4.2 and 7.0 microg.

Conclusion: In persons with normal absorption, our data indicate that an intake of 4-7 microg vitamin B-12/d is associated with an adequate vitamin B-12 status, which suggests that the current RDA of 2.4 microg vitamin B-12/d might be inadequate for optimal biomarker status even in a healthy population between 18 and 50 y of age.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Adolescent
  • Adult
  • Antibodies, Bacterial / blood*
  • Autoantibodies / blood
  • Biomarkers / blood
  • Diet*
  • Dose-Response Relationship, Drug
  • Female
  • Helicobacter pylori / immunology
  • Homocysteine / blood
  • Humans
  • Intrinsic Factor / immunology
  • Male
  • Methylmalonic Acid / blood
  • Middle Aged
  • Nutrition Policy
  • Nutritional Requirements
  • Nutritional Status*
  • Reference Values
  • Vitamin B 12 / administration & dosage*
  • Vitamin B 12 / blood
  • Vitamin B Complex / administration & dosage*
  • Vitamin B Complex / blood
  • Young Adult


  • Antibodies, Bacterial
  • Autoantibodies
  • Biomarkers
  • Homocysteine
  • Vitamin B Complex
  • Methylmalonic Acid
  • Intrinsic Factor
  • Vitamin B 12