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Human biomarkers for measuring vitamin B12 intake and status

The table below lists the various biomarkers for measuring vitamin B12 intake and status.

Table: Benefits and intricacies of biomarkers of vitamin B12 status
 BiomarkerAnalysis type  SampleBenefitsIntricacies 
 Vitamin B12  Direct analysis  Serum, plasma

Relatively sensitive and specific

Reflects long terms B12 status

Definicency occurs after several years of low intake, but within months of malabsorption
 Methylmalonic acid  Indirect analysis  Serum, urine Reflects the adequacy of B12 function of methylmalonyl mutase  Expensive instrument set-up needed (LC-MC). Increased if poor kidney function so often requires serum creatinine analysis as well.
 Holo-transcobalamin  Indirect analysis  Serum Best reflects recent intake and absorption  Gives similar prevalence of deficiency to serum B12 in surveys
 Homocysteine  Indirect analysis  Plasma Relatively sensitive but also increased by folate, B2 and B6 deficiency  
 1 to 4 of the above biomarkers combined Direct/indirect analysis   Serum, plasma The combined B12 status marker (cB12) is more specific than single biomarkers (6) Multiple analyses and instruments needed.  

Quality control and technical assistance

Laboratory accreditation and validation

ARUP Laboratories: A National Reference Laboratory is a non-profit laboratory at the University of Utah which is a global leader in clinical and pathological test development. It provides accreditation for vitamin B12 (and folate); methylmalonic acid in serum, plasma or urine; and total homocysteine in serum or plasma.  For further information, consult this page.

LabCorp (headquartered in Burlington, North Caroline, USA) is a leading global life science company. Licensure/accreditation documentation may be requested by sending an email to: Accreditation services are provided for:

For other laboratory accreditation and validation schemes, see the OpeN-Global laboratory accreditation page.


Technical assistance


For questions on methods of vitamin B12 assessment or for technical assistance, please contact or write to:


Dr. Lindsay H. Allen PhD, Center Director
USDA/ARS Western Human Nutrition Research Center, USA
University of California, Davis, USA