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Vitamin B12 deficiency.
Nat Rev Dis Primers. 2017 Jun 29; 3:17040.NR

Abstract

Vitamin B12 (B12; also known as cobalamin) is a B vitamin that has an important role in cellular metabolism, especially in DNA synthesis, methylation and mitochondrial metabolism. Clinical B12 deficiency with classic haematological and neurological manifestations is relatively uncommon. However, subclinical deficiency affects between 2.5% and 26% of the general population depending on the definition used, although the clinical relevance is unclear. B12 deficiency can affect individuals at all ages, but most particularly elderly individuals. Infants, children, adolescents and women of reproductive age are also at high risk of deficiency in populations where dietary intake of B12-containing animal-derived foods is restricted. Deficiency is caused by either inadequate intake, inadequate bioavailability or malabsorption. Disruption of B12 transport in the blood, or impaired cellular uptake or metabolism causes an intracellular deficiency. Diagnostic biomarkers for B12 status include decreased levels of circulating total B12 and transcobalamin-bound B12, and abnormally increased levels of homocysteine and methylmalonic acid. However, the exact cut-offs to classify clinical and subclinical deficiency remain debated. Management depends on B12 supplementation, either via high-dose oral routes or via parenteral administration. This Primer describes the current knowledge surrounding B12 deficiency, and highlights improvements in diagnostic methods as well as shifting concepts about the prevalence, causes and manifestations of B12 deficiency.

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Publisher Full Text (DOI)

Authors+Show Affiliations

Green R
Department of Pathology and Laboratory Medicine, University of California Davis, 4400 V Street, PATH Building, Davis, California 95817, USA.
Allen LH
USDA, ARS Western Human Nutrition Research Center, University of California Davis, Davis, California, USA.
Bjørke-Monsen AL
Laboratory of Clinical Biochemistry, Haukeland University Hospital, Bergen, Norway.
Brito A
USDA, ARS Western Human Nutrition Research Center, University of California Davis, Davis, California, USA.
Guéant JL
Inserm UMRS 954 N-GERE (Nutrition Génétique et Exposition aux Risques Environnementaux), University of Lorraine and INSERM, Nancy, France.
Miller JW
School of Environmental and Biological Sciences, Rutgers University, New Brunswick, New Jersey, USA.
Molloy AM
School of Medicine and School of Biochemistry and Immunology, Trinity College Dublin, University of Dublin, Dublin, Ireland.
Nexo E
Department of Clinical Medicine, Clinical Biochemistry, Aarhus University Hospital, Aarhus, Denmark.
Stabler S
Department of Medicine, University of Colorado Denver, Denver, Colorado, USA.
Toh BH
Centre for Inflammatory Diseases, Monash Institute of Medical Research, Clayton, Victoria, Australia.
Ueland PM
Laboratory of Clinical Biochemistry, Haukeland University Hospital, Bergen, Norway. Section for Pharmacology, Department of Clinical Science, University of Bergen, Bergen, Norway.
Yajnik C
Diabetes Unit, King Edward Memorial Hospital, Pune, Maharashtra, India.

MeSH

AdolescentAdultAgedAged, 80 and overBiomarkersChildChild, PreschoolFemaleHomocysteineHumansMaleMethylmalonic AcidMiddle AgedPrevalenceRisk FactorsTranscobalaminsVitamin B 12Vitamin B 12 DeficiencyYoung Adult

Pub Type(s)

Journal Article
Review

Language

eng

PubMed ID

28660890

Clinical Trial Links

Micronutrient Status During Pregnancy

Citation

Green, Ralph, et al. "Vitamin B12 Deficiency." Nature Reviews. Disease Primers, vol. 3, 2017, p. 17040.
Green R, Allen LH, Bjørke-Monsen AL, et al. Vitamin B12 deficiency. Nat Rev Dis Primers. 2017;3:17040.
Green, R., Allen, L. H., Bjørke-Monsen, A. L., Brito, A., Guéant, J. L., Miller, J. W., Molloy, A. M., Nexo, E., Stabler, S., Toh, B. H., Ueland, P. M., & Yajnik, C. (2017). Vitamin B12 deficiency. Nature Reviews. Disease Primers, 3, 17040. https://doi.org/10.1038/nrdp.2017.40
Green R, et al. Vitamin B12 Deficiency. Nat Rev Dis Primers. 2017 Jun 29;3:17040. PubMed PMID: 28660890.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Vitamin B12 deficiency. AU - Green,Ralph, AU - Allen,Lindsay H, AU - Bjørke-Monsen,Anne-Lise, AU - Brito,Alex, AU - Guéant,Jean-Louis, AU - Miller,Joshua W, AU - Molloy,Anne M, AU - Nexo,Ebba, AU - Stabler,Sally, AU - Toh,Ban-Hock, AU - Ueland,Per Magne, AU - Yajnik,Chittaranjan, Y1 - 2017/06/29/ PY - 2017/6/30/entrez PY - 2017/7/1/pubmed PY - 2018/2/6/medline SP - 17040 EP - 17040 JF - Nature reviews. Disease primers JO - Nat Rev Dis Primers VL - 3 N2 - Vitamin B12 (B12; also known as cobalamin) is a B vitamin that has an important role in cellular metabolism, especially in DNA synthesis, methylation and mitochondrial metabolism. Clinical B12 deficiency with classic haematological and neurological manifestations is relatively uncommon. However, subclinical deficiency affects between 2.5% and 26% of the general population depending on the definition used, although the clinical relevance is unclear. B12 deficiency can affect individuals at all ages, but most particularly elderly individuals. Infants, children, adolescents and women of reproductive age are also at high risk of deficiency in populations where dietary intake of B12-containing animal-derived foods is restricted. Deficiency is caused by either inadequate intake, inadequate bioavailability or malabsorption. Disruption of B12 transport in the blood, or impaired cellular uptake or metabolism causes an intracellular deficiency. Diagnostic biomarkers for B12 status include decreased levels of circulating total B12 and transcobalamin-bound B12, and abnormally increased levels of homocysteine and methylmalonic acid. However, the exact cut-offs to classify clinical and subclinical deficiency remain debated. Management depends on B12 supplementation, either via high-dose oral routes or via parenteral administration. This Primer describes the current knowledge surrounding B12 deficiency, and highlights improvements in diagnostic methods as well as shifting concepts about the prevalence, causes and manifestations of B12 deficiency. SN - 2056-676X UR - https://www.unboundmedicine.com/medline/citation/28660890/Vitamin_B12_deficiency_ L2 - https://doi.org/10.1038/nrdp.2017.40 DB - PRIME DP - Unbound Medicine ER -