Vitamin B12 levels during prolonged treatment with proton pump inhibitors

J Clin Gastroenterol. 2000 Jan;30(1):29-33. doi: 10.1097/00004836-200001000-00006.


Reduced serum vitamin B12 (cobalamin) levels have been documented occasionally during long-term treatment with a proton pump inhibitor (PPI) in selected groups of patients. This has largely been confined to patients being treated for Zollinger-Ellison syndrome who have sustained drug-induced achlorhydria, which does not ordinarily occur during treatment with a PPI. An appreciation of normal cobalamin metabolism and the pharmacological action of the PPIs adequately explain the mechanism for this reduction. PPIs do not promote the development of pernicious anemia.

Publication types

  • Review

MeSH terms

  • Absorption
  • Gastric Acid / metabolism*
  • Gastric Mucosa / metabolism*
  • Humans
  • Proton Pump Inhibitors*
  • Time Factors
  • Vitamin B 12 / blood*
  • Vitamin B 12 Deficiency / blood
  • Vitamin B 12 Deficiency / physiopathology*


  • Proton Pump Inhibitors
  • Vitamin B 12