NutriStack
Lansoprazole and Vitamin B12, a caution.
Lansoprazole reduces vitamin B12 absorption from food over years of use. The Kaiser Permanente case-control study linked two or more years of any PPI to a 65% higher risk of B12 deficiency, with dose-dependence. Elderly patients and those on long-term acid suppression are most affected.
One pair, every claim cited. The two substances, the type, the mechanism, the recommendation, and the primary literature.
Same shape as the other 1,729 pairs in the public database.
From the interaction database
What the row says.
Every entry follows the same shape: what is happening, the mechanism, the recommendation, and the primary literature.
At a glance
- Substances
- Lansoprazole and Vitamin B12
- Pair type
- Caution
- Evidence (highest tier)
- Strong
- Source citations
- 2 sources
- Stack Score effect
- −5 to your Stack Score (per scored caution row).
- Scope
- Supplement × Prescription
- Last verified
- May 30, 2026
Caution · Strong evidence
Caution
What is happening. Lansoprazole reduces vitamin B12 absorption from food over years of use. The Kaiser Permanente case-control study linked two or more years of any PPI to a 65% higher risk of B12 deficiency, with dose-dependence. Elderly patients and those on long-term acid suppression are most affected.
Mechanism. Lansoprazole irreversibly inhibits the gastric proton pump, raising gastric pH and impairing pepsin-mediated release of cobalamin from dietary proteins. Without that release, intrinsic factor cannot bind cobalamin for ileal absorption.
Recommendation. If you take lansoprazole for more than two years, ask for a serum B12 (with methylmalonic acid if borderline) annually. A daily B12 supplement, preferably methylcobalamin, sidesteps the acid-dependent absorption step.
Sources (2)
- Lam JR, Schneider JL, Zhao W, Corley DA. Proton pump inhibitor and histamine 2 receptor antagonist use and vitamin B12 deficiency. JAMA. 2013;310(22):2435-42. PMID 24327038
- Choudhury A, Jena A, Jearth V, et al. Vitamin B12 deficiency and use of proton pump inhibitors: a systematic review and meta-analysis. Expert Rev Gastroenterol Hepatol. 2023;17(5):479-87. PMID 37060552
Stack Score
How this pair moves the number.
Effect on the composite score
If both Lansoprazole and Vitamin B12 are in the same stack, this pair applies −5 to your Stack Score (per scored caution row).
The full algorithm, the clamping rules, and four worked stacks are documented at /methodology/stack-score.
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