Long-term PPI use reduces B12 absorption
Proton pump inhibitors (omeprazole, esomeprazole, etc.) suppress stomach acid needed to release B12 from food proteins. Use >2 years is associated with a ~65% increase in B12 deficiency risk.
If on long-term PPIs, supplement with methylcobalamin (1000mcg) or sublingual B12 which bypasses the need for gastric acid.
Take B12 supplement separately; form matters more than timing
Long-term PPI use reduces B12 absorption. If on long-term PPIs, supplement with methylcobalamin (1000mcg) or sublingual B12 which bypasses the need for gastric acid.
Take B12 supplement separately; form matters more than timing
This interaction is rated “Warning” by Formulate. Proton pump inhibitors (omeprazole, esomeprazole, etc.) suppress stomach acid needed to release B12 from food proteins. Use >2 years is associated with a ~65% increase in B12 deficiency risk.
Studies from our registry that mention ppi or vitamin b12. Each links to the primary source and the other Formulate pages citing it.
Mentions vitamin b12 · 2014
The prevalence of cobalamin deficiency among vegetarians assessed by serum vitamin B12
Pawlak et al. · European Journal of Clinical Nutrition
Systematic review finding B12 deficiency prevalence of 62% in pregnant vegetarian women, 86% in elderly vegetarians, 41% in adolescents.
Mentions vitamin b12 · 2013
Vitamin B12 deficiency
Stabler SP · New England Journal of Medicine
Comprehensive clinical review of B12 deficiency diagnosis and treatment, noting that serum B12 alone is unreliable and that methylmalonic acid (MMA) and homocysteine are more sensitive markers of functional deficiency.
Mentions vitamin b12 · 2005
Oral cyanocobalamin supplementation in older people with vitamin B12 deficiency: a dose-finding trial
Eussen SJ, de Groot LC, Clarke R, et al. · Archives of Internal Medicine
Dose-finding RCT in older adults found 647–1,032 µg/day oral B12 was needed to normalize mild B12 deficiency markers — orders of magnitude above the RDA, supporting high-dose oral as an alternative to injections.
Guide
Vitamin B12 Guide 2026: Which Form & Dose You Need
Find out if you’re actually B12 deficient — and why standard tests miss it. Covers methylcobalamin vs cyanocobalamin, dosing, and the MMA test.
Review
Methylcobalamin vs Cyanocobalamin: Which B12 Form Actually Works
Most B12 supplements use cyanocobalamin — but methylcobalamin is the bioactive form. Here's when the difference matters and when it doesn't.
Other interactions to know
Long-term antacid use depletes B12
PPIs can cause hypomagnesemia
High-dose vitamin C may reduce B12 absorption
PPIs reduce calcium carbonate absorption
PPIs reduce non-heme iron absorption
B12 and folate work together in methylation
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Medical disclaimer. This page is for educational purposes only and does not replace advice from a qualified healthcare provider.
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