NutriStack
Calcium and Omeprazole, a caution.
Long-term omeprazole use reduces calcium absorption, particularly from calcium carbonate which requires an acidic environment for dissolution. This has been associated with increased fracture risk in observational studies, prompting an FDA warning about PPI use and fracture risk.
One pair, every claim cited. The two substances, the type, the mechanism, the recommendation, and the primary literature.
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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
- Calcium and Omeprazole
- Pair type
- Caution
- Evidence (highest tier)
- Moderate
- Source citations
- 4 sources
- Stack Score effect
- −5 to your Stack Score (per scored caution row).
- Scope
- Supplement × Prescription
- Last verified
- May 30, 2026
Caution · Moderate evidence
Caution
What is happening. Long-term omeprazole use reduces calcium absorption, particularly from calcium carbonate which requires an acidic environment for dissolution. This has been associated with increased fracture risk in observational studies, prompting an FDA warning about PPI use and fracture risk.
Mechanism. Calcium carbonate requires gastric acid for dissolution and ionization into absorbable Ca2+. Omeprazole raises gastric pH, reducing calcium carbonate solubility. Calcium citrate is pH-independent and is better absorbed during PPI therapy.
Recommendation. If on long-term omeprazole, consider using calcium citrate instead of calcium carbonate, as citrate does not require gastric acid for absorption. Ensure adequate vitamin D intake and consider bone density monitoring.
Sources (4)
- Yang YX et al. Long-term proton pump inhibitor therapy and risk of hip fracture. JAMA. 2006;296(24):2947-2953. PMID 17190895
- Choudhury A, Jena A, Jearth V, Dutta AK et al.. Vitamin B12 deficiency and use of proton pump inhibitors: a systematic review and meta-analysis. Expert Review of Gastroenterology & Hepatology. 2023. PMID 37060552
- Liu C, Kuang X, Li K, Guo X, Deng Q, Li D. Effects of combined calcium and vitamin D supplementation on osteoporosis in postmenopausal women: a systematic review and meta-analysis of randomized controlled trials. Food & Function. 2020. PMID 33237064
- Yao P, Bennett D, Mafham M et al.. Vitamin D and Calcium for the Prevention of Fracture: A Systematic Review and Meta-analysis. JAMA Network Open. 2019. PMID 31860103
Stack Score
How this pair moves the number.
Effect on the composite score
If both Calcium and Omeprazole 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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