NutriStack
Omeprazole and Vitamin C, a synergy.
PPIs like omeprazole reduce gastric vitamin C levels by increasing gastric pH, which oxidizes ascorbic acid to its less bioavailable form. Vitamin C supplementation can help restore depleted levels and may also improve iron absorption that is impaired by PPI-induced achlorhydria.
One pair, every claim cited. The two substances, the type, the mechanism, the recommendation, and the primary literature.
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At a glance
- Substances
- Omeprazole and Vitamin C
- Pair type
- Synergy
- Evidence (highest tier)
- Moderate
- Source citations
- 5 sources
- Stack Score effect
- +2 to your Stack Score (per scored synergy row).
- Scope
- Supplement × Prescription
- Last verified
- May 30, 2026
Synergy · Moderate evidence
Synergy
What is happening. PPIs like omeprazole reduce gastric vitamin C levels by increasing gastric pH, which oxidizes ascorbic acid to its less bioavailable form. Vitamin C supplementation can help restore depleted levels and may also improve iron absorption that is impaired by PPI-induced achlorhydria.
Mechanism. Gastric acid maintains vitamin C in its reduced, absorbable form (ascorbic acid). Omeprazole-induced pH elevation promotes oxidation to dehydroascorbic acid, which is less stable and less readily absorbed. Supplemental vitamin C bypasses this gastric degradation.
Recommendation. Consider vitamin C supplementation (250-500mg/day) if on long-term omeprazole therapy. Taking vitamin C with iron supplements can help compensate for PPI-impaired iron absorption.
Sources (5)
- Henry EB et al. Proton pump inhibitors reduce the bioavailability of dietary vitamin C. Aliment Pharmacol Ther. 2005;22(6):539-545. PMID 16167971
- 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
- Bayu P, Wibisono JJ. Vitamin C and E antioxidant supplementation may significantly reduce pain symptoms in endometriosis: A systematic review and meta-analysis of randomized controlled trials.. PLoS One. 2024. PMID 38820340
- Wen C, Li Y, Hu Q et al.. IV Vitamin C in Sepsis: A Latest Systematic Review and Meta-Analysis.. International Journal of Clinical Practice. 2023. PMID 36743822
- Jenkins DJA, Spence JD, Giovannucci EL et al.. Supplemental Vitamins and Minerals for Cardiovascular Disease Prevention and Treatment: JACC Focus Seminar.. Journal of the American College of Cardiology. 2021. PMID 33509399
Stack Score
How this pair moves the number.
Effect on the composite score
If both Omeprazole and Vitamin C are in the same stack, this pair applies +2 to your Stack Score (per scored synergy row).
The full algorithm, the clamping rules, and four worked stacks are documented at /methodology/stack-score.
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