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Nutrients and interactions

Supplements if you take omeprazole or another acid reducer

Proton pump inhibitors such as omeprazole are linked to low magnesium in two meta-analyses of observational studies, with higher odds at high doses, and less stomach acid means less iron, calcium carbonate and food B12 absorbed. The link to B12 deficiency is weaker than often claimed, so testing beats guessing. Picks are ranked by how strong the evidence is that the drug lowers each nutrient. This page is about nutrients and interactions: never stop or change an acid reducer without your prescriber.

This page covers nutrients and supplement interactions. Never stop or change a prescribed medication without your prescriber, and check any new supplement with your pharmacist.

Evidence last reviewed: October 2026

Solid options

OptionEvidenceBest forThe honest note
Magnesium Moderate evidence long-term or high-dose PPI users PPI users had 1.71 times the adjusted odds of low magnesium in a 16-study meta-analysis, and high doses raised the odds further. Ask for a blood level first; 200–400 mg of elemental magnesium a day is the usual range, and kidney impairment needs medical guidance. View

Situational

OptionEvidenceBest forThe honest note
Vitamin B12 Strong evidence years of acid suppression A 25-study meta-analysis found only slightly higher odds of B12 deficiency in PPI users (OR 1.42) with marked heterogeneity, so test before assuming. If you are low, supplemental B12 does not need stomach acid and works fine. View
Calcium Citrate Moderate evidence if you need a calcium supplement In fasting people without stomach acid, fractional absorption was 0.45 from citrate versus 0.04 from carbonate, which makes citrate the sensible form on a long-term PPI. Supplement only if food does not cover about 1,000–1,200 mg a day. View
Iron Bisglycinate Moderate evidence confirmed low ferritin only Less stomach acid means less iron absorbed, and one meta-analysis found a higher risk of iron deficiency anemia in PPI users (RR 2.56). Supplement only after a ferritin test, expect slower repletion, and discuss the dose with your prescriber. View

Skip, or avoid with this medication

  • Betaine HCl Limited evidence

    It adds acid back into a stomach the drug is deliberately keeping non-acidic, so do not combine them, especially if the PPI treats erosive esophagitis or Barrett's esophagus.

  • Digestive Bitters Limited evidence

    Bitters increase gastric acid secretion, which opposes the drug, and their bloating and digestion claims have almost no trial support.

  • Calcium Carbonate Moderate evidence

    It needs stomach acid to dissolve, so absorption drops on a PPI; if you use it anyway, take it with a meal, or switch to calcium citrate.

  • DGL Licorice Limited evidence

    It is sold for reflux, but there are no controlled trials of DGL for GERD, and it should never stand in for H. pylori testing.

  • Zinc Carnosine Moderate evidence

    Its reflux and gut-healing claims have essentially no trial support, and it is not established as a replacement for proton pump inhibitors.

Our verdict

If you have taken a PPI for a long time, ask for magnesium and B12 levels rather than supplementing blind, and use calcium citrate instead of carbonate if you need calcium. Skip betaine HCl and digestive bitters, which add acid back and work directly against the drug.

Key studies