What's happening
High-dose calcium supplements can interfere with zinc absorption.
Recommendation
If taking both, separate timing or ensure adequate zinc intake.
Timing
Separate by 2 hours if taking high doses
Sources
- — Journal of Nutrition
calcium and zinc
Calcium may reduce zinc absorption
Frequently Asked Questions
Can I take calcium and zinc together?
Calcium may reduce zinc absorption. If taking both, separate timing or ensure adequate zinc intake.
How should I time calcium and zinc?
Separate by 2 hours if taking high doses
Is this interaction dangerous?
This interaction is rated “Caution” by Formulate. High-dose calcium supplements can interfere with zinc absorption.
Learn more about each substance
Cited research
Studies from our registry that mention calcium or zinc. Each links to the primary source and the other Formulate pages citing it.
Mentions zinc · 2017
Zinc lozenges and the common cold: a meta-analysis comparing zinc acetate and zinc gluconate, and the role of zinc dosage
Hemilä H · JRSM Open
Meta-analysis of 7 RCTs (n=575) found zinc lozenges (≥75mg/day elemental zinc) shortened cold duration by ~33%, with no significant difference between acetate and gluconate forms.
Mentions calcium · 2015
Calcium intake and risk of fracture: systematic review
Bolland et al. · BMJ
Systematic review finding little evidence that increasing calcium intake prevents fractures in community-dwelling adults.
Mentions zinc · 2013
Oral zinc for the common cold (Cochrane Review)
Singh M, Das RR · Cochrane Database of Systematic Reviews
Cochrane review of 18 RCTs found zinc reduced common cold duration and severity in healthy adults when taken within 24 hours of symptom onset, though adverse effects (taste disturbance, nausea) were common.
Mentions calcium · 2010
Iron bioavailability and dietary reference values
Hurrell R, Egli I · American Journal of Clinical Nutrition
Reviews enhancers (vitamin C, meat) and inhibitors (phytate, polyphenols, calcium) of non-heme iron absorption, providing the mechanistic basis for pairing iron with vitamin C and separating it from tea/coffee.
Mentions zinc · 2005
Zinc-induced copper deficiency: a report of three cases initially recognized on bone marrow examination
Willis et al. · American Journal of Clinical Nutrition
Documented cases of copper deficiency from chronic high-dose zinc supplementation — supports the 1–2 mg copper pairing guideline.
Mentions calcium · 2000
Prediction of dietary iron absorption: an algorithm for calculating absorption and bioavailability
Hallberg and Hulthén · American Journal of Clinical Nutrition
Foundational model for non-heme iron absorption factoring vitamin C, phytates, tannins, and calcium interactions.
Related reading
Guide
Zinc Supplement Guide 2026: Evidence-Based & Ranked
Learn which zinc forms actually shorten colds, how dosing affects testosterone and copper balance, and who faces the highest deficiency risk.
Guide
Zinc for Immune Support: Timing and Form Matter More Than Dose
Zinc genuinely shortens colds, but only when taken correctly. Lozenges within 24 hours of first symptoms — not pills, not after you're already sick.
Other interactions to know
More interactions involving calcium or zinc
- Warningzinc+copper
Zinc depletes copper over time
- Warningcalcium+iron
Calcium significantly reduces iron absorption
- Warningcalcium+thyroid medication
Calcium blocks thyroid medication absorption
- Cautionzinc+iron
Zinc and iron compete for absorption
- Cautioncalcium+magnesium
High calcium can impair magnesium absorption
- Cautionppi+calcium
PPIs reduce calcium carbonate absorption
- Synergyvitamin d+calcium
Vitamin D enhances calcium absorption
- Synergyzinc+quercetin
Quercetin acts as zinc ionophore
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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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