mineral
Calcium
Better tolerated with food; space from iron and zinc.
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Can You Take Calcium and Iron Together?
Space apart
Take these at different times
Calcium reduces iron absorption, space at least 2 hours apart.
Recommended spacing: at least 2 hours apart.
Can I take Calcium and Iron together?
Calcium reduces iron absorption, space at least 2 hours apart.
How it works
The mechanism
Calcium competes with both heme and non-heme iron for absorption at the divalent metal transporter (DMT1) in the small intestine. At doses above ~300 mg, calcium can reduce iron uptake by 50–60% when taken in the same meal.
Dose where it matters
When the interaction actually matters
The effect is dose-dependent and most pronounced with calcium ≥300 mg taken alongside iron. Trace calcium in food (e.g. a small splash of milk in coffee) is unlikely to matter.
Who should care most
Who this matters for
People supplementing for iron-deficiency anemia, menstruating women, vegetarians, and endurance athletes, anyone whose iron status is borderline.
Evidence strength
Strong evidence
Supported by multiple controlled human studies.
mineral
Iron
Best absorbed away from calcium, dairy, coffee, and tea.
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