Research statusCatalogued record, not clinically approved.
Citation presence and an automated evidence check are not medical review.
This pair has not completed NutriStack's standalone publication gate. Attached sources may mention one or both substances without establishing the stored interaction type, direction, severity, dose, management advice, or combined safety. The page is excluded from search indexing and must not be used to start, stop, or change treatment.
From the databaseWhat the row says.
Every entry follows the same shape: what is happening, the mechanism, and the recommendation.
Scope
Supplement × Supplement
Last updated
July 13, 2026
ConflictStrong evidence
What is happening. Calcium significantly inhibits both heme and non-heme iron absorption when taken simultaneously.
Mechanism. Calcium noncompetitively inhibits DMT1 and reduces ferroportin trafficking at the basolateral membrane. Calcium is NOT transported by DMT1. Reduces iron uptake by up to 50-60%.
Why it matters. Separate iron and calcium by at least 2 hours.
Recommendation. Separate iron and calcium by at least 2 hours. Take iron in the morning on an empty stomach, calcium with a different meal.
Direction. The effect runs both ways: each one influences the other.
TimingTiming & separation.
The stored record proposes this minimum window. Confirm medication schedules with a clinician or pharmacist.
Stack Score
How it moves the number.
Effect on the composite score
No numeric score interpretation is published for this unreviewed pair record.
Stack Score is a NutriStack product heuristic, not a clinical risk or benefit grade. An unreviewed database label must not be treated as a safety or benefit signal. The algorithm is documented at /methodology/stack-score.
SourcesSources, by evidence tier.
Sources attached to the record. Some support an ingredient or mechanism rather than a study of the exact pair; PMIDs link to PubMed where available.
FAQCommon Calcium + Iron questions.
Plain-language answers drawn from the interaction record on this page.
Can I take Calcium and Iron together?
NutriStack flags a potential conflict between Calcium and Iron. Do not change a prescribed treatment without clinical guidance. Calcium significantly inhibits both heme and non-heme iron absorption when taken simultaneously.
What kind of interaction is it?
Conflict: the stored record advises against combining the substances without clinician oversight.
How does this affect a NutriStack Stack Score?
No numeric score interpretation is published for this pair because its stored label has not completed source-level clinical review.
What do the cited sources establish?
NutriStack lists 3 source records with this Calcium + Iron entry. A source may support an ingredient, mechanism, or safety concern without testing the exact pair, so citation presence alone does not prove the visible verdict. Full sourcing methodology is at https://nutristackapp.com/methodology/interactions.
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