Can I Take These?

Can You Take Calcium and Iron Together?

Calcium may reduce how much iron your body absorbs from a supplement or meal.

MonitorEvidence: Moderate

What the interaction means

The NIH Office of Dietary Supplements' iron fact sheet states: "Calcium might interfere with iron absorption. Taking calcium and iron supplements at different times of the day might prevent this problem." A separate NIH-published clinical reference on dietary iron corroborates the mechanism: "Vitamin C also counteracts iron absorption inhibitors, including phytates in grains and legumes, polyphenols in tea, coffee, and red wine, and calcium in dairy products."

Why it may happen

Calcium is one of several dietary compounds (alongside phytates and polyphenols) that can compete with or inhibit iron absorption in the digestive tract.

Practical context

Neither source states a specific number of hours to separate the two -- only that taking them "at different times of the day" may help. No specific spacing interval is published here for that reason; this is a mechanism-level absorption effect, not a boxed-warning-tier interaction.

What the sources say

Dietary Iron — StatPearls, NCBI Bookshelf (National Library of Medicine)Iron — Consumer — NIH Office of Dietary Supplements

Last reviewed 2026-08-22

Medical information disclaimer: this information is general and educational. It does not diagnose conditions, prescribe treatment, or determine whether a combination is safe for you personally. Follow your prescription label and ask a pharmacist or clinician before starting, stopping, or combining products. Full disclaimer.

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