Why should calcium and iron supplements be separated by at least two hours?

• A. They can interfere with each other's absorption.
• B. They improve each other's absorption.
• C. They have no interaction.
• D. They should be taken together with meals.

Answer: (A)

Calcium and iron compete for absorption in the gut. Calcium can bind iron and form a less soluble complex, which reduces how much iron (and vice versa, how much calcium) the body can absorb when both are taken together. By spacing their doses at least two hours apart, you minimize this competition and improve absorption of each mineral. That’s why separation is recommended rather than taking them at the same time. Taking them with meals isn’t ideal for iron absorption either, since meals can slow absorption and the minerals remain in the gut together; if you must take both, taking iron first and calcium a couple of hours later is a practical approach.