The Calcium Controversy: Does it Inhibit Iron Absorption or Not?

If you’ve been reading this blog for a while then chances are that you’ve seen a mention or two about iron absorption inhibitors, including calcium. This is a bit of a controversial topic since some say that calcium greatly impacts iron absorption and others say it doesn’t. It can get a little confusing when you’re getting conflicting information, so I thought it would be worth discussing further.

There is some evidence to support the impact of calcium on iron absorption, albeit from short-term studies focused on this interaction with single meals. On the other hand, long-term studies have found that calcium and milk products don’t have any adverse effect on iron absorption.


What’s the Verdict?

Unfortunately this isn’t a simple case of yes or no – hence the controversy! The actual mechanism of the interaction of calcium and iron absorption is not well understood.

The general consensus is that calcium can interfere with iron absorption on a short term basis. According to the Dietary Reference Intakes, while the interaction of calcium and iron is significantly evident in single meals, little effect has been detected in serum ferritin (circulating iron in your blood) concentrations over the long term. In addition, some studies investigating the interaction of iron and dairy products found no detrimental effect on iron absorption.


What Can You Do?

Calcium and dairy products are integral dietary components for both adults and children (and so is iron). While I’ve noted that studies have found calcium to not have a significant inhibiting effect in the long run, if you or your child is dependent on absorbing as much iron as possible, then I recommend avoiding (or at least limiting) taking iron supplements or eating iron-rich meals with calcium, just to be safe. If you’re taking an iron supplement and a calcium supplement, talk to your doctor or pharmacist about possible interactions, dosing, and the best times to take your pills.


If you still have concerns and would like to do all that you can to get the most iron from your diet and supplement, then check out my guide on How to Get the Most out of Your Iron Supplement!

Content and advice provided on The Iron Maiden is for information purposes only and should not serve as a substitute for a licensed health care provider, who is knowledgeable about an individual’s unique health care needs

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