New Research Reveals Surprising Findings About Iron Supplements

Dr. Sharon Orrange
Dr. Orrange is an Associate Professor of Clinical Medicine in the Division of Geriatric, Hospitalist and General Internal Medicine at the Keck School of Medicine of USC.
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Almost 18% of Americans take a supplement containing iron.

If you are taking iron supplements for anemia from menstrual or gastrointestinal blood loss, intriguing new results suggest taking them every other day is better than every day. Here are the details.

  1. Doctors had been suggesting daily, or even twice daily oral iron supplements for iron deficiency, despite the fact that it could cause significant gastrointestinal side effects. Turns out that was wrong.
  2. Multiple studies in the last year have shown that iron pills taken every other day, rather than every day, resulted in greater iron absorption and fewer stomach side effects.
  3. Why would every other day be better? Alternate-day dosing has a favorable effect on hepcidin – a protein that regulates intestinal iron absorption. Taking iron supplements every other day results in greater iron absorption and fewer stomach side effects.

Bottom line. Whatever dosage your doctor suggests, findings show that a single morning dose on alternate days increases iron absorption and is an effective regimen.

Dr O.


Iron absorption from oral iron supplements given on consecutive versus alternate days and as single morning doses versus twice-daily split dosing in iron-depleted women: two open-label, randomized controlled trials. Lancet Haematol. 2017;4(11).

Dietary supplement use in the United States, 2003-2006. J Nutr 2011;141:261-6.

Iron supplement use among women in the United States: science, policy and practice. J Nutr 2003;133:1974S-7S.

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