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SupplementScience

Iron Research & Evidence

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Evidence Level

Strong

Iron supplementation is one of the most well-established interventions in nutritional medicine. A key finding from Vaucher et al. (2012, 7 RCTs, n=884) demonstrated that iron supplementation significantly reduced fatigue in non-anemic but iron-deficient women. Emerging research supports alternate-day dosing: Stoffel et al. (2020, published in The Lancet Haematology) showed that giving iron every other day improved fractional absorption by 40% compared to consecutive-day dosing, due to hepcidin-mediated regulation. This has shifted clinical practice toward alternate-day protocols.

Evidence by Condition

ConditionStudied DoseEvidence
Iron-deficiency anemia65mg elemental iron 1-2x dailyStrong
Non-anemic iron deficiency25-45mg elemental iron daily or every other dayStrong
Pregnancy27-60mg elemental iron daily per WHO guidelinesStrong
Athletic performance25-45mg daily for iron-depleted athletesModerate
Full Iron Guide

References

  1. (). Effect of iron supplementation on fatigue in nonanemic menstruating women with low ferritin: a randomized controlled trial. CMAJ. DOI
  2. (). Iron absorption from oral iron supplements given on consecutive versus alternate days and as single morning doses versus twice-daily split doses. The Lancet Haematology. DOI
  3. (). Iron deficiency. The Lancet. DOI