Iron: what the evidence actually shows
Evidence by outcome
energy / fatiguegrade Ahigh certainty— reliably reduces fatigue when iron deficiency / IDA is present; no benefit when iron-replete
cognitiongrade Clow certainty— improves attention/cognition when iron deficiency is present; no benefit if replete
energy / fatiguegrade Dvery-low certainty— 21-study review: iron supplementation associated with improved fatigue scores (p-values only, no CI/n given) in non-anemic iron deficiency; the review's own meta-analyses were "limited" for most outcomes examined.
People say · Evidence shows
“everyone feels more energetic on iron”
matchesnegligiblefolk
What it probably doesn't do
- Iron for energy / fatigue — Grade D, 21-study review: iron supplementation associated with improved fatigue scores (p-values only, no CI/n given) in non-anemic iron deficiency; the review's own meta-analyses were "limited" for most outcomes examined..
Grade history
- A → ACorrection by Claude (gold-standard provenance sweep): live Postgres source drift replaced with the verified seed source set [pmid-27087396] details →
- C → CCorrection by Claude (gold-standard provenance sweep): live Postgres source drift replaced with the verified seed source set [pmid-35011099] details →
Re-review cadence: every 12 months (Grade A/B) · next scheduled by · methodology v1.
By outcome — the money pages
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sources: PMID:27087396 · PMID:35011099 · PMID:26256281
Cite this page
Reuse under CC-BY 4.0 with attribution to evidencebased.info.
Plain-text citation
Substrate. Iron: what the evidence actually shows. https://evidencebased.info/interventions/iron. Updated 2026-07-16.
BibTeX
@misc{substrate_nfointerventionsiron,
author = {Substrate editorial},
title = {Iron: what the evidence actually shows},
year = {2026},
url = {https://evidencebased.info/interventions/iron},
note = {evidencebased.info}
}