Does Iron help cognition? (Grade C evidence)
For cognition, Iron sits at Grade C — a hint of benefit in limited trials, especially in iron-deficient adults, low certainty, at doses 18–65 mg/day.
Exact question reviewed
- Population
- iron-deficient adults
- Intervention
- Iron · 18–65 mg/day
- Comparator
- not reported
- Outcome
- cognition
- Time horizon
- not reported
Bottom line. For cognition, Iron sits at Grade C — a hint of benefit in limited trials, especially in iron-deficient adults, low certainty, at doses 18–65 mg/day. [1 RCT]
- Direction
- benefit
- Magnitude
- improves attention/cognition when iron deficiency is present; no benefit if replete
- Grade
- C
- Certainty
- low
- Clinical meaning
- small but potentially useful
- Who it applies to
- iron-deficient adults
- Dose / form studied
- 18–65 mg/day
- Safety
- not assessed
- The one limitation
- Claim-specific limitation details are not available in this public record.
Reviewed · Evidence last changed · Claim clm_ec_b1-iron-cog v0
Grade C / low: hints of benefit in small trials; a well-run RCT could easily push this to B or to null.
Who it works for
Best-studied in iron-deficient adults. Recorded studied dose: 18–65 mg/day.
Evidence
| Study | Design | Role | Cite |
|---|---|---|---|
| Iron Status, Anemia, and Iron Interventions and Their Associations with Cognitive and Neurodevelopmental Outcomes | peer-reviewed | not classified | PMID:35011099 |
Why this grade
Reasoning trace
The current record stores Grade C at low certainty and links 1 publishable source. A claim-specific domain-by-domain grading rationale is not available in this public record, so no reason for upgrading or downgrading is inferred here.
Audit and version
- Claim ID
- ec_b1-iron-cog
- Claim version
- not reported
- Governance
- legacy, not verified
- Last evidence search
- not reported
- Last editorial review
- 2026-07-16T04:32:27.410Z
Dose & form
Studied intake: 18–65 mg/day.
How it stacks up for cognition
- Iron vs Creatine for cognition — Creatine Grade B
- Iron vs Caffeine for cognition — Caffeine Grade A
- Iron vs Lion's Mane for cognition — Lion's Mane Grade C
- Iron vs Ginkgo for cognition — Ginkgo Grade C
- Iron vs L-Theanine for cognition — L-Theanine Grade C
- Iron vs Ashwagandha for cognition — Ashwagandha Grade C
- All interventions graded for cognition →
Grade history
- 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 6 months (Grade C+) · next scheduled by · methodology v1.
Frequently asked
How long does Iron take to work for cognition?
Trials of Iron for cognition typically report effects within 2–4 weeks, though individual response varies. Studies rarely find benefit inside 1 week for chronic outcomes.
What dose was used in studies of Iron for cognition?
Studied doses for Iron in cognition trials cluster around 18–65 mg/day. See the dose block for the specific range and how it varies by form.
Does Iron work for cognition if I'm not deficient?
The effect concentrates in iron-deficient adults. If your baseline is normal, expect a smaller effect than the trial averages.
Iron or the next-best alternative for cognition?
See the compare block above for the head-to-head with the most-cited alternative. Grade + certainty differences matter more than any single trial.
Related
What this is — and is not
- Evidence description
- improves attention/cognition when iron deficiency is present; no benefit if replete
- Substrate's interpretation
- The current reviewed record assigns Grade C at low certainty. A domain-by-domain rationale is shown only when recorded.
- Discuss with a clinician
- If you're on medication or have a condition that changes the calculus, bring the interaction & population blocks above to your pharmacist or prescriber before deciding.
- Individualized medical advice
- Not provided here or on any Substrate surface (API, agent tool, embed) — see YMYL policy.
Cite this page
Citation is encouraged. The proposed reuse license is CC-BY-4.0; status: pending-governance-ratification.
Plain-text citation
Substrate. Does Iron help cognition? (Grade C). https://evidencebased.info/interventions/iron/cognition. Updated 2026-07-16.
BibTeX
@misc{substrate_entionsironcognition,
author = {Substrate editorial},
title = {Does Iron help cognition?},
year = {2026},
url = {https://evidencebased.info/interventions/iron/cognition},
note = {Grade C, evidencebased.info}
}Found something wrong on this page? Report an error →