Does Iron help cognition? (Grade C evidence)

Explore current source-reported research for this exact question. These records are separate from the synthesis below; they do not update its grade or establish a recommendation.

For cognition, Iron sits at Grade C — a hint of benefit in the recorded evidence, 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 the recorded evidence, especially in iron-deficient adults, low certainty, at doses 18–65 mg/day. [1 other]

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 not reported · Evidence last changed 2026-07-16 · Open evidence record (version 0)

Grade

what does the grade mean?

Certainty

low

what does certainty mean?

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
Clinician review: Not yet reviewed by a licensed clinician
Last evidence search: not reported
Last editorial review: not verified

Public receipt · Machine-readable claim · Methodology

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

2026-07-16C → 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+) · methodology v1.

Frequently asked

How long does Iron take to work for cognition?

This record does not report a studied onset time for Iron and cognition. Do not assume a typical timeframe.

What dose was used in studies of Iron for cognition?

The recorded studied dose for Iron and cognition is 18–65 mg/day. This is a source detail, not a dose recommendation.

Does Iron work for cognition if I'm not deficient?

The recorded studied population is iron-deficient adults. This field alone does not show whether deficiency or baseline status changes the effect.

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.

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}
}

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Current source-reported research

Membership uses admitted intervention and measured-outcome associations for this exact question. Different populations, preparations, comparators and timepoints remain separate. No pooling or update to the synthesis is asserted.