Substrate ·evidence-based
interventions / Iron / energy / fatigue

Does Iron help energy / fatigue? (Grade A evidence)

For energy / fatigue, Iron has Grade A evidence: repeated randomised trials converge on a real, meaningful effect, especially in iron-deficient adults (esp. menstruating women). Studied doses: 18–65 mg/day.

Exact question reviewed

Population
iron-deficient adults (esp. menstruating women)
Intervention
Iron · 18–65 mg/day
Comparator
not reported
Outcome
energy / fatigue
Time horizon
not reported

Bottom line. For energy / fatigue, Iron has Grade A evidence: repeated randomised trials converge on a real, meaningful effect, especially in iron-deficient adults (esp. menstruating women). Studied doses: 18–65 mg/day. [1 RCT]

Direction
benefit
Magnitude
reliably reduces fatigue when iron deficiency / IDA is present; no benefit when iron-replete
Grade
A
Certainty
high
Clinical meaning
moderate
Who it applies to
iron-deficient adults (esp. menstruating women)
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_iron_energy v0

Grade
A
what does the grade mean?
Certainty
high
what does certainty mean?

Grade A / high: consistently helps at meaningful doses; new studies would need to reverse a large body of RCT evidence to change this.

Who it works for

Best-studied in iron-deficient adults (esp. menstruating women). Recorded studied dose: 18–65 mg/day.

Evidence

StudyDesignRoleCite
Daily iron supplementation for improving anaemia, iron status and health in menstruating womenpeer-reviewednot classifiedPMID:27087396

Why this grade

Reasoning trace

The current record stores Grade A at high 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_iron_energy
Claim version
not reported
Governance
legacy, not verified
Last evidence search
not reported
Last editorial review
2026-07-16T05:20:20.652Z

Public receipt · Machine-readable claim · Methodology

Dose & form

Studied intake: 18–65 mg/day.

People say · Evidence shows

“everyone feels more energetic on iron”

Evidence: Grade A — reliably reduces fatigue when iron deficiency / IDA is present; no benefit when iron-replete.

How it stacks up for energy / fatigue

Grade history

Re-review cadence: every 12 months (Grade A/B) · next scheduled by · methodology v1.

Frequently asked

How long does Iron take to work for energy / fatigue?

Trials of Iron for energy / fatigue 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 energy / fatigue?

Studied doses for Iron in energy / fatigue 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 energy / fatigue if I'm not deficient?

The effect concentrates in iron-deficient adults (esp. menstruating women). If your baseline is normal, expect a smaller effect than the trial averages.

Iron or the next-best alternative for energy / fatigue?

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
reliably reduces fatigue when iron deficiency / IDA is present; no benefit when iron-replete
Substrate's interpretation
The current reviewed record assigns Grade A at high 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 energy / fatigue? (Grade A). https://evidencebased.info/interventions/iron/energy. Updated 2026-07-16.
BibTeX
@misc{substrate_erventionsironenergy,
  author = {Substrate editorial},
  title  = {Does Iron help energy / fatigue?},
  year   = {2026},
  url    = {https://evidencebased.info/interventions/iron/energy},
  note   = {Grade A, evidencebased.info}
}

Found something wrong on this page? Report an error →