Iron for Fatigue
Verdict: Published with Warning
Across 5 PubMed studies, the evidence for Iron in Fatigue grades Tier B — preliminary evidence. Effective, but with safety or population caveats.
B 🟡 B Preliminary Evidence Published with Warning
Why this grade7-layer evidence engine
⚖️
Scoring transparency
All scores computed by a 7-layer evidence engine — fully auditableRaw score 0.67
D
C
B
A
S
← counter-evidence / ineffectiveeffective / strong evidence →
Final grade
B · Published with Warning
Confidence
85%
Highly consistent evidence
Evidence level
E1
Cochrane high-quality SR/MA
▸View the full decision path (audit trail)
- compute_raw_score — 加權公式: L2×0.30 + L3×0.25 + L5×0.25 + L11×0.10 + L1×0.10 = 0.665
- tier_from_score — 依分數區間映射至 tier letter
- apply_hec_rules — 高品質 SR/MA 顯示 positive (3 篇 > 0 negative)
- tier_strict_requirement_check — Tier 條件達標，未降階
- detect_disputes — 偵測到 0 個 hard + 0 個 soft dispute
- decide_status — 依 tier + dispute 結果決定 status
PubMed studies (5)L2 · primary research & systematic reviews
Daily iron supplementation for improving anaemia, iron status and health in menstruating women
Finding: Across 67 trials (8506 women), daily oral iron raised haemoglobin (high-certainty evidence), improved maximal and submaximal exercise performance, and appeared to reduce symptomatic fatigue, at the cost of more GI side effects (no pooled fatigue effect size reported).
View on PubMed Efficacy of iron supplementation on fatigue and physical capacity in non-anaemic iron-deficient adults: a systematic review of randomised controlled trials
Finding: Iron supplementation reduced subjective fatigue (SMD -0.38, 95% CI -0.52 to -0.23; 4 trials, 714 participants) but did NOT improve objective physical capacity (VO2max SMD 0.11, 95% CI -0.15 to 0.37).
View on PubMed Systematic review and meta-analysis of intravenous iron therapy for adults with non-anaemic iron deficiency
Finding: Across 21 RCTs (3514 participants), IV iron improved peak VO2 (MD 1.77 mL/kg/min, 95% CI 0.57-2.97) and reduced fatigue scores (SMD ~0.30, 95% CI -0.52 to -0.09) but showed no quality-of-life benefit (MD 0.15, 95% CI -0.01 to 0.31).
View on PubMed Iron deficiency without anaemia is a potential cause of fatigue: meta-analyses of randomised controlled trials and cross-sectional studies
Finding: Pooled across 6 RCTs, iron supplementation significantly reduced fatigue in non-anaemic iron-deficient patients (effect size 0.33, 95% CI 0.17-0.48; P<0.0001), whereas the cross-sectional association was non-significant (0.10, 95% CI -0.11 to 0.31; P=0.362).
View on PubMed Effect of iron supplementation on fatigue in nonanemic menstruating women with low ferritin: a randomized controlled trial
Finding: Over 12 weeks, fatigue fell 47.7% with oral iron vs 28.8% with placebo (between-group difference -18.9%, 95% CI -34.5 to -3.2; p=0.02), but haemoglobin and clinical anaemia outcomes were unchanged.
View on PubMed Regulatory & authoritative positionsL4/L5 · FDA / EMA / NIH ODS / Cochrane / Mayo …
L4a US FDA
Supportive
NUTRIENT SUPPLEMENT source↗
L4b EU EFSA
Supportive
contributes to normal oxygen transport in the body source↗
L4c UK NHS
Cautious
You should be able to get all the iron you need from your daily diet. source↗
L4d TW TFDA / 衛福部
Supportive
育齡婦女及懷孕婦女每日建議攝取鐵量為15毫克，至懷孕第3期婦女則應增加每日攝取量至45毫克。 source↗
L4e WHO
Supportive
Daily oral iron and folic acid supplementation is recommended as part of antenatal care source↗
L5a NIH Office of Dietary Supplements
Supportive
Iron is an essential component of hemoglobin source↗
L5b Mayo Clinic
Cautious
Extreme tiredness source↗
L5c Cleveland Clinic
Cautious
Without enough iron, your body can't make enough hemoglobin source↗
L5d Harvard Health
Supportive
If you don't suffer from an iron deficiency, there's no evidence that taking iron supplements for energy will be beneficial. source↗