Supplements

ferritin causes fatigue

Contested Supplements 🔬 Includes disconfirming

RefutedContestedStrong support

consensus score 0.15

📅 Last reviewed: 2026-07-15 ⓘ

Evidence ladder

How far up the ladder this claim has climbed. A high consensus on a low rung means "consistent so far," not "proven in people."

Top evidence so far: All trials, pooled (Meta-analysis)

MechanismIn-vitroAnimalObservationalRCTMeta-analysis

How the studies fall

7 support 2 contradict 2 tested null 1 mixed · 12 sources, 9 independent groups

What the evidence shows

Iron deficiency (low ferritin, even without anemia) causes fatigue and cognitive symptoms; repleting iron improves them specifically in iron-deficient people.

Cochrane has no ruling yet see how our grade compares ▾

Cochrane review 2019 · limited Not directly comparable

TREATMENT question, not a causal one: it tests whether IV iron helps non-anaemic deficiency, not whether deficiency causes fatigue.

“Intravenous iron therapy for non-anaemic, iron-deficient adults (CD013084.pub2). 'Current evidence is insufficient to show benefit of intravenous iron preparations for the treatment of non-anaemic iron deficiency across a variety of patient populations.'”

Not directly comparable: their review asks a different question or reports an outcome we do not grade, so it neither corroborates nor contradicts this claim.

What is Cochrane, and why trust it?

Cochrane produces systematic reviews: instead of running a new study, they gather every trial ever done on a question, judge how well each was run, and pool the results. They take no commercial or industry funding, which is why the medical community treats their reviews as a gold standard — and why we check our own verdicts against theirs.

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The evidence (13)

Source	Grade	Stance	Quality	Finding
Lee A, Morales S, Quiroz E 2026 · Cureus	observational	supports	low	Case report: IDA pt, ferritin 1->52 ng/mL after IV iron; desiderosmia/pica-like symptom resolved fully alongside repletion.
Sultana N, Bajwa FA, Sikandar MZ, Haider MM, Majeed T 2026 · J Pak Med Assoc	RCT	supports	low	Double-blind placebo-controlled RCT, 164 non-anaemic (Hb >11 g/dl) iron-deficient women aged 18-45 with fatigue, 2 months (86 iron, 78 placebo). Abstract reports only the iron arm's pre/post change: 'In Group 1, significant decrease in fatigue score and significant increase in ferritin and haemoglobin levels were noted post-intervention (p=0.05).' No iron-vs-placebo contrast or effect size is given in the abstract (cannot-tell whether iron beat placebo). Authors conclude 'Iron supplementation alleviated fatigue'. Low quality: borderline p, within-group comparison only, and an implausible reported age SD (30.70±18.123).
Fiani D, Chahine S, Zaboube M, Solmi M, Powers JM, Calarge C 2025 · Neurosci Biobehav Rev	meta-analysis	supports	moderate	Iron supplementation improved fatigue d=0.34, cognition d=0.46, memory d=0.53; effects disappear when iron-deficient excluded (deficiency is the driver).
McErlean SME, Alam L, Baggish AL, Chung EH, Churchill TW, Corrado GD, Lewis NDH, Orchard EE, Stewart KM, Guseh JS, Cardiovascular Performance Program Study Group 2026 · JACC Case Rep	observational	supports	low	Single case report (not an n-of-1 trial): 21-year-old gymnast with exertional intolerance and orthostatic symptoms, 'ferritin: 15 μg/L, transferrin saturation: 13%) despite normal hemoglobin (14.1 g/dL)'. After 750 mg IV iron, '5 months later, iron normalized, symptoms improved, and peak oxygen consumption increased to 31.2 mL/kg/min (81% predicted)' from 25.5. Supports the direction weakly: the endpoint is exercise intolerance/VO2 rather than a fatigue scale, and recovery was confounded by post-surgery retraining and 'Propranolol (60 mg daily)'.
Kazak Salti A, Topali H, Türkmen OO 2026 · Int J Artif Organs	observational	supports	low	Hemodialysis n=78: low negative correlation between ferritin and Fatigue Severity Scale scores (direction not quantified with r/p in abstract).
Suyama A, Otsuka Y, Nakano Y, Tokumasu K, Sakurada Y, Matsuda Y, Honda H, Soejima Y, Hasegawa T, Takase R, Omura D, Oguni K, Ueda K, Otsuka F 2026 · Journal of clinical medicine	observational	tested-null	low	Long COVID n=811: low-IGF-I group had higher FAS fatigue (37.0 vs 34.0, p<0.05); IGF-I negatively correlated w/ ferritin (rho=-0.125, p<0.05) — ferritin itself only a weak secondary correlate.
Pervaz H, Rafique A, Khan HHI, Javed R, Arif S, Khaliq SS, Ghazanfar S, Ishfaq A 2026 · Cureus	observational	tested-null	low	Fibromyalgia n=241: ferritin lower in neuropathic-pain group (p=0.005) but multivariable regression showed only FIQR severity (not ferritin) independently predicted neuropathic pain.
Keller P, von Känel R, Hincapié CA, da Costa BR, Jüni P, Erlanger TE, Andina N, Niederhauser C, Lämmle B, Fontana S 2020 · Sci Rep	RCT	contradicts	high	Single 800 mg IV ferric carboxymaltose vs placebo: fatigue 3.9 vs 4.0 (p=0.819, NULL) despite ferritin +114.
Harrabi MA, Ayed R, Turki M, Boughattas W, Fendri T, Chaari F, Mezghani I, Kallel C, Rebai H, Ayadi F, Sahli S 2026 · BMC sports science, medicine & rehabilitation	RCT	mixed	low	RCT n=38, young women w/ IDA (anemic), all received iron 494.5mg; +Tabata training group had greater fatigue reduction (MFI, p<0.001) vs untrained.
Harrabi MA, Ayed R, Chaari F, Hdadi A, Boughattas W, Mezghani I, Fendri T, Kallel C, Rebai H, Turki M, Ayadi F, Sahli S 2026 · Eur J Appl Physiol	observational	supports	moderate	Off-scope. Cross-sectional, 'Forty adult women with IDA' (anaemic, outside the non-anaemic scope). The reported correlations are all with postural control: 'the center of pressure velocity (CoPv) values were significantly correlated with hemoglobin (Hb) (P < 0.01) and serum ferritin (P < 0.05) concentrations, ... and fatigue scores (P < 0.05).' No ferritin-to-fatigue association is reported in the abstract, and a cross-sectional correlation could not establish causation in any case.
Sathiyamoorthi S et al 2026 · Research Square	observational	supports	low	Cross-sectional n=171 menstruating women; 26.9% had IDWA (ferritin<30, normal Hb); fatigue reported in 77.9% of all symptomatic women (no anemic/IDWA fatigue-rate split given).
Chakraborty R, Kulkarni J, Jha A, Budihal S, Dengi A 2026 · Annals of African medicine	RCT	supports	moderate	Pregnancy IDA RCT n=60: IV FCM vs oral ferrous sulfate; ferritin 73.1 vs 22.7 ng/mL, fatigue score improvement markedly greater with IV (p<0.001). Anemic population.
Waldvogel S, Pedrazzini B, Vaucher P, Bize R, Cornuz J, Tissot JD, Favrat B 2012 · BMC Med	RCT	contradicts	high	Double-blind placebo RCT, n=154 non-anemic iron-deficient female donors (Hb>=120 g/L, ferritin<=30), 80 mg/d oral FeSO4 x4 wk: NULL on fatigue - VAS -0.15 (95% CI -0.9 to 0.6, P=0.697), FSS -0.06 (P=0.760), step test P=0.907 - despite Hb +5.2 g/L and ferritin +14.8 ng/mL (both P<0.01); powered to exclude a 1-point VAS difference. Caveat the authors attach: IDWA was ACUTE (one 450 mL donation, median pre-donation ferritin 34 ng/mL) in donors with little baseline fatigue.

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