Iron
Mineral ·Exploratory record · not publication-reviewed ·Updated July 13, 2026
Essential for oxygen transport via hemoglobin, energy production, and immune function. Most common nutritional deficiency worldwide, especially in women.
Exploratory record, not a reviewed medical publication.
See the editorial and medical-review policies for the publication gate.
This generated database record has not completed a claim-level review by a qualified human medical reviewer. Bibliography links and evidence labels are not approval. The page remains available for reference and is excluded from search indexing.
What the research says.
A quick, data-only summary. The full evidence, dosing, and sources are below.
Iron is a mineral most often used for oxygen transport, energy production, immune function. NutriStack rates the overall evidence as strong. A typical adult dose is 18–45 mg daily (higher doses only under medical supervision for confirmed deficiency), commonly taken as iron bisglycinate (gentle, well-absorbed) or ferrous sulfate (standard). This profile indexes 21 sources.
The bottom line
Evidence rating strong. Most-documented uses: oxygen transport, energy production, immune function. 21 sources indexed (2003–2025), with 0 interaction records on file.
How it works, mechanistically.
Core mechanism
Central atom in heme groups of hemoglobin (carries oxygen in red blood cells) and myoglobin (stores oxygen in muscle). Component of cytochrome enzymes in the electron transport chain for ATP production. Required for DNA synthesis and immune cell proliferation.1,6
Dosing & protocol.
Take on empty stomach with 50-100mg vitamin C for best absorption; avoid with calcium, tea, or coffee. Alternate-day morning dosing may provide 33% higher cumulative absorption due to hepcidin cycling.1,3
What it actually costs.
Real-world pricing across three quality tiers. Assumes Ferrous Sulfate.
Assumes about 18-45 mg elemental iron/day unless a clinician directs higher dosing. Ferrous sulfate is usually cheapest, but GI side effects can make it a false economy if adherence drops. Updated 2026-04-02.
The same dose, as food.
How much you'd eat to match a supplemental dose.
Heme iron from animal foods is absorbed much better than non-heme iron from plants.
Food-first approaches work best when deficiency is mild or prevention is the goal.
Full safety detail.
Side effects
- Constipation
- Nausea
- Dark stools
- GI distress
Sources, by evidence tier.
Numbered references. Citations throughout the page link here.
Meta-analyses & systematic reviews
14- 1Optimal dose and duration of iron supplementation for treating iron deficiency anaemia in children and adolescents: A systematic review and meta-analysisPMIDRehman T, Agrawal R, Ahamed F et al. · PLoS One · 2025
In 28 studies with 8,829 participants, pooled Hb improvement was 2.01 g/dL (95% CI 1.48-2.54). Low-dose iron (<5 mg/kg/day) with treatment durations <3 months or >6 months was optimal for improving hemoglobin levels.
- 2Systematic Review of the Effects of Iron on Cardiovascular, Kidney, and Safety Outcomes in Patients With CKDPMIDChan B, Varghese A, Badve SV et al. · Kidney international reports · 2025
Chan B, Varghese A, Badve SV et al.. Systematic Review of the Effects of Iron on Cardiovascular, Kidney, and Safety Outcomes in Patients With CKD. Kidney international reports. 2025
- 3Psychiatric and cognitive outcomes of iron supplementation in non-anemic children, adolescents, and menstruating adults: A meta-analysis and systematic reviewPMIDFiani D, Chahine S, Zaboube M et al. · Neuroscience and biobehavioral reviews · 2025
Fiani D, Chahine S, Zaboube M et al.. Psychiatric and cognitive outcomes of iron supplementation in non-anemic children, adolescents, and menstruating adults: A meta-analysis and systematic review. Neuroscience and biobehavioral reviews. 2025
- 4Impact of TMPRSS6 Genetic Variants on Maternal Iron Status in Pregnancy: A Systematic ReviewPMIDFauzan R, Defrin, Susmiati et al. · Birth defects research · 2025
Fauzan R, Defrin, Susmiati et al.. Impact of TMPRSS6 Genetic Variants on Maternal Iron Status in Pregnancy: A Systematic Review. Birth defects research. 2025
- 5Effects of iron supplementation on cognitive development in school-age children: Systematic review and meta-analysisPMIDLow M et al. · PLoS One · 2023
Iron supplementation significantly improved intelligence, attention and concentration, and memory in school-age children across 13 studies
- 6The effects of oral ferrous bisglycinate supplementation on hemoglobin and ferritin concentrations in adults and children: a systematic review and meta-analysis of randomized controlled trialsPMIDFischer JAJ, Cherian AM, Bone JN, Karakochuk CD · Nutrition Reviews · 2023
In 17 RCTs, ferrous bisglycinate resulted in higher hemoglobin in pregnant women (SMD 0.54 g/dL, P<0.01) and fewer GI adverse events (IRR 0.36, P<0.01) compared to other iron supplements.
- 7Iron supplements in pregnant women with normal iron status: A systematic review and meta-analysisPMIDHansen R, Sejer EPF, Holm C, Schroll JB · Acta Obstetricia et Gynecologica Scandinavica · 2023
In 8 RCTs with 2,822 women, daily oral iron supplementation in pregnancy reduced iron deficiency anemia at term (RR 0.51, 95% CI 0.38-0.70) and low birthweight incidence (RR 0.30, 95% CI 0.13-0.68).
- 8Effectiveness of Dietary Interventions to Treat Iron-Deficiency Anemia in Women: A Systematic Review of Randomized Controlled TrialsPMIDSkolmowska D, Głąbska D, Kołota A et al. · Nutrients · 2022
Skolmowska D, Głąbska D, Kołota A et al.. Effectiveness of Dietary Interventions to Treat Iron-Deficiency Anemia in Women: A Systematic Review of Randomized Controlled Trials. Nutrients. 2022
- 9Effectiveness of Dietary Interventions in Prevention and Treatment of Iron-Deficiency Anemia in Pregnant Women: A Systematic Review of Randomized Controlled TrialsPMIDSkolmowska D, Głąbska D, Kołota A et al. · Nutrients · 2022
Skolmowska D, Głąbska D, Kołota A et al.. Effectiveness of Dietary Interventions in Prevention and Treatment of Iron-Deficiency Anemia in Pregnant Women: A Systematic Review of Randomized Controlled Trials. Nutrients. 2022
- 10Daily iron supplementation for improving anaemia, iron status and health in menstruating womenPMIDLow MSY et al. · Cochrane Database Syst Rev · 2016
Daily iron supplementation effectively improved iron status and reduced anaemia in menstruating women
- 11Ferrous sulfate supplementation causes significant gastrointestinal side-effects in adults: a systematic review and meta-analysisPMIDTolkien Z et al. · PLoS One · 2015
Ferrous sulfate significantly increased GI side-effect risk vs placebo (OR 2.32) and vs IV iron (OR 3.05)
- 12Iron supplementation benefits physical performance in women of reproductive age: a systematic review and meta-analysisPMIDPasricha SR et al. · J Nutr · 2014
Iron supplementation improved VO2max and submaximal exercise performance in women of reproductive age
- 13Iron supplementation during pregnancy and birthweight: a randomized controlled trialHaider BA, Olofin I, Wang M et al. · BMJ · 2013
- 14Iron supplementation and cognition in children: a systematic review and meta-analysisFalkingham M, Abdelhamid A, Curtis P et al. · Nutr J · 2010
Randomized controlled trials
4- 15Alternate-day versus daily oral iron supplementation in patients with iron deficiency anemia: a randomized studyStoffel NU, Cercamondi CI, Brittenham G et al. · Am J Hematol · 2020
- 16Effect of iron supplementation on fatigue in nonanemic menstruating women with low ferritin: a randomized controlled trialPMIDVaucher P et al. · CMAJ · 2012
Fatigue decreased by 47.7% in iron group vs 28.8% in placebo (p=0.02) in 198 non-anaemic women with ferritin <50 ug/L
- 17Iron supplementation for unexplained fatigue in non-anaemic women: a double-blind randomised trialVaucher P, Druais PL, Waldvogel S et al. · BMJ · 2012
- 18Iron supplementation for unexplained fatigue in non-anaemic women: double blind randomised placebo controlled trialPMIDVerdon F et al. · BMJ · 2003
Fatigue decreased 29% in iron group vs 13% in placebo (p=0.004); benefit restricted to women with ferritin <=50 ug/L
Reviews & position papers
1- 19Oral iron supplementation for runners: effects on iron status and running performanceRubeor A, Goojha C, Manning J et al. · Sports Med · 2018
Reference material
2- 20Pengelly M, Pumpa K, Pyne DB et al.. Iron deficiency, supplementation, and sports performance in female athletes: A systematic review. Journal of sport and health science. 2025Source linkedPMID
- 21McCann S, Perapoch Amadó M, Moore SE. The Role of Iron in Brain Development: A Systematic Review. Nutrients. 2020Source linkedPMID
Common questions.
Quick answers about Iron, drawn from the data on this page.
What is Iron?
Essential for oxygen transport via hemoglobin, energy production, and immune function. Most common nutritional deficiency worldwide, especially in women.
What is Iron used for?
Commonly cited benefits of Iron include: Oxygen transport; Energy production; Immune function; Cognitive function; Athletic performance. NutriStack rates the overall evidence as strong.
What is a typical dose of Iron?
A typical adult dose of Iron is 18–45 mg daily (higher doses only under medical supervision for confirmed deficiency). The commonly recommended form is Iron bisglycinate (gentle, well-absorbed) or ferrous sulfate (standard). These are general ranges, not personalized advice; confirm the right dose with a clinician.
What are the side effects of Iron?
Reported side effects include constipation, nausea, dark stools, gi distress. This is educational information; check with a healthcare professional before use.
How strong is the evidence for Iron?
NutriStack rates this as Strong, meaning multiple high-quality meta-analyses or systematic reviews converge on the same finding. Full tier criteria are at https://nutristackapp.com/methodology/evidence-tiers.
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