Evidence overview
Iron
Iron supplementation is one of the most clinically established interventions in nutrition, with strong evidence in specific at-risk populations: pregnant women, infants and toddlers, menstruating women with heavy bleeding, vegetarians and vegans, and people with absorption disorders. For people with adequate iron status, supplementation is not recommended and can cause adverse effects. Iron is one of the clearest cases where personalized framing matters more than population-level summary.
Most studied for
Coverage pending
PubMed coverage
Coverage pending
Safety profile
In your full report
Mechanism class
Essential mineral required for hemoglobin synthesis (oxygen transport in red blood cells), myoglobin (oxygen...
Study coverage
Study coverage by goal
PubMed counts for Iron grouped by the goal each study targets.
Evidence overview is temporarily unavailable for Iron.
Evidence
What the evidence covers
The terrain of the published literature, not its conclusions.
Iron is one of the most-studied minerals in supplementation research, and the literature divides cleanly into two questions with very different evidence shapes: treating iron deficiency in at-risk populations (where evidence is overwhelmingly positive and clinical consensus is clear) and routine supplementation in healthy adults with adequate intake (where evidence is limited and supplementation is not generally recommended). Supplemental forms vary substantially in bioavailability and gastrointestinal tolerability: ferrous sulfate is the historical standard and most-studied form; ferrous gluconate, fumarate, and iron bisglycinate are alternatives used primarily to improve tolerability rather than absorption.
The outcome dimensions covered most heavily are pregnancy (the most-replicated supplementation context; trials consistently show benefit), infant and toddler iron requirements (where breast milk alone becomes insufficient around 6 months of age), iron-deficiency anemia treatment in adolescent girls and menstruating women, supplementation in vegetarian and vegan diets (where non-heme dietary iron is less bioavailable), and supplementation in people with celiac disease, inflammatory bowel disease, or post-gastric-bypass (where absorption is impaired). Smaller research streams cover athletic performance (especially endurance, in iron-deficient or low-ferritin athletes) and cognitive function in iron-deficient populations.
Demographically, pregnant women dominate the largest body of supplementation evidence; pediatric populations dominate the prevention literature; older adults feature in the absorption-impairment literature. Dosing strategy is an active research area: the regulatory hormone hepcidin rises in response to daily oral iron, which is the mechanistic basis for ongoing research into alternate-day dosing strategies. Form choice (ferrous sulfate vs. iron bisglycinate vs. others) primarily affects gastrointestinal tolerability rather than efficacy in most contexts.
Safety
Safety summary
Common adverse events, drug interactions, and special populations.
Iron is well-tolerated in people with iron deficiency or low iron status. The most-common adverse effects of supplementation are gastrointestinal: constipation, nausea, abdominal discomfort, and dark stools, which improve with form selection (iron bisglycinate is typically better-tolerated) or alternate-day dosing. Acute iron toxicity is a serious safety concern: iron is among the leading causes of pediatric accidental poisoning deaths, and household iron supplements should be stored well out of reach of children. Long-term iron overload (hemochromatosis, repeated transfusions, certain genetic conditions) can cause organ damage, which is why routine supplementation in people with adequate iron status is not recommended. Drug interactions include reduced absorption of levothyroxine, quinolones, tetracyclines, bisphosphonates, and proton pump inhibitors (which reduce iron absorption). People with hemochromatosis, hereditary iron overload, or recent gastric surgery should not supplement without medical supervision.
This summary is informational and not medical advice. Consult a clinician before starting or changing any supplement, especially if you take prescription medications.
Foundations
Foundation of the evidence base
A few studies the field anchors on. Not the full picture, just the starting points.
Most recent practice update from the American Gastroenterological Association on managing iron deficiency anemia - the primary indication for iron supplementation. Provides the field's current expert-consensus framework for diagnosis, supplementation strategy, and when to escalate beyond oral iron.
View on PubMedMost recent Cochrane synthesis on daily oral iron supplementation during pregnancy - the most-replicated and clinically-established use of iron supplementation, relevant to tens of millions of pregnancies globally each year.
View on PubMedFoundational position paper from the European pediatric gastroenterology and nutrition society on iron requirements in infants and toddlers, the second-largest at-risk population for iron deficiency globally and the clinical reference for pediatric iron supplementation.
View on PubMed
Limitations
What this page doesn't answer
Where the public summary stops and the personalized report begins.
This page summarizes the iron literature at a general level. It does not address whether you have a true iron deficiency or low iron status (which requires blood tests including ferritin and complete blood count), what dose and form are right for your specific situation, whether alternate-day dosing is appropriate for your case, or how iron interacts with your other medications and supplements. Iron is the most clear case where supplementation is highly beneficial for some populations and potentially harmful for others - lab testing and personalized framing are essential rather than optional.
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