Supplement evidence

057 / 575Mineral form

Ferrous sulfate

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The short answer

A standard oral treatment for confirmed iron deficiency and iron-deficiency anemia.

Evidence and scope: Established for an indicated use
This status does not grade the ingredient for every goal, outcome, or person.
Important limitation: The benefit is tied to the stated indication, dose, and population; it is not evidence of broader disease prevention or longer life.
Before deciding: Key concern: Separate calcium, antacids, thyroid medicine, and certain antibiotics; overdose is dangerous.

01 / PRACTICAL GUIDE

Dose, absorption, and combinations

These are indication-specific reference or studied ranges—not a personalized prescription. Start with the objective, then check the form, label, medicines, and health conditions.

Reference range by objective

Confirmed deficiencyOften 40–65 mg elemental iron once daily or every other day; clinician-directed

Reference or studied range—not a personalized prescription. The product label or a clinician may specify a different dose.

Dose source ↗

More is not automatically better. A clinician or product label may specify a different amount.

Absorption / solubilityWater-soluble

Water-soluble or readily water-dispersible. This does not mean excess is always harmless.

How it is commonly taken

Absorbs best away from food with vitamin C, but food may improve tolerance.

Do not combine casually

Separate calcium, antacids, thyroid medicine, and certain antibiotics; overdose is dangerous.

Dose and use source ↗

Dose and use links lead to primary or official source material. Search links are discovery tools, not proof that every returned paper applies.

02 / EVIDENCE

What the research says

We keep supportive, mixed, negative, safety, and contextual findings together. The headline never replaces the underlying papers.

4research papers in this ledger

4unique primary studies represented

841unique participants represented

These are audited counts for this JIVANA collection, not search-result totals. Participants are counted once when multiple papers use the same cohort; review papers are not added again to participant totals.

Open the research timelineResearch timeline

Entries are ordered by publication year. A study period appears only when the source reports it.

2023

Mixed or qualifiedPMID 36725875 · CTRI/2019/01/017169

Alternate day versus daily oral iron for treatment of iron deficiency anemia

Hemoglobin rose in both groups without a statistically significant difference (+1.05 versus +1.36 g/dL; p=0.47), and secondary outcomes also did not differ. Alternate-day dosing was not clinically superior in this trial.

Published: 2023Duration: 8 weeksn=200 participants

Study design and methods

Design: Double-blind randomized active-control trial
Population: 200 adults with iron-deficiency anemia and hemoglobin 10 g/dL or lower
Intervention: Ferrous sulfate providing 120 mg elemental iron on alternate days or 60 mg daily
Outcome: Hemoglobin change at 8 weeks and secondary hematologic outcomes

Open research record ↗

2023

Mixed or qualifiedPMID 38021373 · NCT05105438

Alternate day versus consecutive day oral iron supplementation in iron-depleted women

Ferritin was similar at equal total doses. Alternate-day dosing caused fewer gastrointestinal symptoms and lower hepcidin and had less iron deficiency at 6 months, but it took twice as long to deliver the same iron amount.

Published: 2023Duration: 180 daysn=150 participants

Study design and methods

Design: Randomized, double-masked, placebo-controlled dosing trial
Population: 150 young women with ferritin 30 µg/L or lower
Intervention: 100 mg oral iron on consecutive days for 90 days or on alternate days for 180 days, with placebo on non-iron days
Outcome: Ferritin at equal total dose, gastrointestinal symptoms, iron deficiency, and hepcidin

Funding or conflict note: Funded by the Swiss National Science Foundation; the authors declared no competing interests.

Open research record ↗

2020

Mixed or qualifiedPMID 31811360 · CTRI/2018/07/015106

Twice-daily versus alternate-day oral iron therapy in iron-deficiency anemia

Twice-daily dosing produced a faster hemoglobin rise, while alternate-day dosing produced a slower response with less nausea. The regimen choice involved a speed-versus-tolerability tradeoff rather than one schedule being universally best.

Published: 2020Duration: 6 weeksn=62 participants

Study design and methods

Design: Randomized active-control trial
Population: 62 patients with iron-deficiency anemia of varying severity
Intervention: 60 mg elemental iron twice daily or 120 mg on alternate days
Outcome: Time to a 2 g/dL hemoglobin rise and adverse effects

Open research record ↗

2006

Mixed or qualifiedPMID 16458655

Prophylactic iron in prenatal supplements and birth outcomes

Birth weight was 108 g higher and preterm birth was 8% versus 14%, but third-trimester iron status and small-for-gestational-age birth did not differ. Borderline, population-specific birth findings should not imply universal prophylaxis benefit.

Published: 2006Duration: From before 20 weeks to 26–29 weeks of gestationn=429 participants

Study design and methods

Design: Randomized placebo-controlled trial
Population: 429 initially iron-replete, nonanemic pregnant women from a low-income U.S. population
Intervention: Prenatal supplement with 30 mg iron as ferrous sulfate or no iron
Outcome: Third-trimester iron status, birth weight, preterm birth, and small-for-gestational-age birth

Open research record ↗

Unscreened discovery appendix—not evidence294 candidate publicationsSearch run: Aug 21, 2026

Complete for the displayed PubMed query at the search timestamp—not for all databases or every possible synonym. Candidates can be irrelevant, duplicate the same study, or report negative findings. They are never summed as evidence or participants until screened.

03 / SOURCES

Start with the source material

Official evidence overviewPubMed bounded human-evidence search Live PubMed discovery searchNational Library of Medicine

The live search is for discovery only. Search-result counts change and are not included in the audited totals above.

Recent PubMed discovery recordsDirect links to the first 12 records returned by the reproducible search. These are discovery candidates—not reviewed summaries or a count of supportive findings.

04 / EXPERT CONTEXT

Expert context—not evidence

Expert positions are dated context—not scientific evidence. They never raise the evidence status or become consensus by repetition.

No direct, source-verified endorsement is currently recorded. Research authorship or discussion alone is not treated as endorsement.