Iron (Ferrous Bisglycinate)
Also known as: ferrous glycinate, iron bisglycinate, iron amino‑acid chelate
Randomized trials and a meta‑analysis show ferrous bisglycinate can increase haemoglobin and iron markers in iron‑deficient and pregnant populations; a 2023 meta‑analysis found higher haemoglobin and fewer gastrointestinal events with ferrous bisglycinate versus other iron supplements among pregnant women. Individual RCTs report better absorption and tolerability versus ferrous fumarate or ferrous sulphate at lower elemental iron doses, while one trial found 18 mg ferrous bisglycinate was less effective than 60 mg ferrous sulfate for raising ferritin in a mostly iron‑replete population.
Last reviewed: 2026-10-14 · 5 indexed studies
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Overview
Ferrous bisglycinate is an iron amino‑acid chelate used orally to prevent or treat iron deficiency. Compared with standard iron salts it is reported in trials to have similar or improved effects on haemoglobin and ferritin at lower elemental iron doses and to be associated with fewer gastrointestinal adverse events in some populations.
Mechanism & Function
Mechanism of Action
Ferrous bisglycinate is an iron atom chelated to glycine residues; the chelate is proposed to protect iron from inhibitors in the gut lumen and improve intestinal uptake, increasing systemic iron availability for haemoglobin synthesis and ferritin storage. Trials report higher post‑dose serum iron and greater increases in haematological markers versus some iron salts, consistent with improved bioavailability.
Physiological Role
Provides absorbable elemental iron for erythropoiesis and replenishment of iron stores.
Primary Pathways
Performance / Health Relevance
By raising haemoglobin and ferritin, ferrous bisglycinate may improve outcomes related to iron deficiency such as fatigue and maternal anaemia; evidence pertains to correction of iron‑status biomarkers rather than direct measures of physical performance in the provided abstracts.
Evidence Review
Practical Use & Dosage
- Minimum Effective Dose
- Evidence of efficacy reported with ~18 mg elemental iron (as ferrous bisglycinate) in some contexts, and with 24 mg elemental iron in pregnant women.
- Optimal Range
- Studies used a range from fortified food providing ~2.5–5 mg/day up to supplement doses of 18–25 mg elemental iron; comparative trials used much higher elemental doses for iron salts (40–66 mg).
- Upper / Caution Level
- Not established for ferrous bisglycinate specifically; one study found 80 mg elemental iron (as fumarate) was associated with more constipation versus lower doses. General caution with high iron doses and risk of gastrointestinal side effects or iron overload.
- Timing
- Taken orally; some trials measured absorption after single doses (fasted serum iron at 1–2 h). Specific timing relative to meals varied by trial.
- Best Format
- Oral capsules/tablets or as a food fortificant; some trials combined ferrous bisglycinate with folinic acid and multivitamins.
- Bioavailability
- Clinical trials report higher post‑dose serum iron and numerically larger increases in haematological markers compared with some iron salts at lower elemental iron doses, consistent with better bioavailability.
- Absorption Considerations
- Chelated form may be less affected by dietary inhibitors compared with non‑chelated iron salts according to the trials showing improved absorption.
Safety & Interactions
Side Effects
- •Gastrointestinal complaints (nausea, abdominal pain, bloating, constipation, metallic taste)
- •Black stools (dose dependent, less frequent with ferrous bisglycinate in some trials)
Contraindications
- Known iron overload disorders (eg, haemochromatosis)
- Known hypersensitivity to ingredient or excipients
Who Should Avoid
- •Individuals with diagnosed iron overload
- •People already receiving high‑dose iron therapy without medical supervision
Monitoring
Monitor haemoglobin and ferritin during therapy to assess response and avoid iron excess; consider clinical guidance for iron supplementation in pregnancy and other populations.
Frequently Asked Questions
Auto-generated from indexed evidence — dosage, safety, interactions, and more.
When is Iron (Ferrous Bisglycinate) typically used or indicated?
Iron (Ferrous Bisglycinate) is most commonly used for: Prevention and treatment of iron deficiency and iron‑deficiency anaemia, Iron fortification of foods, Prenatal iron supplementation. Provides absorbable elemental iron for erythropoiesis and replenishment of iron stores.
How does Iron (Ferrous Bisglycinate) work?
Ferrous bisglycinate is an iron atom chelated to glycine residues; the chelate is proposed to protect iron from inhibitors in the gut lumen and improve intestinal uptake, increasing systemic iron availability for haemoglobin synthesis and ferritin storage. Trials report higher post‑dose serum iron and greater increases in haematological markers versus some iron salts, consistent with improved bioavailability.
What is the recommended dose of Iron (Ferrous Bisglycinate)?
The optimal range is Studies used a range from fortified food providing ~2.5–5 mg/day up to supplement doses of 18–25 mg elemental iron; comparative trials used much higher elemental doses for iron salts (40–66 mg).. with a minimum effective dose of Evidence of efficacy reported with ~18 mg elemental iron (as ferrous bisglycinate) in some contexts, and with 24 mg elemental iron in pregnant women.. Best taken: Taken orally; some trials measured absorption after single doses (fasted serum iron at 1–2 h). Specific timing relative to meals varied by trial.. Upper / caution level: Not established for ferrous bisglycinate specifically; one study found 80 mg elemental iron (as fumarate) was associated with more constipation versus lower doses. General caution with high iron doses and risk of gastrointestinal side effects or iron overload..
What are the side effects of Iron (Ferrous Bisglycinate)?
Reported side effects include: Gastrointestinal complaints (nausea, abdominal pain, bloating, constipation, metallic taste); and Black stools (dose dependent, less frequent with ferrous bisglycinate in some trials). Monitoring: Monitor haemoglobin and ferritin during therapy to assess response and avoid iron excess; consider clinical guidance for iron supplementation in pregnancy and other populations.
Who should avoid Iron (Ferrous Bisglycinate)?
Iron (Ferrous Bisglycinate) is generally not recommended for: Individuals with diagnosed iron overload; People already receiving high‑dose iron therapy without medical supervision; Known iron overload disorders (eg, haemochromatosis); and Known hypersensitivity to ingredient or excipients.
How strong is the evidence for Iron (Ferrous Bisglycinate)?
Evidence level: Moderate (overall score 67/100), based on 5 indexed studies on SuppIndex.
Research & References (5)
The effects of oral ferrous bisglycinate supplementation on hemoglobin and ferritin concentrations in adults and children: a systematic review and meta-analysis of randomized controlled trials.
Systematic review and meta‑analysis of 17 RCTs comparing ferrous bisglycinate with other iron supplements. Meta‑analyses in pregnant women (n trials = 9) and children (n trials = 4) examined haemoglobin, ferritin and gastrointestinal adverse events.
Efficacy and Safety of Ferrous Bisglycinate and Folinic Acid in the Control of Iron Deficiency in Pregnant Women: A Randomized, Controlled Trial.
Randomized controlled trial in pregnant women (12–16 weeks gestation) comparing ferrous bisglycinate (24 mg elemental iron, with folinic acid and multivitamins) to ferrous fumarate (66 mg elemental iron).
Low-Dose Prophylactic Oral Iron Supplementation (Ferrous Fumarate, Ferrous Bisglycinate, and Ferrous Sulphate) in Pregnancy Is Not Associated With Clinically Significant Gastrointestinal Complaints: Results From Two Randomized Studies.
Two randomized, double‑blind studies in pregnant women comparing low‑dose iron formulas in equipotent doses including ferrous bisglycinate (25 mg elemental) versus ferrous fumarate and ferrous sulphate.
The efficacy of ferrous bisglycinate and electrolytic iron as fortificants in bread in iron-deficient school children.
Randomized trial of ferrous bisglycinate used as a bread fortificant versus electrolytic iron in iron‑deficient school children (6–11 years).
Is a Lower Dose of More Bioavailable Iron (18-mg Ferrous Bisglycinate) Noninferior to 60-mg Ferrous Sulfate in Increasing Ferritin Concentrations While Reducing Gut Inflammation and Enteropathogen Detection in Cambodian Women? A Randomized Controlled Noninferiority Trial.
Double‑blind randomized non‑inferiority trial in non‑pregnant Cambodian women comparing 60 mg ferrous sulfate, 18 mg ferrous bisglycinate, and placebo for 12 weeks, with assessment of ferritin, fecal calprotectin and enteropathogen detection.
Related Ingredients
Other top-rated ingredients in Minerals.
Magnesium Glycinate
84/100An amino acid chelate of magnesium providing elemental Mg²⁺ bound to two glycine molecules, offering superior bioavailability and minimal gastrointestinal side effects.
Calcium Citrate
75/100Calcium bound to citric acid; ~24% elemental Ca by mass; absorbed across the small intestine via active transport and paracellular diffusion regardless of gastric pH.
Zinc
74/100Systematic reviews and meta-analyses of human trials show that oral zinc supplementation reduces duration and increases recovery rates in acute and persistent watery diarrhoea in children; lowers inflammatory lesion counts in acne; reduces pain severity in primary dysmenorrhea; and in small trials (20–30 mg/day) improved fasting glucose and 2‑hr OGTT in people with prediabetes. Adverse effects reported include increased vomiting in children receiving zinc for diarrhoea.
Research Overview
Moderate EvidenceCite this ingredient
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Stable URL
https://thesuppindex.com/ingredients/iron-ferrous-bisglycinate
SuppIndex. (2026). Iron (Ferrous Bisglycinate): Evidence summary, dosage and clinical studies. Retrieved October 16, 2026, from https://thesuppindex.com/ingredients/iron-ferrous-bisglycinate
Based on 5 indexed studies · Evidence level: Moderate.
Goal Ratings
Stack Compatibility
Often combined with folinic acid and multivitamins in trials; compatibility with other oral nutrients is commonly acceptable but timing with calcium and some minerals can affect absorption.