Form Comparison

Heme Iron Polypeptide vs Iron Bisglycinate

How heme iron polypeptide and iron bisglycinate differ in elemental content, absorption, tolerance, and cost.

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Quick verdict. Both are the gentle options when iron salts fail. Bisglycinate is cheaper, vegetarian, and delivers enough iron (25-50 mg) to replete a deficiency; heme iron polypeptide carries little iron per tablet but is barely affected by meals, tea, or calcium. Choose bisglycinate for repletion and heme iron for low-dose maintenance when you cannot time iron away from food.

Side by Side

Heme Iron Polypeptide Iron Bisglycinate
Elemental content Varies by product 20% elemental iron
Absorption High High
How it is absorbed Iron bound in the heme ring, absorbed intact through a separate heme pathway. Absorption is much less affected by phytates, calcium, and tea than non-heme iron. Iron chelated to two glycine molecules. The chelate is less affected by dietary phytates than iron salts, and absorption remains regulated by iron status.
Typical dose Product-specific; per-tablet iron is low 25-50 mg elemental iron daily
Common uses GI intolerance to iron salts, maintenance after repletion iron deficiency with GI intolerance to salts, pregnancy
Side effects Low GI side effect rate at the low doses used. Typically fewer GI complaints than ferrous sulfate in trials, partly due to lower doses.
Cost High Moderate
Also called heme iron, HIP ferrous bisglycinate chelate, Ferrochel, gentle iron

When to Choose Heme Iron Polypeptide

Choose heme iron polypeptide when you need iron that is less affected by meals and tolerate only low doses. Derived from animal hemoglobin; not vegetarian.

Heme Iron Polypeptide

Choose heme iron polypeptide when you need iron that is less affected by meals and tolerate only low doses.

What to look for: Heme Iron Polypeptide named on the Supplement Facts panel, with the amount per serving stated.

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When to Choose Iron Bisglycinate

Choose iron bisglycinate when ferrous salts cause GI side effects. Often the switch when sulfate causes constipation or nausea.

Iron Bisglycinate

Easier on the stomach for many people. Fewer head-to-head data than sulfate.

What to look for: Elemental iron stated per capsule, often 25-36 mg. Ferrochel is the most studied raw material.

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Products on Titrate

15,991 of the 214,745 labels in the NIH Dietary Supplement Label Database list iron as an active ingredient (8,640 on market). 1,146 are sold as iron products by name.

Open supplement search

Iron does not have its own search category yet. Each product above links to its full label in the NIH database.

Related

References

NIH Office of Dietary Supplements. Iron: Fact Sheet for Health Professionals.

Hallberg L, Brune M, Rossander L. Iron absorption in man: ascorbic acid and dose-dependent inhibition by phytate. Am J Clin Nutr. 1989;49(1):140-144.

Moretti D, et al. Oral iron supplements increase hepcidin and decrease iron absorption from daily or twice-daily doses in iron-depleted young women. Blood. 2015;126(17):1981-1989.

Tolkien Z, et al. Ferrous sulfate supplementation causes significant gastrointestinal side-effects in adults: a systematic review and meta-analysis. PLoS One. 2015;10(2):e0117383.

Stoffel NU, et al. Iron absorption from oral iron supplements given on consecutive versus alternate days and as single morning doses versus twice-daily split dosing in iron-depleted women: two open-label, randomised controlled trials. Lancet Haematol. 2017;4(11):e524-e533.

Stoffel NU, et al. Iron absorption from supplements is greater with alternate day than with consecutive day dosing in iron-deficient anemic women. Haematologica. 2020;105(5):1232-1239.

World Health Organization. WHO guideline on use of ferritin concentrations to assess iron status in individuals and populations. Geneva: WHO; 2020.