Ferrous Gluconate vs Iron Bisglycinate
How ferrous gluconate and iron bisglycinate differ in elemental content, absorption, tolerance, and cost.
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Side by Side
| Ferrous Gluconate | Iron Bisglycinate | |
|---|---|---|
| Elemental content | 12% elemental iron | 20% elemental iron |
| Absorption | High | High |
| How it is absorbed | Ferrous iron absorbed by DMT1, as with sulfate. | 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 | 27-38 mg elemental iron per tablet | 25-50 mg elemental iron daily |
| Common uses | iron deficiency, lower per-tablet dose | iron deficiency with GI intolerance to salts, pregnancy |
| Side effects | Similar to sulfate per mg of elemental iron; fewer side effects per tablet only because each tablet holds less iron. | Typically fewer GI complaints than ferrous sulfate in trials, partly due to lower doses. |
| Cost | Low | Moderate |
| Also called | iron gluconate | ferrous bisglycinate chelate, Ferrochel, gentle iron |
| Labels in index | 67 | 283 |
When to Choose Ferrous Gluconate
Choose ferrous gluconate when you want smaller per-tablet iron doses. Lowest elemental percentage of the common ferrous salts.
Ferrous Gluconate
Choose ferrous gluconate when you want smaller per-tablet iron doses.
What to look for: Ferrous Gluconate named on the Supplement Facts panel, with the amount per serving stated.
Find on iHerb Affiliate linkWhen 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.
Find on iHerb Affiliate linkProducts on Titrate
In Titrate's index of NIH label data, 67 labels named as iron products list ferrous gluconate and 283 list iron bisglycinate.
Iron does not have its own search category yet. Each product above links to its full label in the NIH database.
Related
- Iron supplement guide
- Iron Absorption Estimator
- Supplement Timing Optimizer
- Ferrous Sulfate vs Iron Bisglycinate
- Carbonyl Iron vs Iron Bisglycinate
- Ferrous Fumarate vs Iron Bisglycinate
- Ferrous Gluconate vs Ferrous Sulfate
- Heme Iron Polypeptide vs Iron Bisglycinate
- Ferrous Fumarate vs Ferrous Gluconate
- All form comparisons
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.