Elemental Iron Content in Ferrous Bisglycinate
Ferrous bisglycinate contains 25 mg of elemental iron per tablet according to the most recent clinical practice guidelines. 1
Understanding Elemental Iron in Iron Supplements
Iron supplements are available in various formulations, each containing different amounts of elemental iron. The elemental iron content is the actual amount of iron available for absorption by the body, which is what matters clinically for treating or preventing iron deficiency anemia.
Comparison of Elemental Iron Content in Different Iron Formulations:
| Iron Formulation | Elemental Iron Content |
|---|---|
| Ferrous bisglycinate | 25 mg per tablet |
| Ferrous sulfate | 65 mg per tablet |
| Ferrous gluconate | 27-38 mg per tablet |
| Ferrous fumarate | 106-150 mg per tablet |
| Polysaccharide-iron complex | Varies (listed in product name) |
Clinical Implications
When prescribing ferrous bisglycinate for iron deficiency anemia, it's important to consider that it contains less elemental iron per tablet than ferrous sulfate or ferrous fumarate. However, several studies suggest it may have better absorption characteristics:
- Ferrous bisglycinate appears to have higher bioavailability than other iron salts, potentially making the lower elemental iron content clinically effective 2
- It may cause fewer gastrointestinal side effects compared to traditional iron salts 3, 4
Dosing Considerations
For treating iron deficiency anemia:
- Despite the lower elemental iron content, ferrous bisglycinate may be as effective as higher doses of other iron formulations
- In pregnancy, 25 mg of elemental iron from ferrous bisglycinate has been shown to be as effective as 50 mg of elemental iron from ferrous sulfate 4
Potential Advantages of Ferrous Bisglycinate
- Better gastrointestinal tolerability profile compared to ferrous sulfate and ferrous fumarate 3
- Lower frequency of black stools (8% with ferrous bisglycinate vs. 22% with ferrous fumarate and 31% with ferrous sulfate) 3
- May be particularly useful for patients who experience GI side effects with conventional iron formulations
Important Clinical Caveat
When monitoring response to iron therapy, remember that:
- Hemoglobin should increase by 1 g/dL within 2 weeks of supplementation
- Ferritin should increase within a month in adherent patients
- If these parameters are not met, consider switching to IV iron 1
While ferrous bisglycinate may be better tolerated, it's important to recognize that the 25 mg elemental iron content is lower than traditional ferrous sulfate (65 mg), which may necessitate different dosing strategies in certain clinical scenarios.