How much elemental iron is in a 28 mg dose of ferrous bisglycinate?

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Last updated: October 29, 2026 • View editorial policy

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Elemental Iron Content in Ferrous Bisglycinate

A 28 mg dose of ferrous bisglycinate contains approximately 25 mg of elemental iron 1.

Direct Answer from Guidelines

According to the 2024 AGA Clinical Practice Update on Management of Iron Deficiency Anemia, ferrous bisglycinate tablets contain 25 mg of elemental iron per tablet 1. Your 28 mg dose would therefore deliver approximately 25 mg of elemental iron, as the standard formulation listed in the guideline table shows 25 mg elemental iron content per tablet.

Important Context

The molecular weight ratio of ferrous bisglycinate means that approximately 89% of the total compound weight is elemental iron (25 mg elemental iron from a typical ~28 mg ferrous bisglycinate tablet). This is a significantly higher percentage of elemental iron compared to:

  • Ferrous sulfate: 65 mg elemental iron per tablet (approximately 20% elemental iron by weight)
  • Ferrous gluconate: 27-38 mg elemental iron per tablet (approximately 12% elemental iron by weight)
  • Ferrous fumarate: 106-150 mg elemental iron per tablet (approximately 33% elemental iron by weight) 1

Clinical Relevance

Ferrous bisglycinate is better tolerated than conventional iron salts while providing effective iron repletion 2, 3. Recent studies demonstrate that 25-30 mg elemental iron as ferrous bisglycinate daily effectively corrects iron deficiency with significantly fewer gastrointestinal side effects compared to higher doses of ferrous sulfate 2, 4, 3.

The 25 mg elemental iron dose from your 28 mg ferrous bisglycinate formulation represents a low-dose, well-tolerated option that can successfully prevent and treat iron deficiency while minimizing adverse effects like nausea, constipation, and abdominal pain 3.

References

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