Concurrent Administration of Iron Polysaccharide Complex and Magnesium Glycinate
Iron polysaccharide complex and magnesium glycinate should be separated by at least 2 hours to avoid significant reduction in iron absorption, as magnesium can chelate with iron and substantially impair its bioavailability.
Mechanism of Interaction
Iron supplements form stable complexes (chelation) with various compounds, including magnesium, which is the primary mechanism causing decreased iron bioavailability 1. While magnesium glycinate is a different formulation than magnesium oxide, the fundamental interaction between magnesium and iron remains clinically relevant across magnesium formulations 2.
Clinical Evidence of Magnesium-Iron Interaction
A case report documented refractory iron deficiency anemia in a patient taking oral iron supplements concurrently with magnesium laxatives, where the anemia only improved after stopping magnesium overuse and switching to intravenous iron 2.
When the patient resumed magnesium laxative use, hemoglobin levels suddenly decreased again, demonstrating the clinical significance of this interaction 2.
The case report specifically concluded that clinicians should be attentive to interactions between iron and magnesium products 2.
Practical Administration Guidelines
Separate iron and magnesium by at least 2 hours to minimize chelation and maximize iron absorption 3, 1:
Take iron polysaccharide at least 1 hour before or 2 hours after magnesium glycinate 3.
Avoid taking iron with other chelating substances including calcium-containing foods, tea, or coffee 3.
Consider taking iron on an empty stomach for optimal absorption, though this may increase gastrointestinal side effects 4.
Alternative Strategies if Separation is Impractical
If maintaining a 2-hour separation proves difficult in practice:
Consider once-daily dosing of iron at bedtime to reduce awareness of gastrointestinal effects and simplify the medication schedule 4.
Take magnesium glycinate at a different time of day (e.g., morning if iron is taken at night) 4.
Monitor hemoglobin response within 2 weeks and ferritin within 1 month to ensure adequate iron absorption is occurring 3.
Important Caveats
Iron polysaccharide complex offers no tolerability advantage over other iron salts and may actually be less effective than ferrous formulations 4, 5.
A comparative study showed iron polysaccharide was associated with the smallest rise in hematocrit among four oral iron preparations 3.
If anemia fails to improve despite adherence, consider switching to intravenous iron rather than continuing oral supplementation, as IV iron bypasses absorption issues entirely 4.