Dietary non-heme iron is absorbed at the duodenal brush border only after reduction to which chemical form?

• A Ferric iron (Fe3+)
• B Ferrous iron (Fe2+) ✓
• C Iron bound to transferrin
• D Heme iron chelated to protoporphyrin

Explanation

Duodenal DMT1 (divalent metal transporter 1) transports only divalent cations, so dietary ferric Fe3+ must first be reduced to ferrous Fe2+ by brush border ferric reductases such as DCYTB. Vitamin C enhances absorption by maintaining iron in the reduced state, while phytates and tannins inhibit it. Transferrin-bound iron enters cells via endocytosis in plasma, not across the gut lumen, and heme iron follows a separate pathway independent of DMT1.

Reference: Guyton and Hall Textbook of Medical Physiology, 14th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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