Iron absorption from plant sources is poor because dietary non-heme iron is predominantly in the ferric form. Which vitamin directly facilitates duodenal non-heme iron absorption and by what action?

• A Vitamin A, by mobilizing stored ferritin from enterocytes
• B Vitamin E, by preventing oxidative precipitation of iron in the lumen
• C Vitamin D, by inducing calbindin-mediated iron transport
• D Vitamin C, by reducing ferric iron to the ferrous form in the intestinal lumen ✓

Explanation

Duodenal divalent metal transporter 1 transports only ferrous iron across the brush border. Ascorbic acid reduces luminal Fe3+ to Fe2+, forming a soluble chelate that remains absorbable, which is why citrus juice markedly increases non-heme iron uptake. Calbindin mediates calcium transport under vitamin B control, not iron transport, and neither vitamin A nor vitamin E participates in the reduction step. This interaction is the basis for advising iron supplements with vitamin C-rich foods in iron deficiency anemia.

Reference: Harper's Illustrated Biochemistry, 32nd ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.