Iron is absorbed in what form, and what maintains that form during absorption?

• A. Ferrous State; Gastric Acid Maintains Ferrous State
• B. Ferric State; Ferric Is Insoluble and Not Absorbed
• C. Ferrous State; Gastric Acid Inhibits Ferrous Absorption
• D. Ferric State; Pancreatic Enzymes Convert Ferric to Ferrous

Answer: (A)

Iron is absorbed best when it is in the ferrous (Fe2+) form. The stomach’s acidic environment keeps iron soluble and reduces ferric iron (Fe3+) to Fe2+, so it can be taken up in the duodenum by the DMT1 transporter. If gastric acidity is low, iron tends to stay ferric and precipitate as insoluble compounds, which decreases absorption. The reduction to Fe2+ happens in the upper intestine rather than by pancreatic enzymes, so maintaining the ferrous state with gastric acid is what enables efficient absorption.