Iron is absorbed in which region of the small intestine?

• A. Ileum
• B. Duodenum and Proximal Jejunum
• C. Stomach
• D. Large Intestine

Answer: (B)

Iron absorption takes place mainly in the upper part of the small intestine—the duodenum and the proximal jejunum. In these regions, iron from the diet is first converted to the ferrous form and then transported into enterocytes by the transporter DMT1. Inside the cells, iron can be stored as ferritin or exported into the bloodstream through ferroportin, where it’s converted to ferric form by hephaestin and then bound by transferrin in the blood. The process is tightly regulated by hepcidin, which lowers iron absorption when stores are high by reducing ferroportin on the basolateral side, and increases absorption when iron is needed.

Stomach and large intestine do not serve as major sites for iron absorption, and while some iron handling may occur elsewhere, the primary and most efficient region for absorbing dietary iron is the duodenum and proximal jejunum.