Which transporter is primarily responsible for heme iron absorption in the intestine?

• A. DMT1
• B. Heme transporter
• C. Heme carrier protein 1
• D. Ferroportin

Answer: (B)

The key idea is that heme iron uses a specialized apical transporter on the intestinal lining to enter the enterocyte. This transporter is Heme Carrier Protein 1, which binds and moves intact heme into the cell. Inside the enterocyte, heme is broken down by heme oxygenase to release iron, which then joins the intracellular iron pool and can be exported into the bloodstream by ferroportin. This pathway is distinct from non-heme iron absorption, which relies on DMT1 to bring Fe2+ across the brush border after reduction. So the precise transporter for heme uptake is Heme Carrier Protein 1, with ferroportin handling export and DMT1 handling non-heme iron uptake.