Figure 1.

Iron absorption metabolism. Non-heme iron is ultimately taken up from the lumen by divalent metal transporter (DMT-1) on the microvillus membrane, before joining the labile iron pool in the cell. Ferric iron has to be reduced to the ferrous form by duodenal cytochrome b (Dcytb) before the uptake. Ferrous iron in the labile iron pool is then transferred to the circulation by ferroportin (FPN), which requires hephaestin for oxidation to the ferric form to bind transferrin. Heme iron is taken up by a specific receptor. Internalized heme iron is degraded by heme-oxygenase, releasing non-heme iron. The non-heme iron is then transported to the cytoplasm, joining the labile iron pool and is then transferred to the bloodstream by FPN in the same manner as non-heme iron.