Iron absorption primarily occurs in the duodenum of the small intestine. Dietary iron exists in two forms: heme iron and non-heme iron. Heme iron, found in animal products, is more readily absorbed than non-heme iron, which is present in plant-based foods. The absorption process involves several steps:
Reduction: Non-heme iron (Fe3+) must be reduced to its ferrous form (Fe2+) by ferric reductase on the enterocyte surface. Transport: Fe2+ is transported into enterocytes via the DMT1 (divalent metal transporter 1). Storage and Export: Inside enterocytes, iron can be stored as ferritin or exported into the bloodstream via ferroportin. Hepcidin, a liver-produced hormone, regulates ferroportin activity.
