Abstract
Iron is found in almost all foods, so dietary iron intake is related to energy intake. However, its availability for absorption is quite variable, and poor bioavailability is a major reason for the high prevalence of nutritional iron deficiency anaemia. Absorption occurs primarily in the proximal small intestine through mature enterocytes located at the tips of the duodenal villi. Two transporters: Hem Carrier Protein 1 (HCP1) and Divalent Metal Transporter 1 (DMT1) appear to mediate the entry of most if not all dietary iron into these mucosal cells. Absorption is regulated according to the body's needs. The results of studies suggest that iron absorption is regulated by the control of iron export from duodenal enterocytes to the circulating transferrin pool by ferroportin. Hepcidin, a 25-amino acid polypeptide, which is synthesised primarily in hepatocytes, reduces the iron absorption from the intestine by binding to the only known cellular iron exporter, ferroportin, causing it to be degraded. Therefore, hepcidin is now considered to be the most important factor controlling iron absorption.