Although iron is the most abundant heavy metal in the earth’s crust, iron deficiency ranks as a major nutritional problem worldwide. Absorption of iron is controlled strictly, and excretion of iron is limited. Protein is one of the major participants in the tight regulation of iron: bioavailability of dietary iron is influenced by concomitantly ingested proteins; dietary pat­ terns and protein status affect iron status; additionally, specialized pro­ teins are instrumental in iron absorption and transport.