Iron in Summary

Humans contain about 2-4g iron of which most is in hemoglobin and to a lesser extent myoglobin. Iron from diet is found in heme (animal foods) and nonheme (plant foods) forms. The heme iron needs to be hydrolyzed where as the nonheme is enzymatically freed.

Heme iron is absorbed intact accross the brushborder of the enterocyte whereas nonheme iron is released as ferric in the stomach, which may be reduced to ferrous. The ferric is absorbed across brush border by binding to transporters and the ferrous facilitated by chelators and membrane proteins.Chelators inhibit or enhance absorption of iron. Absorption is also regulated by hepcidin and ferroportin. Other iron-absorption enhancers are sugars, acids, animal meat, and mucin. Other inhibitors are polyphenols, oxalates, phytates, phosvitin and some minerals.Iron is stored in the liver, bone marrow and spleen. Uptake into tissues depends on transferrin.

Iron needs depend on its loss such as through menstrual losses and dietary intake. Deficiency mainly can affect infants and children, teenagers, menstruating females and pregnant women (whose iron needs expand due to increased blood volume). Iron deficiency can develop gradually into anemia. Toxicity may occur due to taking too much iron in supplements or if one has a genetic disorder called hemochromatosis. In the case of hemochromatosis, which is most prevalent among caucasian males, a diet with limited meat intake may be necessary.

Published by David Despain, MS, CFS

David is a science and health writer living on Long Island, New York. He's written for a variety of publications including Scientific American, Outside Online, the American Society for Nutrition's (ASN) Nutrition Notes Daily, and Institute of Food Technologists' (IFT) Food Technology magazine and Live! blog. He's also covered new findings reported at scientific meetings including Experimental Biology, AAAS, AOCS, CASW, Sigma Xi, IFT, and others on his personal blog "Evolving Health." David is also an active member of organizations including the National Association of Science Writers (NASW), the American Association for the Advancement of Science (AAAS), the American Society for Nutrition, the Institute of Food Technologists, and the National Audubon Society. David has a master's degree in human nutrition from the University of Bridgeport, and a bachelor's degree in English from University of Illinois at Springfield. He also earned his Certified Food Scientist credential from the Institute of Food Technologists.

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