Iron is used for prenatal and multivitamin supplementation, and for the treatment of iron-deficiency anemia. Iron Metabolism Total body iron normally does not exceed 5 to 6 grams. Iron is necessary for production of red blood cells, for oxygenation of hemoglobin and myoglobin, and for the function of certain cytochromes and enzyme cofactor catalysts. Excessive amounts of unbound iron produce systemic toxicity. Iron needs are met solely through intestinal absorption, either as the organic, preformed heme moiety found in red meats, or as the inorganic form such as that found in iron supplements or iron-fortified foods.
Ferrous iron is absorbed in the duodenum and upper jejunum.
If released to transferrin, specific target organs with transferrin receptors will ultimately bind the molecule and utilize ferric ion. Iron confined to mucosal cell ferritin will be eliminated from the body when the intestinal cell dies. This intestinal cell turnover is the primary mode of excess iron elimination. With ingestion of excessive amounts of iron, the normal intestinal storage capacity is exceeded. This produces excess free iron in the intestinal cell itself, as well as increased levels presented to plasma.