The essentiality of the microminerals iron is due to its presence in heme, a molecule crucial to energy transformation and therefore crucial to life itself. The atom of iron in the center of the heme molecule allows the transport of oxygen to tissues (hemoglobin); the transitional storage of oxygen in tissues, particularly cardiac muscle (myoglobin); and the transport of electrons through the respiratory chain (cytochromes).
Iron has several oxidation states, depending on its chemical environment. The only states that are stable in the aqueous environment of the human body (and food) are the ferric form and the ferrous. Nevertheless, the iron atom in the center of heme is highly reactive and allows the formation of coordinate bonds with six other atoms.
Although most of the body’s iron is found as a component of heme, some of the mineral is found in storage form, and some is associated with certain nonheme enzymes.In adult, functional components, hemoglobin comprises about 85%; myoglobin approximately 10%; the enzymes approximately 1%. The total amount of iron found in person is related not only to body weight but also is influenced by a variety of physiologic conditions, including age, sex, pregnancy, and state of growth. For example, the amount of iron stored in the premenopausal woman is likely to be much less than in the postmenopausal female or in the male.
Iron in Human Body
