Hemoglobin—and therefore iron—really does give us our strength and the look of good health—our "rosy cheeks." One of the first symptoms of low iron is weakness, fatigue, or loss of stamina. Anemia results only after longer deficiency of iron or other nutrients; then, less hemoglobin and usually fewer red blood cells are made, and our ability to carry oxygen through the body is diminished. Iron and hemoglobin improve our respiratory activity. Many of the oxygen-dependent diseases (diseases that have symptoms based on circulation and the delivery of oxygen to tissues), such as coronary artery disease and vascular insufficiency, are worsened with iron deficiency. Many other symptoms, both psychological and physical, occur when we do not have enough iron. On the other hand, Jerome Sullivan, a researcher on iron metabolism, has recently shown that excess iron intake and storage may increase our risk of atherosclerosis and heart disease.

Iron is needed by some important enzymes for energy production and protein metabolism. The cytochrome system (a class of protein molecules that play a role in oxidative processes) depends on iron enzymes, which may work within the mitochondria (energy factories) of the cells to produce energy. The iron cytochromes, iron catalase, and iron peroxidase probably help protect our tissues and cells from oxidative damage, although most of the research in this area has been done on animals, and it is not clear yet whether the findings are analogous in humans, or if, in fact, iron can be an irritant to the vascular lining. Research is also being done on iron's role in the formation and health of tissue collagen and elastin and the involvement of iron in the immune system's health. When iron in the body is low, there seems to be an increased incidence of infections, possibly because of a decrease in lymphocyte proliferation and other white blood cells' ability to kill microorganisms. Iron also is helpful in the production of carnitine, a nonessential amino acid important for the oxidation and utilization of fatty acids.

Uses: Of course, the main use of iron is in the prevention and treatment of iron deficiency and iron deficiency anemia, whether caused by blood loss, pregnancy, or a low-iron diet. When total body iron or circulating iron is low, fatigue, learning difficulties, irritability, and other subtle symptoms may occur long before actual anemia is seen. Many emotional symptoms may occur in children as well.

Iron is used routinely during pregnancy and breastfeeding to prevent iron deficiency. Because of increased iron needs during these times, it is difficult to obtain all the required iron from the diet alone. The infant will usually get enough iron but will pull stores from the mother, who could become very depleted. Also, whenever there are menstrual periods with more than normal amounts of bleeding (medically called menorrhagia), iron is often suggested as a regular supplement. Iron has also been helpful in reducing pain in some women who have painful menstrual periods.

Sometimes fatigue, especially muscle fatigue and poor physical stamina, will respond to iron supplements. Subtle oxygen-deficit respiratory problems may be helped by attaining adequate iron levels, probably because the iron provides increased hemoglobin production and improved oxygenation of the tissue. There is some question as to whether iron acts as a mild antioxidant, protecting the cells and tissues from oxidative damage, or whether it actually stimulates oxidation and can cause problems.