Iron is a mineral that the body needs to produce red blood cells. When the body does not get enough iron, it cannot produce the number of normal red blood cells needed to keep you in good health. This condition is called iron deficiency (iron shortage) or iron deficiency anemia. Although many people in the U.S. get enough iron from their diet, some must take additional amounts to meet their needs. Your doctor can determine if you have an iron deficiency, what is causing the deficiency, and if an iron supplement is necessary.