Oxygen is distributed throughout the body by red blood cells, which contain an oxygen-carrying molecule called hemoglobin. Hemoglobin's ability to carry oxygen depends on iron. Red blood cells live for about 120 days. When they die, their iron is re-used to create new red blood cells. Anemia develops when heavy bleeding causes significant iron loss, if red blood cell production slows down, or if red blood cells are destroyed more rapidly than normal.

Poor diet can contribute to vitamin and iron deficiency anemias in which fewer red blood cells are produced. Hereditary disorders and certain diseases can cause increased blood cell destruction. However, excessive bleeding is the most common cause of anemia. Anemia can be mild, moderate, or severe enough to lead to life-threatening complications. More than 400 different types exist.

Iron deficiency anemia is the most common form of anemia. The deficiency occurs when the body loses more iron...