Anemia is a condition when there are too few red blood cells in the body.
Iron deficiency anemia (IDA) is one type of anemia where there is not enough iron in the blood.
The main job of red blood cells is to carry oxygen from your lungs to all the organs and tissues in your body. A red blood cell is full of a protein, called hemoglobin, which carries the oxygen. Iron is an essential part of hemoglobin. Iron is needed to help make hemoglobin and to help carry oxygen.
When people lack a sufficient amount of iron, fewer red blood cells are made and each red cell has smaller amounts of hemoglobin. As a result, people who are iron deficient can become very anemic.