In iron-deficiency anemia, the body does not have enough iron to form hemoglobin, which means there is not enough hemoglobin to carry oxygen to the whole body. The body gets its iron from food. The main foods that contain iron are meat and shellfish as well as iron-fortified foods (that is, foods that have iron added). A steady supply of iron is needed to form hemoglobin and healthy red blood cells.

A person can have low iron levels for three reasons:

Iron-deficiency anemia also can develop when the body needs higher levels of iron, such as during pregnancy.