Iron-deficiency anemia (or iron-deficiency anaemia) is a common type of anemia. It is caused by not having enough iron in food, not absorbing the iron in food, and/or losing iron because of bleeding.
Iron deficiency causes approximately half of all anemia cases worldwide, and affects women more often than men. This is partly because most women have periods (menstruate). There are probably more than one billion people who have anemia.