What is anemia?

Red blood cells use the protein hemoglobin to carry oxygen from the lungs to every tissue, so a shortage leaves people tired, pale and short of breath. The most common cause worldwide is iron deficiency, since iron is needed to make hemoglobin. Other causes include vitamin B12 or folate deficiency, blood loss and inherited conditions such as sickle cell disease. The World Health Organization estimates anemia affects around 40 percent of children under five and about 30 percent of women of reproductive age. Treatment depends on the cause and may involve iron supplements, dietary changes or treating underlying disease.