Iron deficiency anemia is caused by iron deficiency, as well as deficiency of folic acid, vitamin B12, vitamin B6, and other trace elements and proteins can cause anemia. There are many causes of anemia, which can be caused by insufficient intake, excessive loss, especially due to heavy menstruation in women, and digestive system diseases. All of these can cause reduced intake and high loss and cause anemia, which needs to be treated actively. If the anemia is caused by deficiency of folic acid and vitamin B12, it is macrocytic anemia and it also has some causes, such as partial diet and nutritional imbalance. Folic acid and vitamin B12 are often taken in green foods, meat and eggs, and long-term deficiency can cause megaloblastic anemia. Chronic malnutrition can cause microcytic anemia, such as chronic diseases.