Low hemoglobin can be seen in physiological reduction, which can be improved by eating iron-rich foods to increase the Hb level. Pathological hemoglobin reduction is usually seen in various kinds of anemia, mild and moderate iron deficiency anemia, megaloblastic anemia, which can be improved by eating foods and preparations rich in iron and vitamin B12, etc. However, in severe patients, dietary therapy cannot achieve therapeutic effect, and iron supplements or blood transfusion therapy is usually required. Hemoglobin concentration of 30-59g/L is mild anemia, and 60-90g/L is moderate anemia, among which iron deficiency anemia and megaloblastic anemia are common. At this time, iron-rich foods can be added to the daily diet, including eggs, animal liver, vegetables and fruits, etc. Among the vegetables and fruits with more iron include celery, tomatoes, peaches, cherries, etc. The human body has a high absorption rate of iron from animal foods and a relatively low absorption rate of iron from plant foods. Patients with megaloblastic anemia can eat foods rich in vitamin B, vitamin B12, folic acid and other elements, such as avocado, spinach, green bamboo shoots, etc. Patients with moderate anemia also have to take oral iron, folic acid or vitamin B. The dietary supplement method can only be used as an auxiliary method. For patients with severe anemia, dietary supplementation methods are usually less effective and require active medical consultation to clarify the specific type of anemia. In case of severe iron deficiency anemia, iron supplements should be taken regularly and quantitatively, and the hemoglobin concentration should be reviewed. In severe megaloblastic anemia, patients also need to take oral folic acid and vitamin B12 preparations regularly and quantitatively, and review them regularly. Other types of anemia, such as hemolytic anemia, blood loss anemia, and aplastic anemia, have no role for dietary supplements, regardless of the severity of the disease. Patients need to be treated for the cause and may also need to be relieved by blood transfusion.