Iron is an important component of hemoglobin in red blood cells, and the function of red blood cells carrying oxygen and carbon dioxide depends on iron. Therefore, long-term iron deficiency in food can cause anemia. There are many sources of iron, such as lean meat, egg yolk, fish and breast milk. Among plant foods, jujube, hard fruit, hawthorn, walnut and strawberry contain more iron. Copper is an essential trace element for human body, which mainly participates in the biochemical process of human body in the form of cuprase. It binds to copper protein in blood cells and depends on iron. It is a catalyst for the absorption, utilization and operation of iron. Even if there is enough iron in the body, the lack of copper can lead to anemia. Therefore, eat more foods containing copper, such as fish, egg yolk, beans, walnuts, peanuts, mushrooms, spinach, almonds, eggplant, wheat, milk and so on. Folic acid, vitamin B 12 and vitamin C are not components of blood cells, but the lack of these vitamins will also affect hematopoiesis and even cause anemia. Fresh vegetables are rich in folic acid and vitamin C, especially green leafy vegetables and fruits. Vitamin B 12 is rich in meat, fish, brown rice and other foods.