Depending on age and region and comorbid diseases, each individual has a different degree of selenium deficiency, and the selenium supplementation program needs to be individualized. Generally, selenium supplementation for about 2 months will have obvious effects. Selenium can enhance the body’s immune function, antioxidant, delay aging, and can effectively inhibit tumor growth, and has a good auxiliary improvement effect on patients after surgery and radiotherapy treatment. Selenium supplementation can eat more organic selenium foods, such as fish, shrimp, seaweed, animal liver, garlic, asparagus, carrots, etc. Eat more fruits and vegetables rich in vitamin A, vitamin C, vitamin E and other foods to promote the absorption of selenium. If the desired effect is not achieved, it can also be supplemented by taking oral selenium-containing oral solution by mouth. Although selenium supplementation is necessary, but can not be blindly supplemented, excessive intake of selenium can lead to poisoning, hair loss, hair and nails break easily, intestinal disorder, rough skin, irritability and neurological dysfunction.