Selenium is praised as the "fire of life" by medical and nutritional circles at home and abroad, and enjoys the reputation of "longevity element" and "king of cancer". The content of selenium in human body is one in ten million, but it determines the existence of life, and its great effect on human health is irreplaceable by other substances. Selenium supplement is selenium supplement. Selenium and vitamin E are both antioxidants, and they complement each other, which can prevent aging caused by oxidation, slow down its changes, activate the immune system and prevent cancer. 50 micrograms of selenium is an essential trace element for human body every day. Selenium can enhance human immune function, resist oxidation, delay aging, effectively inhibit tumor growth, and has a good auxiliary improvement effect on patients after surgery and radiotherapy and chemotherapy.