Selenium in the human body is a very small amount of trace elements, but also essential trace elements. The main roles are as follows: 1, enhance immunity, selenium has the role of scavenging oxygen free radicals, discharging toxins from the body, antioxidant, can effectively inhibit the production of lipid peroxide, prevent blood clots, remove cholesterol, enhance the role of human resistance. 2, prevent diabetes, selenium is the active component of the composition of glutathione peroxidase, can prevent the oxidative destruction of insulin beta cells, so that its function is normal, promote 3, to prevent cataracts, the retina due to more exposure to ionizing radiation, easy to injury, selenium can protect the retina, enhance the vitreous polish, improve vision. 4, to prevent cardiovascular disease, selenium is an important element to maintain the normal function of the heart, for the heart myocardial cells with the role of protection and repair, the human blood selenium level is reduced, will lead to the body to remove free radicals The decrease in human blood selenium levels will lead to the body to remove free radicals, resulting in the deposition of harmful substances. Therefore, selenium has the above-mentioned roles, as far as possible to prevent electrolyte deficiency, including trace elements.