D3 is usually referred to as vitamin D3, vitamin D3 is a fat-soluble vitamin, is the real active form of vitamin D in the body, mainly vitamin D3 in the body after cholesterol dehydrogenation to generate 7-dehydrocholesterol, and then by ultraviolet irradiation can be formed by vitamin D3, vitamin D3 is closely related to sunlight, so it is also known as the sunshine vitamin. Vitamin D3 has a very important role, such as participating in the body’s immune system, reduce the incidence of certain cancers, regulate calcium and phosphorus metabolism, reduce blood glucose, such as reducing the prevalence of type 1 diabetes. Vitamin D3 can be consumed in daily life through the intake of fish, fish eggs, animal liver, egg yolks, cream, etc. If the intake of these foods is insufficient, it can also be supplemented by fortified foods, foods fortified with vitamin D3 or through the use of cod liver oil.