D3 is commonly known 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 radiation can form vitamin D3, vitamin D3 and sunlight is closely related, so it is also known as the sunshine vitamin. Vitamin D3 has very important roles, such as participating in the body’s immunity, reducing the incidence of certain cancers, regulating calcium and phosphorus metabolism, lowering blood sugar, for example, can reduce the prevalence of type 1 diabetes. Vitamin D3 can be ingested in daily life through the intake of fish, fish eggs, animal liver, egg yolk, cream, etc. If these foods are not enough intake can also be supplemented by fortified foods, foods fortified with vitamin D3 or through the use of cod liver oil.