Vitamin D is a steroid derivative that can effectively promote the absorption of calcium, and also has a certain influence on the hormones in the body, even on the normal functioning of the metabolic system and the health of the circulatory system, which are inextricably linked. Daily dietary therapy can be carried out, more vitamin D-rich food to supplement, such as fatty fish, including tuna and eel, especially red salmon rich in vitamin D, which is why vitamin D is usually produced together with fish oil. In the early stages of vitamin D deficiency, a daily diet can improve the deficiency, as well as the body’s ability to synthesize vitamin D by sunbathing, as ultraviolet light tends to make the skin susceptible to vitamin D. For infants and young children, vitamin D drops can be taken directly to improve the body’s stock of vitamin D. For children, vitamin D can be absorbed by eating foods that are easier to digest, such as beef liver and fish liver, and for adults, vitamin D can be produced through artificial ultraviolet light. Vitamin D deficiency puts a lot of pressure on calcium absorption and can be alleviated and improved if care is taken in the early stages of the disease, but in more severe cases, medication is needed.