Vitamin D3 can promote the absorption of calcium and phosphorus in the body, thus playing a role in the prevention and treatment of rickets, as well as stimulating the deposition of osteoblasts and bone salts, making bones stronger. Therefore, for infants and adolescents, vitamin D3 supplementation is routinely given. it also has an important role in the immune system, preventing infections and having an impact on autoimmune diseases, etc. It can act on the glomerulus and promote calcium reabsorption, while it can inhibit phosphorus reabsorption by the renal tubules, causing an increase in urinary phosphorus.