There are many roles and effects of vitamin D3. First, vitamin D3 can promote the absorption of calcium and phosphorus in the human intestine, effectively saturate the human body with calcium and phosphorus, promote the balance of citric acid in human serum, and effectively reduce electrolyte disorders. Secondly, it promotes the calcification of human bones, effectively protects teeth and promotes the growth and development of human bones, which is beneficial to the height growth of teenagers. In addition, it prevents the loss of amino acids from the kidneys, improves immunity and resistance, and reduces the appearance of cancer in the human body. It also has a positive effect on the placenta of pregnant women and the growth and development of the fetus, effectively preventing miscarriage, premature birth and slow fetal development. There are many roles and effects of vitamin D3, and moderate supplementation of vitamin D3 has a positive effect on the quality of human health.