Typically, vitamin D in vitamins promotes calcium absorption. Vitamin D in the body, in conjunction with thyroxine, can re-break down and synthesize the calcium in the bones, so that the calcium in the bone cells of the human body is better utilized, and promote the calcification of bone tissue. Vitamin D can act on the surface of intestinal cells and promote the synthesis of calcium-binding protein by epithelial cells in the intestines, thus promoting the absorption of calcium in the intestines. When the concentration of calcium in the body decreases, vitamin D can promote the reabsorption of calcium excreted in the urine by the kidneys, thus reducing calcium loss. It is important to note that the intake of vitamin D in the body should be ensured in a timely manner so as not to lead to a decrease in calcium absorption.