Vitamin D3 is involved in the regulation of calcium-phosphorus metabolism, enhances the absorption of calcium and phosphates in the intestine (by increasing the permeability of the cellular and mitochondrial membranes of the intestinal epithelium) and their reabsorption in the renal tubules of the kidneys; promotes bone mineralization, the formation of the bone skeleton and teeth in children, enhances the ossification process, is necessary for the normal functioning of the parathyroid glands.