The main vitamin that promotes calcium absorption is vitamin D. Vitamin D is a fat-soluble vitamin that is deficient in naturally occurring foods and is found mainly in the liver of fish and lanolin. The main role of vitamin D is to promote calcium and phosphorus absorption in the intestine, thus allowing calcium and phosphorus from food in the intestine to enter the bloodstream. Vitamin D is commonly used clinically to prevent and treat rickets, among other things. Vitamin D plays a very important role in the absorption of calcium, there is evidence that if no vitamin D is added, the absorption rate of calcium is very low, about 20%-30%, but if the right amount of vitamin D is added, the absorption rate of calcium can be increased to 80%. Vitamin D belongs to fat-soluble vitamins, overuse is prone to toxic symptoms, such as nausea, vomiting, etc.; Hypercalcemia, hypervitaminosis D, hyperphosphatemia with renal rickets is prohibited. It is recommended to use under the guidance of a doctor.