The vitamin that promotes calcium absorption is vitamin D. There are many calcium supplements on the market that contain calcium and vitamin D. The main role of vitamin D in the body is to promote intestinal absorption of calcium and phosphorus, and fish oil, egg yolk and liver are relatively rich in vitamin D. The human skin also stores the precursor material for vitamin D. When exposed to ultraviolet light from the sun, this precursor material can be converted into vitamin D. Children with insufficient vitamin D will get rickets; adults with insufficient vitamin D will get chondromalacia, so vitamin D is also called anti-rickets vitamin. Proper outdoor activities and sun exposure are especially important for growing children. Of course, it is not possible to oversupply vitamin D for a long time, too much vitamin D in the body will vitamin D poisoning and also problems, more sunshine will not cause vitamin D poisoning.