Vitamin D is a very important element, the main role of vitamin D in the body is to promote the absorption of calcium from the gastrointestinal tract. The role of vitamin D is to promote the absorption of calcium from the gastrointestinal tract after eating food or taking calcium supplements, and vitamin D has the role of promoting the absorption of calcium. Other aspects of the role is not too strong, vitamin D on the bones also have some effect, can let the blood in the middle of the calcium into the bones, but the most important is to help absorb calcium from the gastrointestinal tract.