Vitamin D3 does not belong to calcium, the two are two different components, vitamin D3 is a kind of vitamin, calcium belongs to the trace elements of 1 kind. The reason for this statement is that children are prone to vitamin D deficiency rickets, commonly known as calcium deficiency in children, but the underlying cause of calcium deficiency is caused by vitamin D deficiency, so doctors will prescribe vitamin D3 to children, which can play a significant calcium supplementation effect, parents will have such questions. Since after vitamin D deficiency, calcium absorption in the intestine of children will be affected. It will cause hypocalcemia, which will cause vitamin D deficiency rickets, and children will have symptoms such as occipital baldness, chicken chest, X-leg and O-leg, so vitamin D3 is not calcium.