Essential D3 1000 IU 60 Capsules Is Dietary Supplement Capsules That Contain Vitamin D3. Vitamin D and its other forms are extremely important for our bones, teeth, and Immunity as the Vitamin is responsible for regulating the metabolism of calcium in our bodies. Cholecalciferol is vitamin D3. Vitamin D helps your body absorb calcium. Cholecalciferol is used as a dietary supplement in people who do not get enough vitamin D in their diets to maintain adequate health. Cholecalciferol may also be used for many purposes in terms of medication.