Cholecalciferol, also known as vitamin D3, is a type of vitamin D that is naturally produced in the skin when it is exposed to sunlight. It can also be obtained from dietary sources such as fatty fish, egg yolks, and fortified foods.

Cholecalciferol is important for bone health as it helps the body absorb calcium and phosphorus from food. It also plays a role in immune function and has been linked to a reduced risk of certain types of cancer, cardiovascular disease, and autoimmune disorders. In some cases, cholecalciferol supplements may be prescribed by healthcare professionals to treat vitamin D deficiency or certain medical conditions.