What is Vitamin D?
Vitamin D is a hormone that can be made in the human body or consumed in food or supplements. Because the body can make its own vitamin D from sun exposure on the skin, it has been known as the “sunshine vitamin.” It is also commonly added to foods such as milk, baked goods, and cereals to help increase calcium absorption.
- Contrary to common belief, the skin itself does not make the vitamin D used in the body.
- Instead, sunshine triggers the skin to produce cholecalciferol, a substance that the liver converts to calcidiol.
- The kidneys then convert this to calcitriol, the active form of vitamin D.1