Question

What is the role of skin in the synthesis of vitamin D?

Answer 1

Vitamin D:

1. Vitamin D₂ (ergocalciferol) is largely human-made and added to foods.
2. Vitamin D₃ (cholecalciferol) is synthesized in the skin of humans from 7-dehydrocholesterol and is also consumed in the diet via the intake of animal-based foods.
3. Vitamin D is a closely related compound. The synthesis of this vitamin starts when the precursor molecules are activated in the skin by the UV (ultraviolet) rays in the sunlight.
4. In the kidneys and the liver, the enzymes then modify the molecule ultimately yielding calcitriol, which is the most active form of vitamin D.
5. This calcitriol supplies the homeostasis of body fluids by assisting the process of absorption of calcium in the food.
6. As per the synthesis sequence explained, vitamin D is deemed to be a hormone as it is yielded in the body in one location and transported by the blood, and shows effect in the other location. Hence, skin is deemed to be an endocrine organ.