Which vitamin is synthesized in the skin through sunlight exposure?

• A. Vitamin A
• B. Vitamin C
• C. Vitamin D
• D. Vitamin E

Answer: (C)

Vitamin D is synthesized in the skin when exposed to sunlight, specifically ultraviolet B (UVB) rays. The process begins when UVB rays convert 7-dehydrocholesterol, a compound found in the skin, into previtamin D3. This compound is then transformed into vitamin D3 (cholecalciferol), which eventually gets converted into its active form, calcitriol, in the liver and kidneys.

Vitamin D plays a crucial role in maintaining healthy bones by regulating calcium and phosphorus levels in the body. It is also important for immune function and has been linked to various other biological processes. The synthesis of vitamin D through sunlight exposure highlights the significance of sunlight in human health; however, it is also important to balance sun exposure to prevent skin damage and reduce the risk of skin cancer.