Utah Master Esthetician Practice Exam

Which vitamin is synthesized in the skin upon exposure to sunlight?

1. Vitamin A

2. Vitamin C

3. Vitamin D

4. Vitamin E

The correct answer is: Vitamin D

The synthesis of vitamin D in the skin occurs when it is exposed to ultraviolet (UV) radiation from sunlight. Specifically, UVB rays facilitate the conversion of 7-dehydrocholesterol, a substance found in the skin, into previtamin D3. This then undergoes further transformations in the body to become active vitamin D, which plays a vital role in calcium absorption, bone health, and immune function. The other vitamins listed do not undergo a synthesis process in the skin upon sunlight exposure. Vitamin A is primarily obtained through dietary sources and is not synthesized from sunlight; rather, it can be converted from carotenoids found in plant sources after ingestion. Vitamin C is also not synthesized in the skin; it must be obtained from dietary intake, particularly from fruits and vegetables. Vitamin E, while important for skin health, is likewise absorbed through diet and not synthesized in response to sunlight. Thus, vitamin D is unique among these options for its ability to be produced in the skin when exposed to sunlight, making it the correct answer.