Which vitamin does the skin produce when exposed to sunlight?

The skin produces vitamin D when exposed to sunlight, specifically when ultraviolet B (UVB) rays interact with a cholesterol compound in the skin. This process begins when the skin absorbs UVB rays, which convert the compound to previtamin D3. This then undergoes further transformation in the body to become active vitamin D. Vitamin D plays a crucial role in numerous bodily functions, including calcium absorption and bone health. Additionally, it helps modulate immune system function and has been linked to skin health, influencing the skin barrier and reducing inflammation.

The other vitamins listed do not follow the same synthesis process in the skin. For example, vitamin A is primarily derived from dietary sources and is important for skin health but does not get produced from sunlight exposure. Vitamins B12 and C are also obtained from food sources and have distinct roles in the body but are not synthesized in the skin through sunlight exposure. Thus, vitamin D is the only vitamin in this context that is directly produced in the skin as a result of sunlight exposure.