The Rest of the Departments Practice Test

Sunlight enables the skin to produce vitamin D. Ultraviolet B radiation converts a cholesterol compound in the skin (7-dehydrocholesterol) into previtamin D3, which then becomes vitamin D3 (cholecalciferol). This vitamin travels to the liver and kidneys to be activated, where it plays a crucial role in calcium and phosphate balance for bone health. The other vitamins mentioned are not produced by sun exposure in the skin; they come from diet (or other sources) and serve different roles. So, the vitamin synthesized in the skin with sun exposure is vitamin D.