What vitamin does the sun provide?

Sunlight is the key to vitamin D. The ultraviolet B energy, also referred to as UVB, from the sun is the catalyst for turning the body's natural 7-dehydrocholesterol chemical into vitamin D3, explains Sukhsatej Batra for SFGate.

The production of ultraviolet rays is the first step in the sun's process to produce vitamin D. Once the rays are absorbed by human skin exposed to direct sunlight, a chemical reaction occurs resulting in the production of vitamin D3. According to Harvard Medical School, a lack of direct sunlight, skin pigmentation, sunscreen, medical issues and advanced age affect absorption of ultraviolet rays resulting in the body's inability to process the natural chemical reaction.