What is used by the body to synthesize Vitamin D?

The body synthesizes vitamin D primarily through exposure to ultraviolet B (UVB) rays from sunlight. When the skin is exposed to UVB radiation, it converts 7-dehydrocholesterol, a compound present in the skin, into previtamin D3, which is then transformed into active vitamin D (calcitriol) through further processes in the liver and kidneys. Additionally, vitamin D can be obtained from dietary sources and supplements.