Vitamin-D or ‘sunshine mineral’ is synthesized by the Integumentary system of the human body.

To make Vitamin-D the skin contians a cholesterol pigment Provitamin D3, which when reacts with Ultraviolet in the sunrays forms Vitamin D3.

From there, the body takes over, first passing the vitamin D through the liver and then through the kidneys, converting it along the way into the form that the body needs.