What type of vitamin D do you use?

We use a natural vitamin D3 (cholecalciferol) made from lanolin.
Lanolin is a fat that naturally occurs in sheepʼs wool.
Vitamin D is made by dissolving a precursor to vitamin D in lanolin.
It is then chemically altered and activated by exposure to ultraviolet (UV) light.
This chemical process is comparable to the process occurring in human skin when it produces vitamin D.