What kind of vitamin D is best?
However, a clinical study reported in 2008 suggested that vitamin D2 works as well as vitamin D3.
Many supplements contain vitamin D as vitamin D2 or calciferol. It's derived from irradiated fungus. Because this is not the form of vitamin D naturally made by your body, WebMD nutritionist Kathleen M. Zelman, MPH, RD, recommends using the D3 form for those taking vitamin D supplements.
Because of its potency, different forms of vitamin D are used in prescription medications. If you have a prescription for one of these medications, do not switch to another form of vitamin D without checking with your doctor.