What is the difference between vitamins D2 and D3?

Vitamin D-3, also known as cholecalciferol, is the vitamin's natural form that the body derives from sunlight, according to WebMD. Vitamin D-2, or calciferol, comes from irradiated fungus and is not a natural product of the body.

A research study from 2008 indicated that the two forms of vitamin D work equally well for supplementation, notes WebMD. However, some nutritionists recommend using vitamin D-3 for supplementation because it is the form that the body makes. If a physician has recommended a particular form for supplementation, it is important to talk to the physician before changing types. The potency of the supplements means that switching may have negative health consequences.