Vitamin D2 is always vegan, but vitamin D3-or cholecalciferol-usually isn't vegan unless stated otherwise. Most commercially available D3 is made using lanolin washed from sheep's wool, but in recent years, vegan versions of vitamin D3 have become easier to find. These vegan versions of D3 are made either using algae or lichen-a composite organism that comes from a symbiotic partnership between fungi and algae or cyanobacteria.