In general, vitamin D is found in animal source foods, particularly fish, meat, offal, egg and dairy.
Vitamin D is found in fungi and is produced by ultraviolet irradiation of ergosterol. The vitamin D content in mushrooms and Cladina arbuscula, a lichen, increases with exposure to ultraviolet light, and is stimulated by industrial ultraviolet lamps for fortification. The United States Department of Agriculture reports D and D content combined in one value.