itamin D comes in 2 forms: vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol). Vitamin D2, found in plants, is the product of ultraviolet B (UVB) (290 to 315 mm) irradiation of ergosterol, and can be consumed as a supplement or in fortified foods (1). Vitamin D3, a product of UVB irradiation of 7-dehydrocholesterol, is synthesized in the human epidermis or consumed in the form of oily fish, fortified foods, or a supplement. Excessive sunlight exposure cannot cause vitamin D toxicity because UVB converts excess vitamin D3 to biologically inert isomers (1); however, excessive oral vitamin D intake can cause toxicity at very high doses (6).