What type of vitamin D supplement is best?

Two forms of vitamin D are used in supplements: vitamin D2 (“ergocalciferol,” or pre-vitamin D) and vitamin D3 (“cholecalciferol”). Vitamin D3 is chemically indistinguishable from the form of vitamin D produced in the body, and there’s evidence that it may be more effective than vitamin D2 at raising vitamin D levels in the blood. That’s why some scientists recommend looking for vitamin supplements that contain vitamin D3. Other scientists believe that vitamin D2 and vitamin D3 are similarly effective. Indeed, high dose vitamin D2 is available by prescription, and doctors regularly prescribe it to restore vitamin D levels in people who are deficient. As it turns out, the marketplace may answer the vitamin D question for you: More and more supplement makers offer vitamin D3 in their products.