Vitamin D supplements are available in two forms: D2, known as ergocalciferol, and D3, known as cholecalciferol. Vitamin D3 is found largely in animal-based foods, such as oily fish, eggs and butter. The only plant that contains this form is lichen, an algae-fungal hybrid microorganism that grows on trees and stones. Vitamin D2, on the other hand, comes mostly from dietary supplements, fortified foods, and mushrooms grown in UV light. Both of these chemical compounds contribute to your daily vitamin D requirements, but they may have a slightly different effect on our bodies.
According to the researchers from The American Journal of Clinical Nutrition, vitamin D3 supplements are generally better than the ones with vitamin D2 at raising the blood serum vitamin D levels. As such, products containing cholecalciferol may be more cost-effective.