What is Vitamin D3?

Vitamin D3 is one of the two most common forms of vitamin D. (Vitamin D2 being the other.) Vitamin D2 is ergocalciferol and vitamin D3 is cholecalciferol. Vitamin D2 is mostly found in plant-based sources and fortified foods like cereals, dairy and plant “milks,” while vitamin D3 usually comes from animal-based foods.

D3 is the form of vitamin D your skin makes when exposed to sunlight, but four in 10 people worldwide are believed to fall short on their vitamin D intake. This happens for many reasons, but it can be due to location (getting adequate vitamin D from sun exposure is harder the farther you are from the Equator) and simply not spending time outdoors.

Vitamins D2 and D3 do not work the same way when it comes to increasing the amount of this fat-soluble vitamin that is found in your body. Both forms can be absorbed into the bloodstream, but the liver more effectively metabolizes D3. (This process is essential for creating the main form of vitamin D that circulates in your body, calcifediol.)

For this reason, many people choose vitamin D3 supplements over D2 versions.