Vitamin D3 is the form of vitamin D the human body makes when sunlight strikes the skin. The body can’t manufacture vitamin D2. Vitamin D3 is found in animal sources of foods, like fatty fish and fish oil, liver, organ meats, and egg yolks.

Vitamin D3 is an essential vitamin that your skin produces in response to sunlight exposure. It can also be consumed through a variety of animal and plant-sourced foods.

Vitamin D is a general term that refers to both vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol). Vitamin D3 is produced naturally in the skin upon sun exposure and is available in animal foods, such as salmon and egg yolks. Vitamin D2 comes from mushrooms and fortified foods.

Vitamin D3, also called cholecalciferol, is what gives the “sunshine” vitamin its name. D3 is produced in our body from exposure to sunlight, Prest explains. Both vitamin D2 and vitamin D3 will help to increase vitamin D levels in the blood, says Pelitera.