Medically reviewed by Ashley Baumohl, RD Vitamin D (calciferol) is a fat-soluble vitamin that helps support strong bones, ...

The two main forms of vitamin D are vitamin D2 and vitamin D3. Vitamin D2 comes from plants and fortified foods, while vitamin D3 comes from sunlight when it touches the skin and animal products.

Vitamin D supplements are popular for bone health and immunity. When is the best time to take vitamin D? Here's how to take it properly, according to experts.

Another fatty fish that is an excellent source of vitamin D is the swordfish. The USDA lists a 100-gram serving as containing 666 IU of vitamin D. That's over the 600 IU daily recommendation for ...

There are two types of vitamin D supplements available for over-the-counter purchase (vitamin D2 and vitamin D3). Vitamin D3 is the type that most experts believe should be utilized in clinical ...

There are two primary forms of vitamin D—D2 (ergocalciferol) and D3 (cholecalciferol). A vitamin D test, specifically the 25-hydroxyvitamin D blood test, is used to diagnose deficiency.