What is the difference between Vitamin D2 and D3?

Dariush Mozaffarian, MD
Internal Medicine
Vitamin D comes in two forms: D3 (cholecalciferol) and D2 (ergocalciferol). D3, the form made by the body, is also the form most often used to fortify milk and other foods, such as breakfast cereals. Vitamin supplements contain either D3 or D2, which is made from plant material. If you take supplements, some experts recommend choosing one that contains D3. However, an Institute of Medicine (IOM) report concludes that D2 is just as effective as D3 at the recommended dosage levels.
Both vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol) are found in supplements and in food. Vitamin D3 is also manufactured in your skin when you are in the sun. For years, scientists thought that supplements of vitamin D2 and vitamin D3 were equal in terms of their benefits. However recent studies have found that vitamin D2 is less stable and less effective than vitamin D3 at raising blood levels of vitamin D. For these reasons, some experts recommend using only vitamin D3 in supplements. Talk to your own doctor about whether you need to take vitamin D supplements and what is best for you.
Vitamin D is a group of fat-soluble vitamins. There are 2 major forms of Vitamin D which are vitamin D2 also known as ergocalciferol and vitamin D3 which is also known as cholecalciferol. Both D2 and D3 are in the same structural class and are very similar compounds. Vitamin D3 is produced in your skin naturally when it is exposed to sunlight. Vitamin D2 is made by some plants and fungus in response to ultraviolet light. In humans, D3 is as effective as D2 in vitamin D related hormone activity in the body. However, there have been some recent arguments that D3 is more effective than D2. Both vitamin D2 and D3 are used for human nutritional supplementation, are available commercially and are indicated for a variety of conditions under the direction of a doctor.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.