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Types of Vitamin D3

Vitamin D comes in two distinct forms: D2 and D3. Vitamin D2 is derived from plants and according to a 2004 study published in the Journal of Clinical Endocrinology & Metabolism, it is not as potent and does not remain as active in the body for as long as vitamin D3. Vitamin D3 occurs naturally in the human body and can exist in three different forms, each with a distinct purpose.

  1. Cholecalciferol

    • Vitamin D3 occurs naturally in the form of cholecalciferol. The skin produces cholecalciferol when exposed to sunlight. According to a 2005 report in the Journal of Applied Nutrition, twenty minutes of sunlight absorption can produce 20,000 international units (IU) of cholecalciferol in the body. According to the Mayo Clinic, vitamin D3's primary function is to maintain normal levels of calcium and phosphorous in the blood. It also helps the body to absorb calcium to build strong bones.

    Calcidiol

    • Calcidiol is the vitamin D3 pre-hormone that is measured when doctors test your blood for vitamin D levels. It is naturally produced as the liver processes cholecalciferol. As a supplement it can be used as part of a treatment plan for rickets and osteomalacia. Calcidiol then moves to the kidneys where it is processed into the third form of vitamin D3.

    Calcitriol

    • When the kidneys process calcidiol, it becomes the third form of vitamin D3, calcitriol. Its natural function is to help the intestines absorb calcium into the blood stream. Calcitriol is often prescribed as a prescription medicine to help control calcium levels in the blood of patients whose kidneys are impaired.

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