Which form of vitamin D is most abundant in the body?

Which form of vitamin D is most abundant in the body?

• A. Vitamin D2
• B. Vitamin D3
• C. 25-hydroxy Vitamin D
• D. 1,25-dihydroxy Vitamin D

Answer: (B)

Vitamin D forms vary in how much of each is present in the body, and the form that serves as the main reservoir is the parent compound, D3. This cholecalciferol form is produced in the skin and comes from animal-based foods; it’s fat-soluble and tends to accumulate in body fat, supplying the largest overall pool of vitamin D. The liver then converts some D3 to 25-hydroxy vitamin D, which circulates in the blood and is used to assess vitamin D status, but this metabolite is derived from D3 and does not represent the largest store in the body. The active hormone form, 1,25-dihydroxy vitamin D, is present in much smaller amounts because its production is tightly regulated. So, the form most abundant in the body is vitamin D3.

Vitamin D forms vary in how much of each is present in the body, and the form that serves as the main reservoir is the parent compound, D3. This cholecalciferol form is produced in the skin and comes from animal-based foods; it’s fat-soluble and tends to accumulate in body fat, supplying the largest overall pool of vitamin D. The liver then converts some D3 to 25-hydroxy vitamin D, which circulates in the blood and is used to assess vitamin D status, but this metabolite is derived from D3 and does not represent the largest store in the body. The active hormone form, 1,25-dihydroxy vitamin D, is present in much smaller amounts because its production is tightly regulated. So, the form most abundant in the body is vitamin D3.