Vitamin D3
Cholecalciferol
Fat-soluble vitamin essential for calcium absorption and bone health. FDA RDI for adults 4+ is 20 mcg (800 IU) per day.
FDA Reference Data
About Vitamin D3
Vitamin D3 (cholecalciferol) is the form of vitamin D synthesized by human skin upon UV exposure. It is one of four mandatory dietary ingredients on Supplement Facts labels per FDA 21 CFR 101.36(b)(2) (alongside calcium, iron, and potassium). Vitamin D3 is typically declared in micrograms (mcg) on FDA-compliant labels; the older IU unit is permitted as a secondary declaration. Labels must round vitamin D amounts per 21 CFR 101.36(b)(2)(iii) (mcg < 10 rounds to 0.1).
Common Supplement Forms
Note: When a salt form is used, the Supplement Facts panel must declare the elemental amount (e.g., “Magnesium 141 mg 34%”), not the salt weight. The salt name appears in the ingredient list below the panel. See %DV calculator for calculation details.
Frequently Asked Questions
What is the FDA RDI for Vitamin D3 on Supplement Facts labels?
The FDA Reference Daily Intake (RDI) for Vitamin D is 20 mcg (800 IU) per day for adults and children 4 years and older, established under 21 CFR 101.9(c)(8)(iv). This value applies to both D2 and D3 forms. Supplement Facts labels must declare vitamin D in mcg; IU may appear as a secondary declaration in parentheses.
How do I convert Vitamin D from IU to mcg for my Supplement Facts label?
1 mcg of vitamin D equals 40 IU. To convert IU to mcg, divide by 40. For example, 1000 IU of vitamin D3 = 25 mcg. FDA 21 CFR 101.36 requires the mcg unit on the label; the IU value may optionally appear in parentheses alongside the mcg value.
Is Vitamin D mandatory on Supplement Facts labels?
Yes. Vitamin D is one of four mandatory dietary ingredients per FDA 21 CFR 101.36(b)(2)(i), alongside calcium, iron, and potassium. If present in the product at any detectable level, it must be declared with its amount and %Daily Value. If absent, the label must still show "Vitamin D 0 mcg 0%" to maintain the mandatory line item.
What is the difference between D2 and D3 on a Supplement Facts label?
Both forms declare as "Vitamin D" on Supplement Facts labels (no D2/D3 distinction required by FDA). However, D3 (cholecalciferol, from lanolin) is more effective at raising and maintaining serum 25(OH)D levels. The source form may appear in the ingredient list (e.g., "Cholecalciferol") but the nutrient declaration uses the unified "Vitamin D" name.
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