Fat-soluble vitamins
Vitamin D
Bone · immune
Calcium absorption, bone mineralization, immune modulation.
Upper-limit caution
The Tolerable Upper Intake Level for Vitamin D is 100 mcg per day. Routine intakes above this level — counting food + supplements — raise the risk of adverse effects. Multivitamins, fortified foods, and standalone supplements stack faster than people expect.
Forms to avoid
Not all Vitamin D forms absorb equally well. The following forms are commonly used because they're cheap, but their bioavailability is materially lower than alternatives — watch for them on supplement labels:
- d2
- ergocalciferol
Formulate's product scoring penalizes these forms when they appear as the primary Vitamin D source — see the methodology page for the rubric.
How Vitamin D appears on labels
Supplement labels list Vitamin D under several names depending on the chemical form used. Any of these on an ingredients panel counts toward your Vitamin D intake:
- vitamin d
- vitamin d3
- vitamin d2
- cholecalciferol
- ergocalciferol
Deep dive
For mechanism of action, dosing protocols, evidence grade, and interaction warnings on Vitamin D, see the full encyclopedia entry:
Vitamin D encyclopedia entry →Related fat-soluble vitamins
Track your full intake
Formulate's free desktop app aggregates Vitamin D (and ~40 other nutrients) across every supplement in your stack — flagging underdoses, overlaps, and upper-limit overshoots in one view.
Get the appMedical disclaimer. This page is educational and does not replace advice from a qualified healthcare provider. Targets and upper limits are general adult reference values; individual needs vary by age, sex, pregnancy status, and clinical context.