process
Sunlight
UVB exposure can trigger vitamin D synthesis in uncovered skin.
Educational draft · Human scientific and editorial review pending. About review status
About Sunlight
Season, time of day, cloud cover, skin pigmentation, age, and other factors change UVB exposure and synthesis. Those variables make a single safe exposure target unreliable.
Where does vitamin D come from—and where does it go?Related topics
Sunlight helps skin make vitamin D.
UVB radiation can convert a compound in uncovered skin into previtamin D3, which then becomes vitamin D3.
Evidence: Established · Source checked 2026-09-04 · Sources: NIH Office of Dietary Supplements: Vitamin D: Fact Sheet for Health Professionals
References
Source-checked local draft.
Human editorial review pending.