Vitamin D production depends on ultraviolet-B dose but not on dose rate: a randomized controlled trial

Exp Dermatol. 2011 Jan;20(1):14-8. doi: 10.1111/j.1600-0625.2010.01201.x.


Ultraviolet-B (UV-B) radiation increases serum vitamin D level expressed as 25-hydroxyvitamin D(3) (25(OH)D), but the dose-response relationship and the importance of dose rate is unclear. Of 172 fair-skinned persons screened for 25(OH)D, 55 with insufficient baseline 25(OH)D≤50 nm (mean 31.2 nm) were selected and randomized to one of 11 groups of five participants. Each group was exposed to one of four different UV-B doses: 0.375, 0.75, 1.5 or 3.0 standard erythema dose (SED) for 1, 5, 10 or 20 min. All participants had four UV-B sessions with 2- to 3-day interval with 24% of their skin exposed. Skin pigmentation and 25(OH)D were measured before and after the irradiations. The increase in 25(OH)D after UV-B exposure (adjusted for baseline 25(OH)D) was positively correlated with the UV-B dose (P=0.001; R(2) =0.176) but not to dose rate (1-20 min). 25(OH)D increased in response to four UV-B treatments of 3 SED with 24.8 nm on average and 14.2 nm after four UV-B treatments of just 0.375 SED. In conclusion, the increase in 25(OH)D after UV-B exposure depends on the dose but not on the dose rate (1-20 min). Further, a significant increase in 25(OH)D was achieved with a very low UV-B dose.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Dose-Response Relationship, Radiation
  • Female
  • Humans
  • Male
  • Middle Aged
  • Skin / metabolism*
  • Skin / radiation effects*
  • Skin Pigmentation
  • Sunlight
  • Ultraviolet Rays*
  • Vitamin D / analogs & derivatives
  • Vitamin D / biosynthesis*
  • Vitamin D / blood
  • Young Adult


  • Vitamin D
  • 25-hydroxyvitamin D