title: Vitamin D production depends on ultraviolet-B dose but not on dose rate: a randomized controlled trial.
abstract: 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.
authors.affiliation: Department of Dermatology, Copenhagen University Hospital, Bispebjerg, Denmark. bogh@dadlnet.dk
authors.forename: Morten K B
authors.initials: MK
authors.lastname: Bogh
authors.forename: Anne V
authors.initials: AV
authors.lastname: Schmedes
authors.forename: Peter A
authors.initials: PA
authors.lastname: Philipsen
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Thieden
authors.forename: Hans Christian
authors.initials: HC
authors.lastname: Wulf
mesh_terms: D000293:Adolescent; D000328:Adult; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012867:Skin / Q000378:metabolism* / Q000528:radiation effects*; D012880:Skin Pigmentation; D013472:Sunlight; D014466:Ultraviolet Rays; D014807:Vitamin D / Q000031:analogs & derivatives / Q000096:biosynthesis* / Q000097:blood; D055815:Young Adult
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D