title: Comparison of narrowband ultraviolet B exposure and oral vitamin D substitution on serum 25-hydroxyvitamin D concentration.
abstract: BACKGROUND
  A short course of narrowband ultraviolet B (NB-UVB) exposures increases the serum 25-hydroxyvitamin D [25(OH)D] concentration in patients with psoriasis and healthy subjects.
  
  
  OBJECTIVE
  To compare the effects of NB-UVB and oral vitamin D substitution in healthy subjects in winter.
  
  
  METHODS
  Healthy adult hospital employees and medical students were screened for serum 25(OH)D concentration. Those with 25(OH)D below 75 nmol L(-1) were randomly given either 12 NB-UVB exposures or 20 μg of oral cholecalciferol daily for 4 weeks. The NB-UVB exposures were given with a Waldmann UV 7001 cabin and the mean cumulative dose was 48·4 standard erythema doses. Serum 25(OH)D was measured before and after the treatments by radioimmunoassay.
  
  
  RESULTS
  The baseline serum 25(OH)D concentrations were 52·9 ± 10·4 (mean ± SD) in the 33 NB-UVB-treated and 53·5 ± 12·7 nmol L(-1) in the 30 oral cholecalciferol-treated subjects. The mean increase in serum 25(OH)D was 41·0 nmol L(-1) [95% confidence interval (CI) 34·8-47·2; P < 0·001] in the NB-UVB group and 20·2 nmol L(-1) (95% CI 14·6-26·0; P < 0·001) in the cholecalciferol group. The difference between the two treatments was significant at 2 weeks (P = 0·033) and at 4 weeks (P < 0·001). One month after the treatments the 25(OH)D concentrations had increased further.
  
  
  CONCLUSIONS
  The present study shows that 12 NB-UVB exposures given during 4 weeks increase serum 25(OH)D concentration significantly more than 20 μg of oral cholecalciferol daily. A short NB-UVB course is an effective way to improve vitamin D balance in winter and the response is still evident 2 months after the course.
authors.affiliation: Department of Dermatology, Tampere University Hospital, PO Box 2000, FIN-33521, Tampere, Finland. meri.ala-houhala@pshp.fi
authors.forename: M J
authors.initials: MJ
authors.lastname: Ala-Houhala
authors.forename: K
authors.initials: K
authors.lastname: Vähävihu
authors.forename: T
authors.initials: T
authors.lastname: Hasan
authors.forename: H
authors.initials: H
authors.lastname: Kautiainen
authors.forename: L
authors.initials: L
authors.lastname: Ylianttila
authors.forename: H T
authors.initials: HT
authors.lastname: Viljakainen
authors.forename: E
authors.initials: E
authors.lastname: Snellman
authors.forename: T
authors.initials: T
authors.lastname: Reunala
mesh_terms: D000284:Administration, Oral; D000293:Adolescent; D000328:Adult; D000368:Aged; D004032:Diet; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D014467:Ultraviolet Therapy / Q000379:methods*; D014807:Vitamin D / Q000008:administration & dosage* / Q000031:analogs & derivatives* / Q000378:metabolism; D014808:Vitamin D Deficiency / Q000097:blood / Q000532:radiotherapy; D014815:Vitamins / Q000008:administration & dosage*; D055815:Young Adult
chemical_list: D014815:Vitamins; D014807:Vitamin D; C104450:25-hydroxyvitamin D