title: Efficacy of a dose range of simulated sunlight exposures in raising vitamin D status in South Asian adults: implications for targeted guidance on sun exposure.
abstract: BACKGROUND
  Vitamin D is essential for bone health, and cutaneous synthesis is an important source. South Asians cannot attain adequate amounts of vitamin D by following general recommendations on summer sunlight exposure at northerly latitudes, and increased exposure may be appropriate for improving their vitamin D status.
  
  
  OBJECTIVE
  We examined the efficacy of a dose range of simulated summer sunlight exposures in raising vitamin D status in UK adults of South Asian ethnicity.
  
  
  METHODS
  In a dose-response study, healthy adults of South Asian ethnicity (n = 60; 20-60 y old) received 1 of 6 ultraviolet exposures ranging from 0.65 to 3.9 standard erythema doses (SEDs), which were equivalent to 15-90 min unshaded noontime summer sunlight at 53.5°N (Manchester, United Kingdom), 3 times/wk for 6 wk, while wearing casual clothes that revealed a 35% skin area. Serum 25-hydroxyvitamin D [25(OH)D] was measured weekly, and dietary vitamin D was estimated.
  
  
  RESULTS
  At baseline, all completing participants (n = 51) were vitamin D insufficient [25(OH)D concentrations <20 ng/mL], and a high proportion of participants were deficient [35% of subjects had 25(OH)D concentrations <5 ng/mL, and 90% of subjects had 25(OH)D concentrations <10 ng/mL, which are concentrations at which osteomalacia and rickets occur). The 25(OH)D concentration rose significantly in all dose groups. Postcourse, all participants achieved 25(OH)D concentrations ≥5 ng/mL, whereas only 6 subjects attained 25(OH)D concentrations ≥20 ng/mL. Participants who received exposures ≥1.95 SEDs (equivalent to 45 min unshaded sunlight; n = 33) attained a mean (±SD) 25(OH)D concentration of 15.7 ± 5 ng/mL (mean rise: 8.7 ± 5.7 ng/mL; 95% CI: 6.8, 10.6 ng/mL; P < 0.001), and 94% of subjects achieved concentrations >10 ng/mL.
  
  
  CONCLUSIONS
  Targeted guidance on sunlight exposure could usefully enhance vitamin D status to avoid deficiency [25(OH)D concentration >10 ng/mL] in South Asians living at latitudes distant from the equator. This trial was registered at the ISRCTN Register (www.isrctn.org) as 07565297.
authors.affiliation: Dermatology Centre, Institute of Inflammation and Repair, University of Manchester, Manchester Academic Health Science Centre, Salford Royal National Health Service Foundation Trust, Manchester, United Kingdom.
authors.forename: Mark D
authors.initials: MD
authors.lastname: Farrar
authors.forename: Ann R
authors.initials: AR
authors.lastname: Webb
authors.forename: Richard
authors.initials: R
authors.lastname: Kift
authors.forename: Marie T
authors.initials: MT
authors.lastname: Durkin
authors.forename: Donald
authors.initials: D
authors.lastname: Allan
authors.forename: Annie
authors.initials: A
authors.lastname: Herbert
authors.forename: Jacqueline L
authors.initials: JL
authors.lastname: Berry
authors.forename: Lesley E
authors.initials: LE
authors.lastname: Rhodes
mesh_terms: D000328:Adult; D044466:Asian People / Q000208:ethnology*; D004032:Diet; D004307:Dose-Response Relationship, Radiation; D004890:Erythema / Q000503:physiopathology; D005260:Female; D017408:Guidelines as Topic; D006801:Humans; D008297:Male; D008875:Middle Aged; D009752:Nutritional Status; D010281:Parathyroid Hormone / Q000097:blood; D012279:Rickets / Q000097:blood / Q000209:etiology; D012621:Seasons; D012867:Skin / Q000378:metabolism* / Q000528:radiation effects; D013472:Sunlight; D016896:Treatment Outcome; D014466:Ultraviolet Rays; D006113:United Kingdom / Q000453:epidemiology; D014807:Vitamin D / Q000008:administration & dosage* / Q000097:blood*; D014808:Vitamin D Deficiency / Q000097:blood / Q000150:complications / Q000208:ethnology*; D055815:Young Adult
chemical_list: D010281:Parathyroid Hormone; D014807:Vitamin D