title: Comparing the effects of sun exposure and vitamin D supplementation on vitamin D insufficiency, and immune and cardio-metabolic function: the Sun Exposure and Vitamin D Supplementation (SEDS) Study.
abstract: BACKGROUND
  Adults living in the sunny Australian climate are at high risk of skin cancer, but vitamin D deficiency (defined here as a serum 25-hydroxyvitamin D (25(OH)D) concentration of less than 50 nmol/L) is also common. Vitamin D deficiency may be a risk factor for a range of diseases. However, the optimal strategies to achieve and maintain vitamin D adequacy (sun exposure, vitamin D supplementation or both), and whether sun exposure itself has benefits over and above initiating synthesis of vitamin D, remain unclear. The Sun Exposure and Vitamin D Supplementation (SEDS) Study aims to compare the effectiveness of sun exposure and vitamin D supplementation for the management of vitamin D insufficiency, and to test whether these management strategies differentially affect markers of immune and cardio-metabolic function.
  
  
  METHODS
  The SEDS Study is a multi-centre, randomised controlled trial of two different daily doses of vitamin D supplementation, and placebo, in conjunction with guidance on two different patterns of sun exposure. Participants recruited from across Australia are aged 18-64 years and have a recent vitamin D test result showing a serum 25(OH)D level of 40-60 nmol/L.
  
  
  CONCLUSIONS
  This paper discusses the rationale behind the study design, and considers the challenges but necessity of data collection within a non-institutionalised adult population, in order to address the study aims. We also discuss the challenges of participant recruitment and retention, ongoing engagement of referring medical practitioners and address issues of compliance and participant retention.
  
  
  BACKGROUND
  Australia New Zealand Clinical Trials Registry: ACTRN12613000290796 Registered 14 March 2013.
authors.affiliation: National Centre for Epidemiology and Population Health, The Australian National University, Canberra, Australian Capital Territory, 2600, Australia. mica.hartley@anu.edu.au.
authors.forename: Mica
authors.initials: M
authors.lastname: Hartley
authors.affiliation: National Centre for Epidemiology and Population Health, The Australian National University, Canberra, Australian Capital Territory, 2600, Australia. sam.hoare@dhhs.tas.gov.au.|Department of Health and Human Services, Hobart, Tasmania, Australia. sam.hoare@dhhs.tas.gov.au.
authors.forename: Samuel
authors.initials: S
authors.lastname: Hoare
authors.affiliation: University of Canberra, Canberra, Australian Capital Territory, Australia. Fiona.Lithander@canberra.edu.au.
authors.forename: Fiona E
authors.initials: FE
authors.lastname: Lithander
authors.affiliation: QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia. Rachel.Neale@qimrberghofer.edu.au.
authors.forename: Rachel E
authors.initials: RE
authors.lastname: Neale
authors.affiliation: Telethon Kids Institute, The University of Western Australia, Perth, Western Australia, Australia. prue.hart@telethonkids.org.au.
authors.forename: Prue H
authors.initials: PH
authors.lastname: Hart
authors.affiliation: Telethon Kids Institute, The University of Western Australia, Perth, Western Australia, Australia. shelley.gorman@telethonkids.org.au.
authors.forename: Shelley
authors.initials: S
authors.lastname: Gorman
authors.affiliation: Australian Radiation Protection and Nuclear Safety Agency, Melbourne, Victoria, Australia. peter.gies@arpansa.gov.au.
authors.forename: Peter
authors.initials: P
authors.lastname: Gies
authors.affiliation: Curtin University, Perth, Western Australia, Australia. jill.sherriff@curtin.edu.au.
authors.forename: Jill
authors.initials: J
authors.lastname: Sherriff
authors.affiliation: The Canberra Hospital, Canberra, Australian Capital Territory, Australia. Ashwin.Swaminathan@act.gov.au.
authors.forename: Ashwin
authors.initials: A
authors.lastname: Swaminathan
authors.affiliation: School of Medicine and Pharmacology, Royal Perth Hospital Unit, University of Western Australia, Perth, Western Australia, Australia. lawrie.beilin@uwa.edu.au.
authors.forename: Lawrence J
authors.initials: LJ
authors.lastname: Beilin
authors.affiliation: School of Medicine and Pharmacology, Royal Perth Hospital Unit, University of Western Australia, Perth, Western Australia, Australia. trevor.mori@uwa.edu.au.
authors.forename: Trevor A
authors.initials: TA
authors.lastname: Mori
authors.affiliation: National Centre for Epidemiology and Population Health, The Australian National University, Canberra, Australian Capital Territory, 2600, Australia. laura.king@anu.edu.au.
authors.forename: Laura
authors.initials: L
authors.lastname: King
authors.affiliation: Telethon Kids Institute, The University of Western Australia, Perth, Western Australia, Australia. lucinda.black@telethonkids.org.au.
authors.forename: Lucinda J
authors.initials: LJ
authors.lastname: Black
authors.affiliation: National Centre for Epidemiology and Population Health, The Australian National University, Canberra, Australian Capital Territory, 2600, Australia. Kushani.marshall@anu.edu.au.
authors.forename: Kushani
authors.initials: K
authors.lastname: Marshall
authors.affiliation: National Centre for Epidemiology and Population Health, The Australian National University, Canberra, Australian Capital Territory, 2600, Australia. fan.xiang@anu.edu.au.
authors.forename: Fan
authors.initials: F
authors.lastname: Xiang
authors.affiliation: National Centre for Epidemiology and Population Health, The Australian National University, Canberra, Australian Capital Territory, 2600, Australia. candy.wyatt@gmail.com.|Telethon Kids Institute, The University of Western Australia, Perth, Western Australia, Australia. candy.wyatt@gmail.com.
authors.forename: Candy
authors.initials: C
authors.lastname: Wyatt
authors.affiliation: Australian Radiation Protection and Nuclear Safety Agency, Melbourne, Victoria, Australia. kerryn.king@arpansa.gov.au.
authors.forename: Kerryn
authors.initials: K
authors.lastname: King
authors.affiliation: Cancer Council of Western Australia, Perth, Western Australia, Australia. terry@cancerwa.asn.au.
authors.forename: Terry
authors.initials: T
authors.lastname: Slevin
authors.affiliation: University of Queensland, Brisbane, Queensland, Australia. n.pandeya1@uq.edu.au.
authors.forename: Nirmala
authors.initials: N
authors.lastname: Pandeya
authors.affiliation: National Centre for Epidemiology and Population Health, The Australian National University, Canberra, Australian Capital Territory, 2600, Australia. robyn.lucas@anu.edu.au.|Telethon Kids Institute, The University of Western Australia, Perth, Western Australia, Australia. robyn.lucas@anu.edu.au.
authors.forename: Robyn M
authors.initials: RM
authors.lastname: Lucas
mesh_terms: D000293:Adolescent; D000328:Adult; D001315:Australia / Q000453:epidemiology; D002980:Climate; D019587:Dietary Supplements; D004305:Dose-Response Relationship, Drug; D005260:Female; D006370:Heliotherapy / Q000379:methods*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009520:New Zealand / Q000453:epidemiology; D012107:Research Design; D012307:Risk Factors; D012621:Seasons; D012878:Skin Neoplasms / Q000209:etiology; D013472:Sunlight / Q000009:adverse effects; D014807:Vitamin D / Q000008:administration & dosage / Q000031:analogs & derivatives*; D014808:Vitamin D Deficiency / Q000628:therapy*; D014815:Vitamins / Q000008:administration & dosage*; D055815:Young Adult
chemical_list: D014815:Vitamins; D014807:Vitamin D; C104450:25-hydroxyvitamin D