title: Association between serum 25-hydroxyvitamin D concentration and symptoms of respiratory tract infection in a Norwegian population: the Tromsø Study.
abstract: OBJECTIVE
  Previous studies have suggested anti-infection effects of vitamin D, although the associations reported between vitamin D (serum 25-hydroxyvitamin D (25(OH)D) concentration) and respiratory tract infection (RTI) are conflicting. The main aim of the present study was to explore this association in a Norwegian population.
  
  
  METHODS
  We examined the association between serum 25(OH)D and recent RTI symptoms in 6350 middle-aged and elderly participants in the Tromsø Study 6. The main outcome measurement was self-reported RTI symptoms in the previous week.
  
  
  METHODS
  Tromsø, Norway, 69 °N.
  
  
  METHODS
  Six thousand three hundred and fifty middle-aged and elderly residents of Tromsø.
  
  
  RESULTS
  Of the 6350 included, 791 (12.5%) reported RTI symptoms in the previous week. We classified serum 25(OH)D concentrations into quartiles and adjusted the data for current smoking habit and month of attendance. The prevalence of RTI symptoms did not increase with decreasing serum 25(OH)D level, was highest in quartile 3 (15.0%) followed by quartile 4 (12.4%), and was lowest in quartiles 1 and 2 (11.1% and 11.4%). There was no trend for increasing duration of illness with decreasing serum 25(OH)D. The prevalence of RTI symptoms was not significantly associated with the intake of fish, n-3 capsules or vitamin and/or mineral supplements, or sun exposure. Only use of cod-liver oil or fish oil capsules daily or sometimes was significantly associated with fewer RTI symptoms during the preceding 7 d (P = 0.04).
  
  
  CONCLUSIONS
  Low serum 25(OH)D was not associated with increased prevalence of recent RTI symptoms. Our findings do not support the idea that vitamin D supplementation can reduce the incidence of RTI in Norway.
authors: 1 General Practice Research Unit, Department of Community Medicine, MH-building, Faculty of Health Science, University of Tromsø, 9037 Tromsø, Norway.
authors: Steinar
authors: S
authors: Robertsen
authors: 2 Tromsø Endocrine Research Group, Department of Clinical Medicine, Faculty of Health Science, University of Tromsø and Division of Internal Medicine, University Hospital of North Norway, Tromsø, Norway.
authors: Guri
authors: G
authors: Grimnes
authors: 1 General Practice Research Unit, Department of Community Medicine, MH-building, Faculty of Health Science, University of Tromsø, 9037 Tromsø, Norway.
authors: Hasse
authors: H
authors: Melbye
mesh_terms: D000368:Aged; D019587:Dietary Supplements; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009664:Norway / Q000453:epidemiology; D015995:Prevalence; D012141:Respiratory Tract Infections / Q000097:blood* / Q000453:epidemiology* / Q000517:prevention & control; D012307:Risk Factors; D014807:Vitamin D / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000453:epidemiology*
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D
references: Arch Intern Med. 2009 Feb 23;169(4):384-90
references: 19237723
references: Arterioscler Thromb Vasc Biol. 2008 Jun;28(6):1179-85
references: 18417640
references: Proc Nutr Soc. 2012 Feb;71(1):90-7
references: 22115013
references: Eur Respir J. 2005 Aug;26(2):319-38
references: 16055882
references: N Engl J Med. 2007 Jul 19;357(3):266-81
references: 17634462
references: Stroke. 2008 Sep;39(9):2611-3
references: 18635847
references: Arch Intern Med. 2003 Feb 24;163(4):487-94
references: 12588210
references: Eur J Endocrinol. 2010 Aug;163(2):339-48
references: 20479012
references: Am J Epidemiol. 2010 Apr 15;171(8):903-8
references: 20219763
references: J Nutr. 2005 Feb;135(2):310-6
references: 15671233
references: Inflammation. 2012 Jun;35(3):1015-22
references: 22089980
references: Int J Pediatr Otorhinolaryngol. 2011 Mar;75(3):364-7
references: 21215466
references: Arch Intern Med. 2008 Jun 9;168(11):1174-80
references: 18541825
references: N Engl J Med. 1980 Aug 14;303(7):349-54
references: 6248779
references: Am J Clin Nutr. 2004 Dec;80(6 Suppl):1689S-96S
references: 15585789
references: Public Health Nutr. 2012 Nov;15(11):2157-62
references: 22414776
references: South Med J. 2005 Oct;98(10):1024-7
references: 16295817
references: J Public Health (Oxf). 2009 Dec;31(4):512-20
references: 19734168
references: Public Health Nutr. 2004 Apr;7(2):327-35
references: 15003141
references: Br J Nutr. 2011 Nov;106(9):1433-40
references: 21736791
references: Am J Clin Nutr. 2007 Sep;86(3):714-7
references: 17823437
references: Eur Respir J. 2001 Nov;18(5):770-9
references: 11757626
references: J R Coll Gen Pract. 1981 Dec;31(233):746-50
references: 7338870
references: J Occup Environ Med. 2002 Sep;44(9):822-9
references: 12227674
references: Scand J Infect Dis. 2012 Feb;44(2):126-32
references: 22026455
references: Int J Epidemiol. 2012 Aug;41(4):961-7
references: 21422063
references: J Infect Dis. 2010 Sep 1;202(5):809-14
references: 20632889
references: Photochem Photobiol. 2005 Nov-Dec;81(6):1287-90
references: 16354110
references: J Am Diet Assoc. 2011 Apr;111(4):524-7
references: 21443983