title: Plasma vitamin D biomarkers and leukocyte telomere length in men.
abstract: OBJECTIVE
  Vitamin D may reduce telomere shortening through anti-inflammatory and anti-cell proliferation mechanisms. In women, higher plasma 25-hydroxyvitamin D (25(OH)D) has been shown to be associated with longer telomere length, but the relationship has not been assessed in men.
  
  
  METHODS
  We conducted a cross-sectional analysis of 25(OH)D, 1,25-dihydroxyvitamin D (1,25(OH)2D) and relative leukocyte telomere length (LTL) among 2483 men [1832 men for 1,25(OH)2D] who were selected as cases and controls in three studies of telomeres and cancer nested within the Health Professionals Follow-up Study. We also genotyped 95 SNPs representing common genetic variation in vitamin D pathway genes. LTL was measured by quantitative PCR, and z-scores within each study were calculated. Associations were assessed by linear as well as logistic regression adjusting for age and other potential confounders.
  
  
  RESULTS
  Age (P-trend < 0.0001), pack-years of smoking (P-trend = 0.04) and body mass index (P-trend = 0.05) were inversely associated with LTL. Neither 25(OH)D nor 1,25(OH)2D was associated with LTL (multivariable-adjusted P-trend 0.69 and 0.41, respectively, for the linear regression model). One SNP in the retinoid X receptor alpha gene was associated with long LTL (P = 0.0003).
  
  
  CONCLUSIONS
  In this cross-sectional study of men, 25(OH)D and 1,25(OH)2D were not associated with relative LTL.
authors.affiliation: Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, 02115, USA.|Program in Genetic Epidemiology and Statistical Genetics, Harvard T.H. Chan School of Public Health, Boston, MA, USA.|Division of Nutritional Epidemiology, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Bettina
authors.initials: B
authors.lastname: Julin
authors.affiliation: Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA, USA.|Division of Public Health Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA, USA.
authors.forename: Irene M
authors.initials: IM
authors.lastname: Shui
authors.affiliation: Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, 02115, USA.|Program in Genetic Epidemiology and Statistical Genetics, Harvard T.H. Chan School of Public Health, Boston, MA, USA.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Prescott
authors.affiliation: Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, 02115, USA.|Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA, USA.|Department of Nutrition, Harvard T.H. Chan School of Public Health, Boston, MA, USA.
authors.forename: Edward L
authors.initials: EL
authors.lastname: Giovannucci
authors.affiliation: Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, 02115, USA. nhidv@channing.harvard.edu.|Program in Genetic Epidemiology and Statistical Genetics, Harvard T.H. Chan School of Public Health, Boston, MA, USA. nhidv@channing.harvard.edu.|Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA, USA. nhidv@channing.harvard.edu.
authors.forename: Immaculata
authors.initials: I
authors.lastname: De Vivo
mesh_terms: D000367:Age Factors; D000368:Aged; D015415:Biomarkers / Q000097:blood*; D015992:Body Mass Index; D003430:Cross-Sectional Studies; D005838:Genotype; D006801:Humans; D007962:Leukocytes / Q000648:ultrastructure*; D008297:Male; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D047490:Retinoid X Receptor alpha / Q000235:genetics; D012907:Smoking; D016615:Telomere / Q000648:ultrastructure*; D059505:Telomere Homeostasis / Q000235:genetics; D059506:Telomere Shortening; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood* / Q000235:genetics
chemical_list: D015415:Biomarkers; D047490:Retinoid X Receptor alpha; D014807:Vitamin D; C097949:1,25-dihydroxyvitamin D; C104450:25-hydroxyvitamin D
keywords: Cross-sectional; Men; Telomeres; Vitamin D; Vitamin D pathway SNPs