title: Smoking and serum vitamin D in older Chinese people: cross-sectional analysis based on the Guangzhou Biobank Cohort Study.
abstract: Studies on serum vitamin D in smokers showed conflicting results. We examined the association of smoking status with serum vitamin D in older Chinese men, taking advantage of a community-based sample with natural exposure to vitamin D.
  
  
  
  Cross-sectional study based on the Guangzhou Biobank Cohort Study (GBCS).
  
  
  
  Community-based sample from the Guangzhou Biobank Cohort Study.
  
  
  
  612 male participants aged 50+years recruited from 2009 to 2011.
  
  
  
  The mean (SD) of vitamin D concentration was 58.3 (17.2), 57.0 (15.0) and 54.7 (15.4) nmol/L for never, former and current smokers, respectively. Adjusted for multiple confounders, vitamin D decreased from never to former, then to current smokers (P for trend 0.02). Compared to never smokers, current smokers had lower serum concentrations of vitamin D, and the concentrations decreased with the increasing number of cigarettes per day (-3.11 (95% CI -9.05 to 2.82), -3.29 (-8.3 to 1.72) and -4.61 (-8.89 to -0.33) for 1-9, 10-19 and 20+cigarettes per day, respectively; p for trend 0.01), duration of smoking (-1.39 (-6.09 to 3.30) and -5.39 (-9.42 to -1.35) for 1-39 and 40+years, respectively; p for trend 0.008) as well as pack-years (-2.89 (-6.78 to 1.01) and -5.58 (-10.48 to -0.67) for 1-39 and 40+pack-years, respectively; p for trend 0.009). Longer duration of quitting smoking was associated with higher vitamin D than was current smoking (P for trend 0.04).
  
  
  
  Current smokers had lower vitamin D than never smokers, and the association showed a dose-response pattern.
authors.affiliation: Guangzhou No 12 Hospital, Guangzhou, China.
authors.forename: C Q
authors.initials: CQ
authors.lastname: Jiang
authors.affiliation: Division of Cardiology, Department of Medicine, Queen Mary Hospital, the University of Hong Kong, Hong Kong, China.
authors.forename: Y H
authors.initials: YH
authors.lastname: Chan
authors.affiliation: School of Public Health, the University of Hong Kong, Hong Kong, China.
authors.forename: L
authors.initials: L
authors.lastname: Xu
authors.affiliation: Guangzhou No 12 Hospital, Guangzhou, China.
authors.forename: Y L
authors.initials: YL
authors.lastname: Jin
authors.affiliation: Guangzhou No 12 Hospital, Guangzhou, China.
authors.forename: T
authors.initials: T
authors.lastname: Zhu
authors.affiliation: Guangzhou No 12 Hospital, Guangzhou, China.
authors.forename: W S
authors.initials: WS
authors.lastname: Zhang
authors.affiliation: Institute of Applied Health Research, University of Birmingham, Birmingham, UK.
authors.forename: K K
authors.initials: KK
authors.lastname: Cheng
authors.affiliation: Division of Cardiology, Department of Medicine, Queen Mary Hospital, the University of Hong Kong, Hong Kong, China.
authors.forename: T H
authors.initials: TH
authors.lastname: Lam
mesh_terms: D000368:Aged; D044466:Asian People; D018070:Biological Specimen Banks; D002681:China; D000073865:Cigarette Smoking / Q000097:blood*; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D012044:Regression Analysis; D012307:Risk Factors; D014807:Vitamin D / Q000097:blood*
chemical_list: D014807:Vitamin D
keywords: Older people; Smoking; Vitamin D