title: Interaction of Vitamin D and Smoking on Inflammatory Markers in the Urban Elderly.
abstract: OBJECTIVE
  Epidemiological studies have reported that vitamin D deficiency is associated with inflammatory disease. Smoking is a well-known risk factor for inflammation. However, few studies have investigated the interactive effect of vitamin D deficiency and smoking on inflammation. This study aims to investigate the interaction of vitamin D and smoking with inflammatory markers in the urban elderly.
  
  
  METHODS
  We used data from the Korean Elderly Environmental Panel Study, which began in August 2008 and ended in August 2010, and included 560 Koreans ≥60 years old living in Seoul. Data was collected via questionnaires that included items about smoking status at the first visit. Vitamin D levels, high-sensitivity C-reactive protein (hs-CRP), and white blood cell (WBC) counts were repeatedly measured up to three times.
  
  
  RESULTS
  The association of vitamin D and hs-CRP was significant after adjusting for known confounders (β=-0.080, p=0.041). After separate analysis by smoking status, the association of vitamin D deficiency and hs-CRP in smokers was stronger than that in nonsmokers (smokers: β=-0.375, p=0.013; non-smokers: β=-0.060, p=0.150). Smoking status was an effect modifier that changed the association between vitamin D deficiency and hs-CRP (interaction estimate: β=-0.254, p=0.032). Vitamin D was not significantly associated with WBC count (β=0.003, p=0.805).
  
  
  CONCLUSIONS
  Vitamin D deficiency was associated with hs-CRP in the urban elderly. Smoking status was an effect modifier of this association. Vitamin D deficiency was not significantly associated with WBC count.
authors.affiliation: Department of Preventive Medicine, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Hyemi
authors.initials: H
authors.lastname: Lee
authors.affiliation: Department of Preventive Medicine, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Kyoung-Nam
authors.initials: KN
authors.lastname: Kim
authors.affiliation: Environmental Health Center, Seoul National University College of Medicine, Seoul, Korea ; Institute of Environmental Medicine, Seoul National University Medical Research Center, Seoul, Korea.
authors.forename: Youn-Hee
authors.initials: YH
authors.lastname: Lim
authors.affiliation: Department of Preventive Medicine, Seoul National University College of Medicine, Seoul, Korea ; Environmental Health Center, Seoul National University College of Medicine, Seoul, Korea ; Institute of Environmental Medicine, Seoul National University Medical Research Center, Seoul, Korea.
authors.forename: Yun-Chul
authors.initials: YC
authors.lastname: Hong
mesh_terms: D015652:25-Hydroxyvitamin D 2 / Q000097:blood; D000368:Aged; D015415:Biomarkers / Q000097:blood; D015992:Body Mass Index; D002097:C-Reactive Protein / Q000032:analysis; D005260:Female; D006801:Humans; D007249:Inflammation; D007958:Leukocyte Count; D008297:Male; D008875:Middle Aged; D012907:Smoking; D014505:Urban Population; D014807:Vitamin D / Q000097:blood*; D014808:Vitamin D Deficiency / Q000175:diagnosis
chemical_list: D015415:Biomarkers; D014807:Vitamin D; D015652:25-Hydroxyvitamin D 2; D002097:C-Reactive Protein
keywords: 25-Hydroxyvitamin D2; C-reactive protein; Inflammation; Leukocytes; Smoking; Vitamin D