title: Serum 25-hydroxyvitamin d concentrations and season-specific correlates in Japanese adults.
abstract: BACKGROUND
  Several lines of evidence indicate an important role for vitamin D in the prevention of a range of diseases. Blood vitamin D levels show clear seasonal variation; however, data on the determinants of vitamin D status for each season are limited. We investigated the association between lifestyle and serum vitamin D concentration by season in Japanese workers.
  
  
  METHODS
  Subjects were 312 men and 217 women aged 21 to 67 years who worked in municipal offices in Northern Kyushu, Japan and participated in a periodic checkup in July or November. Multiple linear regression analysis was used to examine the association between serum 25-hydroxivitamin D concentrations and lifestyle factors for each season.
  
  
  RESULTS
  Mean serum 25-hydroxyvitamin D concentration was 27.4 ng/ml (68.4 nmol/L) and 21.4 ng/ml (53.4 nmol/L) for workers surveyed in July and November, respectively (P < 0.001); the prevalence of vitamin D deficiency (<20 ng/ml) was 9.3% and 46.7%, respectively (P < 0.001). In November, dietary vitamin D intake (in both sexes) and nonsmoking and physical activity (in men) were significantly associated with higher concentrations of serum 25-hydroxyvitamin D. In summer, fish/shellfish intake was associated with higher serum 25-hydroxyvitamin D concentrations in women.
  
  
  CONCLUSIONS
  Vitamin D deficiency is common in Japanese workers during seasons with limited sunlight. The lifestyle correlates of favorable vitamin D status in November were physical activity, dietary vitamin D intake, and nonsmoking.
authors: Department of Epidemiology and Prevention, International Clinical Research Center, National Center for Global Health and Medicine.
authors: Akiko
authors: A
authors: Nanri
authors: Leng Huat
authors: LH
authors: Foo
authors: Kazutoshi
authors: K
authors: Nakamura
authors: Ai
authors: A
authors: Hori
authors: Kalpana
authors: K
authors: Poudel-Tandukar
authors: Yumi
authors: Y
authors: Matsushita
authors: Tetsuya
authors: T
authors: Mizoue
mesh_terms: D000328:Adult; D000368:Aged; D004651:Employment / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D007564:Japan; D008019:Life Style; D008297:Male; D008875:Middle Aged; D009786:Occupational Health Services; D012307:Risk Factors; D012621:Seasons; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000175:diagnosis*; D055815:Young Adult
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D