title: Determinants of plasma 25-hydroxyvitamin D levels in healthy adults in the Netherlands.
abstract: BACKGROUND
  Vitamin D plays a key role in maintaining skeletal health, but is also related to various non-skeletal health issues. Several determinants have been identified that influence blood plasma levels of 25-hydroxyvitamin D (25(OH) D), often in specific patients or elderly populations. This paper aims to replicate these findings in a healthy population.
  
  
  METHODS
  Plasma levels of 25(OH)D were measured using tandem mass spectrometry. We examined the cross-sectional association of sociodemographic, health, lifestyle and sampling characteristics with 25(OH)D in a group of 539 adults, who were healthy control subjects in the NESDA study in the Netherlands (latitude 52 °N).
  
  
  RESULTS
  Mean 25(OH)D levels were 68.0 (± 27.2) nmol/l. Levels under 50 nmol/l occurred in 27% of the population; 40% reached levels above 75 nmol/l. Women had higher levels than men, and the use of oral contraceptives showed a significant positive association among females. Subjects with non-European ancestry had dramatically lower 25(OH) D levels. Other factors that were negatively associated were body mass index and the renal estimated glomerular filtration rate (eGFR). Meteorological data replaced season as a significant determinant. Moderate alcohol consumption and sports showed a positive association, while physical activity and the hepatic marker gamma-glutamyl transferase did not. Our results disconfirm the influence of age in this population of under 65 year olds.
  
  
  CONCLUSIONS
  Insufficient 25(OH)D levels were common in a healthy population. The set of eight variables that were significant in a multiple regression model (sex, ancestry, oral contraceptives, eGFR, BMI, sports, alcohol, sunshine) explained 29.5% of the variance.
authors.affiliation: GGZ inGeest and Department of Psychiatry, EMGO+ Institute and Neuroscience Campus Amsterdam, VU University Medical Center, the Netherlands.
authors.forename: G
authors.initials: G
authors.lastname: van Grootheest
authors.forename: Y
authors.initials: Y
authors.lastname: Milaneschi
authors.forename: P T A M
authors.initials: PT
authors.lastname: Lips
authors.forename: A C
authors.initials: AC
authors.lastname: Heijboer
authors.forename: J H
authors.initials: JH
authors.lastname: Smit
authors.forename: B W J H
authors.initials: BW
authors.lastname: Penninx
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008019:Life Style; D008137:Longitudinal Studies; D008297:Male; D013058:Mass Spectrometry; D008875:Middle Aged; D009426:Netherlands / Q000453:epidemiology; D010949:Plasma; D012044:Regression Analysis; D012307:Risk Factors; D017678:Sex Distribution; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood* / Q000453:epidemiology*; D055815:Young Adult
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D