title: Associations between objective and self-reported physical activity and vitamin D serum levels in the US population.
abstract: OBJECTIVE
  Both low levels of vitamin D and of physical activity are associated with all-cause, cancer, and cardiovascular disease mortality. There is some evidence based on self-reported activity levels that physically more active individuals have higher vitamin D serum levels. The aim was to investigate associations between objectively measured and self-reported physical activity, respectively, and vitamin D serum concentrations in the US population.
  
  
  METHODS
  Data from NHANES 2003-2006 (n = 6,370, aged ≥ 18 years) were analyzed using multiple regression analyses. A total of 6,370 individuals aged 18 years and older with valid data on vitamin D serum levels and physical activity were included. Objective physical activity was assessed using accelerometers; self-reported physical activity was based on the NHANES physical activity questionnaire.
  
  
  RESULTS
  An increase of 10 min of objectively measured and self-reported moderate-to-vigorous activities per day was associated with an increase in circulating vitamin D of 0.32 ng/ml (95% CI 0.17, 0.48) and of 0.18 ng/ml (95% CI 0.12, 0.23), respectively. The odds ratio for being vitamin D deficient (< 20 ng/ml) if being insufficiently active compared with being sufficiently active was 1.32 (1.11, 1.57). Associations were not stronger for self-reported outdoor activities compared with indoor activities.
  
  
  CONCLUSIONS
  Physical activity may be a way to achieve higher vitamin D serum levels in the population. Factors other than sun exposure that may be responsible for higher vitamin D levels in more active individuals need further investigation.
authors: Division of Chronic Disease Epidemiology, Department of Epidemiology, Epidemiology, Biostatistics and Prevention Institute, University of Zurich, Seilergraben 49, 8001, Zurich, Switzerland.
authors: Miriam
authors: M
authors: Wanner
authors: Aline
authors: A
authors: Richard
authors: Brian
authors: B
authors: Martin
authors: Jakob
authors: J
authors: Linseisen
authors: Sabine
authors: S
authors: Rohrmann
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009749:Nutrition Surveys; D057566:Self Report; D011795:Surveys and Questionnaires; D014481:United States; D014807:Vitamin D / Q000097:blood*; D014808:Vitamin D Deficiency / Q000097:blood*; D055815:Young Adult
chemical_list: D014807:Vitamin D