title: Weight and skin colour as predictors of vitamin D status: results of an epidemiological investigation using nationally representative data.
abstract: OBJECTIVE
  Current US dietary recommendations for vitamin D vary by age. Recent research suggests that body weight and skin colour are also major determinants of vitamin D status. The objective of the present epidemiological investigation was to clarify the role of age as a predictor of vitamin D status, while accounting for body weight and skin colour, among a nationally representative sample.
  
  
  METHODS
  We calculated the mean serum 25-hydroxyvitamin D levels for the US population by age and weight, as well as by weight and race/ethnicity group. Multiple regression analyses were utilized to evaluate age and weight as predictors of vitamin D status: serum 25-hydroxyvitamin D levels with age alone, age and body weight, and age, body weight and their two-way interaction were modelled for the entire sample and each age subgroup. Graphical data were developed using B-spline non-linear regression.
  
  
  METHODS
  National Health and Nutrition Examination Survey (31 934 unweighted cases).
  
  
  METHODS
  Individuals aged 1 year and older.
  
  
  RESULTS
  There were highly significant differences in mean vitamin D status among US residents by weight and skin colour, with those having darker skin colour or higher body weight having worse vitamin D status. Although a significant factor, the impact of age on vitamin D status was notably less than the impact of body weight.
  
  
  CONCLUSIONS
  Vitamin D status varied predominantly by body weight and skin colour. Recommendations by nutritionists for diet and supplementation needs should take this into account if vitamin D-related health disparities are to be meaningfully reduced across the USA.
authors: 1Department of Health and Behavior Studies,Teachers College,Columbia University,525 West 120th Street,New York,NY 10027,USA.
authors: Sonali
authors: S
authors: Rajan
authors: 1Department of Health and Behavior Studies,Teachers College,Columbia University,525 West 120th Street,New York,NY 10027,USA.
authors: Tom
authors: T
authors: Weishaar
authors: 2Department of Human Development,Teachers College,Columbia University,New York,NY,USA.
authors: Bryan
authors: B
authors: Keller
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001835:Body Weight; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D009749:Nutrition Surveys / Q000706:statistics & numerical data*; D012880:Skin Pigmentation; D014481:United States / Q000453:epidemiology; D014807:Vitamin D / Q000097:blood*; D014808:Vitamin D Deficiency / Q000097:blood* / Q000453:epidemiology*; D055815:Young Adult
chemical_list: D014807:Vitamin D
keywords: Epidemiology; RDA; Supplements; Vitamin D