title: Predictors of vitamin D status in subjects that consume a vitamin D supplement.
abstract: OBJECTIVE
  Although dietary supplement use has increased significantly among the general population, the interplay between vitamin D supplementation and other factors that influence vitamin D status remains unclear. The objective of this study was to identify predictor variables of vitamin D status in free-living subjects to determine the extent to which vitamin D supplements and other factors influence vitamin D status.
  
  
  METHODS
  This was a retrospective, cross-sectional study involving 743 volunteers. Serum 25-hydroxy-vitamin D (25(OH)D) level and the variables diet, supplement usage, latitude of residence, ethnicity, age and body mass index (BMI) were used to predict vitamin D status in a summer and winter cohort.
  
  
  RESULTS
  Supplemental vitamin D3 consumption was the most significant positive predictor, whereas BMI was the most significant negative predictor, of vitamin D status in each cohort. Other positive predictors were fortified beverage and dairy consumption in the summer and winter cohort, respectively. Negative predictors were: African American, Asian and Hispanic race in the summer; latitude of residence >36°N, Asian and Hispanic ethnicity in the winter. Mean(± s.d.) 25(OH)D levels were 101.1 (± 42.1) and 92.6 (± 39.0) nmol/l in summer and winter, respectively. Comparing non-supplement vs supplement users, approximately 38 vs 2.5% in the winter and 18 vs 1.4% in the summer had vitamin D levels <50 nmol/l.
  
  
  CONCLUSIONS
  Vitamin D supplementation was the most significant positive predictor of vitamin D status. Collectively, these data point to the practicality of utilizing vitamin D supplements to reduce hypovitaminosis D in adults throughout the United States.
authors.affiliation: USANA Health Sciences, Inc. 3838 West Parkway Blvd; Salt Lake City, UT, USA.
authors.forename: M A
authors.initials: MA
authors.lastname: Levy
authors.affiliation: USANA Health Sciences, Inc. 3838 West Parkway Blvd; Salt Lake City, UT, USA.
authors.forename: T
authors.initials: T
authors.lastname: McKinnon
authors.affiliation: The Orthopedic Specialty Hospital, 5848 South Fashion Blvd; Murray, KY, USA.
authors.forename: T
authors.initials: T
authors.lastname: Barker
authors.affiliation: USANA Health Sciences, Inc. 3838 West Parkway Blvd; Salt Lake City, UT, USA.
authors.forename: A
authors.initials: A
authors.lastname: Dern
authors.affiliation: USANA Health Sciences, Inc. 3838 West Parkway Blvd; Salt Lake City, UT, USA.
authors.forename: T
authors.initials: T
authors.lastname: Helland
authors.affiliation: USANA Health Sciences, Inc. 3838 West Parkway Blvd; Salt Lake City, UT, USA.
authors.forename: J
authors.initials: J
authors.lastname: Robertson
authors.affiliation: USANA Health Sciences, Inc. 3838 West Parkway Blvd; Salt Lake City, UT, USA.
authors.forename: J
authors.initials: J
authors.lastname: Cuomo
authors.affiliation: USANA Health Sciences, Inc. 3838 West Parkway Blvd; Salt Lake City, UT, USA.
authors.forename: T
authors.initials: T
authors.lastname: Wood
authors.affiliation: USANA Health Sciences, Inc. 3838 West Parkway Blvd; Salt Lake City, UT, USA.
authors.forename: B M
authors.initials: BM
authors.lastname: Dixon
mesh_terms: D000328:Adult; D001741:Black or African American; D000368:Aged; D001213:Asian; D015992:Body Mass Index; D002762:Cholecalciferol / Q000008:administration & dosage; D003430:Cross-Sectional Studies; D003611:Dairy Products; D004032:Diet; D019587:Dietary Supplements; D005006:Ethnicity; D005260:Female; D006630:Hispanic or Latino; D006801:Humans; D008019:Life Style; D008297:Male; D008875:Middle Aged; D009752:Nutritional Status; D012189:Retrospective Studies; D012621:Seasons; D014481:United States / Q000453:epidemiology; D014807:Vitamin D / Q000008:administration & dosage* / Q000031:analogs & derivatives / Q000097:blood*; D014808:Vitamin D Deficiency / Q000453:epidemiology*
chemical_list: D014807:Vitamin D; D002762:Cholecalciferol; C104450:25-hydroxyvitamin D