title: Sunlight and other determinants of circulating 25-hydroxyvitamin D levels in black and white participants in a nationwide U.S. study.
abstract: Circulating 25-hydroxyvitamin D (25(OH)D), a marker for vitamin D status, is associated with bone health and possibly cancers and other diseases; yet, the determinants of 25(OH)D status, particularly ultraviolet radiation (UVR) exposure, are poorly understood. Determinants of 25(OH)D were analyzed in a subcohort of 1,500 participants of the US Radiologic Technologists (USRT) Study that included whites (n = 842), blacks (n = 646), and people of other races/ethnicities (n = 12). Participants were recruited monthly (2008-2009) across age, sex, race, and ambient UVR level groups. Questionnaires addressing UVR and other exposures were generally completed within 9 days of blood collection. The relation between potential determinants and 25(OH)D levels was examined through regression analysis in a random two-thirds sample and validated in the remaining one third. In the regression model for the full study population, age, race, body mass index, some seasons, hours outdoors being physically active, and vitamin D supplement use were associated with 25(OH)D levels. In whites, generally, the same factors were explanatory. In blacks, only age and vitamin D supplement use predicted 25(OH)D concentrations. In the full population, determinants accounted for 25% of circulating 25(OH)D variability, with similar correlations for subgroups. Despite detailed data on UVR and other factors near the time of blood collection, the ability to explain 25(OH)D was modest.
authors.affiliation: Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland 20892-7238, USA. mf101e@nih.gov
authors.forename: D Michal
authors.initials: DM
authors.lastname: Freedman
authors.forename: Elizabeth K
authors.initials: EK
authors.lastname: Cahoon
authors.forename: Preetha
authors.initials: P
authors.lastname: Rajaraman
authors.forename: Jacqueline M
authors.initials: JM
authors.lastname: Major
authors.forename: Michele M
authors.initials: MM
authors.lastname: Doody
authors.forename: Bruce H
authors.initials: BH
authors.lastname: Alexander
authors.forename: Richard W
authors.initials: RW
authors.lastname: Hoffbeck
authors.forename: Michael G
authors.initials: MG
authors.lastname: Kimlin
authors.forename: Barry I
authors.initials: BI
authors.lastname: Graubard
authors.forename: Martha S
authors.initials: MS
authors.lastname: Linet
mesh_terms: D001741:Black or African American; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000097:blood; D015992:Body Mass Index; D015331:Cohort Studies; D004032:Diet; D019587:Dietary Supplements / Q000706:statistics & numerical data; D015444:Exercise; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D012621:Seasons; D013472:Sunlight; D011795:Surveys and Questionnaires; D014466:Ultraviolet Rays; D014481:United States; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000208:ethnology / Q000209:etiology*; D044465:White People
chemical_list: D015415:Biomarkers; D014807:Vitamin D; C104450:25-hydroxyvitamin D