title: Sun-Exposed Skin Color Is Associated with Changes in Serum 25-Hydroxyvitamin D in Racially/Ethnically Diverse Children.
abstract: UVB light from the sun increases serum 25-hydroxyvitamin D [25(OH)D] concentration, but this relation may depend on skin pigmentation among different racial/ethnic groups.
  
  
  
  We used quantitative measures of exposed (facultative) and unexposed (constitutive) skin color to examine relations between serum 25(OH)D concentration, tanning, race/ethnicity, and constitutive skin color over the summer, following winter vitamin D supplementation.
  
  
  
  The subjects (n= 426, mean age 11.7 ± 1.4 y, 51% female) were racially/ethnically diverse schoolchildren (57% non-white/Caucasian) enrolled in a 6-mo vitamin D supplementation trial (October-December to April-June). In this secondary analysis, measures of serum 25(OH)D concentration and skin color, with the use of reflectance colorimetry, were taken over a 6-mo period after supplementation, from pre-summer (April-June) to post-summer (September-December). Multiple linear regression was used to evaluate longitudinal relations.
  
  
  
  Following supplementation, mean serum 25(OH)D concentration was 29.3 ± 9.5 ng/mL but fell to 25.6 ± 7.9 ng/mL (P< 0.0001) by the end of summer. The decrease in white/Caucasian children was less than in black/African American children (P< 0.01) and tended to be less than in Hispanic/Latino, Asian, and multiracial/other children (P= 0.19-0.50) despite similar changes in sun-exposed skin color among all groups. Tanning was significantly associated with post-summer serum 25(OH)D concentration (β = -0.15,P< 0.0001), as was race/ethnicity (P= 0.0002), but the later association disappeared after adjusting for constitutive skin color.
  
  
  
  Tanning significantly contributed to serum 25(OH)D concentration over the summer, independent of race/ethnicity, but was not sufficient to maintain serum 25(OH)D concentration attained with supplementation. Much of the variation in serum 25(OH)D concentration between racial/ethnic groups may be explained by skin color. This trial was registered atclinicaltrials.govasNCT01537809.
authors.affiliation: Friedman School of Nutrition Science and Policy, Tufts University, Boston, MA; caleigh.sawicki@tufts.edu.
authors.forename: Caleigh M
authors.identifier: 0000-0002-8353-3106
authors.initials: CM
authors.lastname: Sawicki
authors.affiliation: Friedman School of Nutrition Science and Policy, Tufts University, Boston, MA;
authors.forename: Maria I
authors.initials: MI
authors.lastname: Van Rompay
authors.affiliation: Nutrition Policy Institute, University of California, Agriculture and Natural Resources, Berkeley, CA; and.
authors.forename: Lauren E
authors.initials: LE
authors.lastname: Au
authors.affiliation: Divisions of Adolescent Medicine and Endocrinology, Hasbro Children's Hospital, Alpert Medical School of Brown University, Providence, RI.
authors.forename: Catherine M
authors.initials: CM
authors.lastname: Gordon
authors.affiliation: Friedman School of Nutrition Science and Policy, Tufts University, Boston, MA;
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: Sacheck
mesh_terms: D000293:Adolescent; D015992:Body Mass Index; D002648:Child; D003430:Cross-Sectional Studies; D019587:Dietary Supplements; D004311:Double-Blind Method; D002149:Energy Intake; D005006:Ethnicity; D015444:Exercise; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D016014:Linear Models; D008297:Male; D044469:Racial Groups; D012307:Risk Factors; D012621:Seasons; D057185:Sedentary Behavior; D012880:Skin Pigmentation; D013472:Sunlight; D014807:Vitamin D / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000097:blood
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D
keywords: colorimetry; dietary supplements; ethnic groups; schoolchildren; skin pigmentation; sun exposure; tanning; vitamin D