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J Nutr. 2016 Apr;146(4):751-7. doi: 10.3945/jn.115.222505. Epub 2016 Mar 2.

Sun-Exposed Skin Color Is Associated with Changes in Serum 25-Hydroxyvitamin D in Racially/Ethnically Diverse Children.

Author information

1
Friedman School of Nutrition Science and Policy, Tufts University, Boston, MA; caleigh.sawicki@tufts.edu.
2
Friedman School of Nutrition Science and Policy, Tufts University, Boston, MA;
3
Nutrition Policy Institute, University of California, Agriculture and Natural Resources, Berkeley, CA; and.
4
Divisions of Adolescent Medicine and Endocrinology, Hasbro Children's Hospital, Alpert Medical School of Brown University, Providence, RI.

Abstract

BACKGROUND:

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.

OBJECTIVE:

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.

METHODS:

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.

RESULTS:

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.

CONCLUSIONS:

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.

KEYWORDS:

colorimetry; dietary supplements; ethnic groups; schoolchildren; skin pigmentation; sun exposure; tanning; vitamin D

PMID:
26936138
PMCID:
PMC4807642
DOI:
10.3945/jn.115.222505
[Indexed for MEDLINE]
Free PMC Article

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