Sawicki Caleigh M, Van Rompay Maria I, Au Lauren E, Gordon Catherine M, Sacheck Jennifer M
Friedman School of Nutrition Science and Policy, Tufts University, Boston, MA;
Nutrition Policy Institute, University of California, Agriculture and Natural Resources, Berkeley, CA; and.
J Nutr. 2016 Apr;146(4):751-7. doi: 10.3945/jn.115.222505. Epub 2016 Mar 2.
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.
来自太阳的紫外线B（UVB）可提高血清25-羟基维生素D[25(OH)D]浓度，但这种关系可能因不同种族/族裔群体的皮肤色素沉着而有所不同。
我们使用定量测量暴露（适应性）和未暴露（先天性）皮肤颜色的方法，来研究冬季补充维生素D后，夏季血清25(OH)D浓度、晒黑、种族/族裔和先天性皮肤颜色之间的关系。
研究对象为426名（平均年龄11.7±1.4岁，51%为女性）种族/族裔多样的学童（57%为非白人/高加索人），他们参加了一项为期6个月的维生素D补充试验（10月至12月至次年4月至6月）。在这项二次分析中，在补充维生素D后的6个月期间，即从夏季前（4月至6月）到夏季后（9月至12月），使用反射比色法测量血清25(OH)D浓度和皮肤颜色。采用多元线性回归评估纵向关系。
补充维生素D后，血清25(OH)D平均浓度为29.3±9.5 ng/mL，但到夏季末降至25.6±7.9 ng/mL（P<0.0001）。白人/高加索儿童的下降幅度小于黑人/非裔美国儿童（P<0.01），并且尽管所有组中暴露于阳光的皮肤颜色变化相似，但白人/高加索儿童的下降幅度往往小于西班牙裔/拉丁裔、亚裔和多种族/其他儿童（P=0.19-0.50）。晒黑与夏季后血清25(OH)D浓度显著相关（β=-0.15，P<0.0001），种族/族裔也是如此（P=0.0002），但在调整先天性皮肤颜色后，后一种关联消失。
晒黑在夏季对血清25(OH)D浓度有显著贡献，与种族/族裔无关，但不足以维持补充维生素D后达到的血清25(OH)D浓度。种族/族裔群体之间血清25(OH)D浓度的大部分差异可能由皮肤颜色来解释。本试验已在clinicaltrials.gov上注册，注册号为NCT01537809。
