Xiang Fan, Lucas Robyn, de Gruijl Frank, Norval Mary
National Centre for Epidemiology and Population Health, The Australian National University, Canberra, Australia.
Department of Dermatology, Leiden University Medical Centre, P.O. Box 9600, NL-2300 RC Leiden, Netherlands.
Photochem Photobiol Sci. 2015 Dec;14(12):2138-46. doi: 10.1039/c5pp00168d.
Defining whether skin pigmentation influences vitamin D photosynthesis is important for delivering accurate public health messages. Current evidence is contradictory. We undertook a systematic review of the published literature to examine the association between skin pigmentation and change in blood concentrations of vitamin D and 25-hydroxyvitamin D following experimental UV irradiation. Twelve studies fulfilled the inclusion criteria: human study in vivo with non-diseased participants; controlled artificial UV radiation; vitamin D or 25-hydroxyvitamin D measured in serum or plasma; full text in English. In seven studies, vitamin D photosynthesis was reduced in dark-skinned compared with fairer-skinned individuals. In the remaining five studies, only one of which was published after 1990, there was no difference in vitamin D photosynthesis according to skin type. The disparities in these results may be due to small sample sizes and variations in study methodology, including the source, dose and frequency of UV irradiation, phototype classification, and analysis of vitamin D and 25-hydroxyvitamin D. Of these, the spectrum emitted by the UV lamps may be significant. No study considered potential modifying factors, such as relevant genetic polymorphisms. On balance, we conclude that pigmented skin has less effective photoproduction of vitamin D and 25-hydroxyvitamin D. The quantity of sun exposure needed for dark-skinned, compared with light-skinned, people to achieve vitamin D sufficiency remains uncertain.
确定皮肤色素沉着是否会影响维生素D的光合作用对于传递准确的公共卫生信息至关重要。目前的证据相互矛盾。我们对已发表的文献进行了系统综述，以研究皮肤色素沉着与实验性紫外线照射后血液中维生素D和25-羟基维生素D浓度变化之间的关联。十二项研究符合纳入标准：对无疾病参与者进行的人体体内研究；可控的人工紫外线辐射；血清或血浆中维生素D或25-羟基维生素D的测量；英文全文。在七项研究中，与皮肤较白的个体相比，深色皮肤个体的维生素D光合作用降低。在其余五项研究中，只有一项是1990年以后发表的，根据皮肤类型，维生素D光合作用没有差异。这些结果的差异可能是由于样本量小以及研究方法的差异，包括紫外线照射的来源、剂量和频率、光型分类以及维生素D和25-羟基维生素D的分析。其中，紫外线灯发出的光谱可能很重要。没有研究考虑潜在的修饰因素，如相关的基因多态性。总体而言，我们得出结论，色素沉着皮肤产生维生素D和25-羟基维生素D的光反应效率较低。与浅肤色人群相比，深肤色人群达到维生素D充足所需的日照量仍不确定。
