Pereira Luiza Alonso, Luz Flávio Barbosa, Carneiro Clívia Maria Moraes de Oliveira, Xavier Ana Lucia Rampazzo, Kanaan Salim, Miot Hélio Amante
Department of Dermatology, Universidade Federal Fluminense, Niterói (RJ), Brasil.
Discipline of Dermatology, Department of Dermatology, Universidade Federal Fluminense, Niterói (RJ), Brasil.
An Bras Dermatol. 2019 Jan-Feb;94(1):56-61. doi: 10.1590/abd1806-4841.20198070.
Most of the organism's vitamin D (VD) is obtained through the cutaneous synthesis after exposure to the sun's UVB radiation. Sunscreens are indicated for the prevention of actinic damage to the skin, however, there are few clinical trials assessing the synthesis of cutaneous VD in real-life situations of sun exposure with ordinary clothing and usual photoprotection.
To evaluate the synthesis of VD with suberythemal sun exposure in healthy adults using topical photoprotection (SPF 30).
Quasi-experimental study, conducted at Rio de Janeiro (Brazil), during winter, with 95 healthy adults who had 25-OH-VD checked twice, 24 hours apart, and were exposed to the sun (UVB=20 mJ/cm2), according to a randomized grouping: SC - use of SPF 30 on the face, neck and chest (n=64), NO - no sunscreens (n=10), CO - confined from sun exposure for 24h (n=21). The groups were matched according to the propensity score related to gender, age, phototype, body mass index, glycosylated hemoglobin and baseline levels of VD. The outcome evaluated was the variation (ΔVD) in serum level of 25-OH-VD (ng/ml) between the groups.
A statistically significant difference was identified between CO and SC groups [median (p25-p75)]: ΔVD =1.4 (-0.3-3.6) vs. 5.5 (4.8-6.6); p<0.01. There was no difference between SC and NO groups: 5.4 (3.1-6.1) vs. 4.1 (2.5-6.0); p=0.17.
Laboratory analysis technique (chemiluminescence) with great variability, loss of food intake standardatization, unbalanced groups.
Suberythemal sun exposure with sunscreen (SPF 30) provides similar vitamin D serum variation than without photoprotection in healthy adults.
机体的大部分维生素D（VD）是在暴露于太阳紫外线B（UVB）辐射后通过皮肤合成获得的。防晒霜用于预防皮肤光化性损伤，然而，很少有临床试验评估在穿着普通衣物并采取常规光防护措施的实际日光暴露情况下皮肤VD的合成情况。
使用局部光防护（防晒系数30）评估健康成年人在亚红斑量日光暴露下VD的合成情况。
在巴西里约热内卢进行的一项准实验研究，研究时间为冬季，95名健康成年人参与，他们的25-羟基维生素D（25-OH-VD）水平在间隔24小时的情况下接受了两次检测，并根据随机分组接受日光暴露（UVB=20 mJ/cm2）：SC组——在面部、颈部和胸部使用防晒系数30的防晒霜（n=64），NO组——不使用防晒霜（n=10），CO组——24小时避免日光暴露（n=21）。根据与性别、年龄、皮肤类型、体重指数、糖化血红蛋白和VD基线水平相关的倾向得分对各组进行匹配。评估的结果是各组之间血清25-OH-VD水平（ng/ml）的变化（ΔVD）。
在CO组和SC组之间发现了统计学上的显著差异[中位数（第25百分位数-第75百分位数）]：ΔVD =1.4（-0.3-3.6）与5.5（4.8-6.6）；p<0.01。SC组和NO组之间没有差异：5.4（3.1-6.1）与4.1（2.5-6.0）；p=0.17。
实验室分析技术（化学发光法）变异性大、食物摄入量标准化缺失、各组不均衡。
在健康成年人中，使用防晒霜（防晒系数30）进行亚红斑量日光暴露所导致的血清维生素D变化与不采取光防护措施时相似。
