Nutrition Department, University of California, Davis, CA, 95616, USA.
J Nutr. 2010 Mar;140(3):542-50. doi: 10.3945/jn.109.115253. Epub 2010 Jan 6.
Cutaneous cholecalciferol synthesis has not been considered in making recommendations for vitamin D intake. Our objective was to model the effects of sun exposure, vitamin D intake, and skin reflectance (pigmentation) on serum 25-hydroxyvitamin D (25[OH]D) in young adults with a wide range of skin reflectance and sun exposure. Four cohorts of participants (n = 72 total) were studied for 7-8 wk in the fall, winter, spring, and summer in Davis, CA [38.5 degrees N, 121.7 degrees W, Elev. 49 ft (15 m)]. Skin reflectance was measured using a spectrophotometer, vitamin D intake using food records, and sun exposure using polysulfone dosimeter badges. A multiple regression model (R(2) = 0.55; P < 0.0001) was developed and used to predict the serum 25(OH)D concentration for participants with low [median for African ancestry (AA)] and high [median for European ancestry (EA)] skin reflectance and with low [20th percentile, approximately 20 min/d, approximately 18% body surface area (BSA) exposed] and high (80th percentile, approximately 90 min/d, approximately 35% BSA exposed) sun exposure, assuming an intake of 200 iu/d (5 ug/d). Predicted serum 25(OH)D concentrations for AA individuals with low and high sun exposure in the winter were 24 and 42 nmol/L and in the summer were 40 and 60 nmol/L. Corresponding values for EA individuals were 35 and 60 nmol/L in the winter and in the summer were 58 and 85 nmol/L. To achieve 25(OH)D > or =75 nmol/L, we estimate that EA individuals with high sun exposure need 1300 iu/d vitamin D intake in the winter and AA individuals with low sun exposure need 2100-3100 iu/d year-round.
尚未考虑皮肤胆钙化醇合成在维生素 D 摄入量建议中的作用。我们的目的是模拟阳光暴露、维生素 D 摄入量和皮肤反射率（色素沉着）对不同皮肤反射率和阳光暴露的年轻成年人血清 25-羟维生素 D（25[OH]D）的影响。在加利福尼亚州戴维斯市（北纬 38.5 度，西经 121.7 度，海拔 49 英尺[15 米]），4 个队列的参与者（共 72 人）在秋季、冬季、春季和夏季进行了为期 7-8 周的研究。使用分光光度计测量皮肤反射率，使用食物记录测量维生素 D 摄入量，使用聚砜剂量计徽章测量阳光暴露。建立了一个多元回归模型（R2 = 0.55；P < 0.0001），用于预测低（非洲裔祖先中位数）和高（欧洲裔祖先中位数）皮肤反射率以及低（第 20 百分位，约 20 分钟/天，约 18%的体表面积[BSA]暴露）和高（第 80 百分位，约 90 分钟/天，约 35% BSA 暴露）阳光暴露的参与者的血清 25（OH）D 浓度，假设摄入量为 200 iu/d（5ug/d）。冬季低和高阳光暴露的 AA 个体的预测血清 25（OH）D 浓度分别为 24 和 42 nmol/L，夏季分别为 40 和 60 nmol/L。EA 个体的相应值在冬季和夏季分别为 35 和 60 nmol/L，在夏季和夏季分别为 58 和 85 nmol/L。为了达到 25（OH）D >或=75 nmol/L，我们估计高阳光暴露的 EA 个体在冬季需要 1300 iu/d 的维生素 D 摄入，低阳光暴露的 AA 个体全年需要 2100-3100 iu/d。
