Vitamin D Intake Needed to Maintain Target Serum 25-Hydroxyvitamin D Concentrations in Participants with Low Sun Exposure and Dark Skin Pigmentation Is Substantially Higher Than Current Recommendations

J. Nutr. First published January 6, 2010; doi:10.3945/jn.109.115253

Vol. 140, No. 3, 542-550, March 2010

Laura M. Hall3,5,*, Michael G. Kimlin6, Pavel A. Aronov4, Bruce D. Hammock4, James R. Slusser7, Leslie R. Woodhouse5 and Charles B. Stephensen3,5 lauhall@calpoly.edu.

3 Nutrition Department and; 4 Entomology Department and Cancer Center, University of California, Davis, CA, 95616; 5 USDA Western Human Nutrition Research Center, Davis, CA, 95616; 6 AusSun Research Laboratory, Institute of Biomedical Innovation, Queensland University of Technology, Kelvin Grove, Queensland, 4059, Australia; 7 Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, CO 80523

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° N, 121.7° 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 (R2 = 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, ~20 min/d, ~18% body surface area (BSA) exposed] and high (80th percentile, ~90 min/d, ~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 ?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 .