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 at 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 (25OHD) 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.