Response to Vitamin D Supplementation during Antarctic Winter Is Related to BMI, and Supplementation Can Mitigate Epstein-Barr Virus Reactivation

Maintaining vitamin D status without sunlight exposure is difficult without supplementation. This study was designed to better understand interrelatiorships between periodic vitamin D supplementation and immune function n Antarctic workers. The effect of 2 oral dosing regimens of vitamin D supplementation on vitamin D status and markers of immune function was evaluated in people in Antarctica with no UV light exposure for 6 mo. Participants were given a 2000-IU (50 mu g) daily (n = 15) or 10.000 IU (250 mu g) weekly (n = 14) vitamin D supplement for 6 mo during a winter in Antarctica. Biological samples were collected at baseline and at 3 and 6 mo. Vitamin D intake, markers of vitamin D and bone metabolism. and latent virus reactivation were determined. After 6 mo, the serum 25-hydroxyvitamin D concentration (mean SD) increased from 56 +/- 17 to 79 +/- 16 mmol/L and from 52 = 10 to 60 +/- 9 nmol/1 in the 2000-IU/d and 10,000-IU/wk groups, respectively (main effect over time, P < 0.001). Participants with a greater BMI (participant BMI range = 19-43 g/m(2)) had a smaller increase in 25-hyd-oxyvitamin D after 6 mo supplementation (P < 0.05). Participants with high serum cortisol and higher serum 25-hydroxyvitamin D were less likely to shed Epstein Barr virus in saliva (P < 0.05). The aoses given raised vitamn D status in participants not exposed to sunlight for 6 mo, and the efficacy was influenced by baseline vitamin D status and BMI. The data also provide evidence trial vitamin D, interacting with stress, can reduce risk of latent virus reactivation during the winter in Antarctica. J. Nutr, 141: 692-697, 2011.