The mean concentration was higher in the supplemented group than in the placebo group at 2 months ( 26.4 8.1 vs 18.9 8.1 ng/mL ; P < .0001 ) and also at 6 months ( 26.7 7.6 vs 22.4 7.3 ; P = .003 ) , after adjusting for baseline 25 ( OH ) D , race , gender , pubertal status , dietary vitamin D intake , body mass index , and sunlight exposure .