After 6 months, mean serum 25(OH)D increased to 53 nmol/l with 800 IU/day, to 50.5 nmol/l with 100,000 IU/3 months, and to 29.1 nmol/l with advised sunlight exposure (supplementation vs sunshine p < 0.001).
D3 supplementation (daily 800 IU or 100,000 IU/3 months)
sunlight exposure
mean serum 25(OH)D