In our practice on prescription to all: Adults, Teenagers over 12: weekly 500 mcg (= 20,000 IU) Children aged 5 - 12: daily 25 mcg (= 1,000 IU) Children aged 0 - 5: daily 10 mcg (= 400 IU) Pregnant women: daily 50 mcg (= 2,000 IU)