In the first 4 months of usage I took from 2IU's per day to 7IU's per day. BTW I never took a day off. The funny thing was that my shoe size was in between a 10.5 and 11 I have always had trouble buying shoes. Now I am an 11, 10.5's are too small. I didn't know that my feet were growing in length until I put on my birkentocks, my toes were starting to creap over the front.