Yes I've been since I was diagnosed in '07 I'm taking an average of 40.000ui a week and it has helped me a lot when I was in my first stage of Myasthenia Ocular, in spring of April 2015 I had a CRISIS/FLARE and was hospitalized for 8 weeks and since have to do Plasmaphereris weekly plus Imuran and Mestinon and other meds....I'm still taking vitamin D3 which I think is still good for me at this time.