I've done some research on Douglas Lab vitamins and, time after time, I read that this brand of vitamins is one of the top scoring brands (9.3 on the score chart). I cannot speak, yet, for the long term effect of a better brand of Vitamin D (I just switched over from another brand that is low scoring, which I had no idea until recently) but I have total confidence in this and all other Douglas Lab vitamins that I've ordered. I had Osteoporosis in the left hip which, thankfully, had reversed to osteopenia as of 2016 and i'm hoping that with my next bone scan in the spring, my numbers will be even better with this higher dose of vitamin D from a superior vitamin brand