After doing zinc and drinking lemon juice/ acv for a couple of days, didn't see very much improvement. When i added jojoba oil and zinc, well that made a hell of a difference to healing acne. Not quite sure why, but jojoba and zinc oxide worked quite well to heal bad red spots. I am not sure, however, the effectiveness of preventing acne. But, this helped me dramatically. Maybe its only once in a while that you can do this. Not quite sure. There are so many variables!
Just thought you would appreciate the update. good luck!