I followed a candida diet some time back, even taking difulcan tablets (which are usually used by women for yeast infections.) In combatting candida, my Acne did not improve.
I tried accutane and it cured the cystic acne. It was a godsend. A temporary godsend it proved to be as a couple of years later, my Acne came back, but never as bad as before the accutane.
I tried retin a for a few months. The pealing was bad and it makes scars look worse during the time I used it. I eventually gave up on it.
I can't tell you all the things I wasted my money on (zeno, etc.) or methods I tried to use (liver flush, all apple diet, etc.), but I never found anything successful or at least as successful as antibodies.