Has he made other lifestyle changes at the same time as the diet change? Like stopped drinking/smoking/drugs? Good sleep hygeine? Low stress lifestyle? Yoga? Exercise?

I'm asking because it could be these other things (especially exercise, low stress, good sleep, and no alcohol/drugs) that could be the real key to his success. Generally when people become vegan, they make a whole host of other lifestyle changes at the same time. They just start living healthier over-all and become very conscious of what they put in their body.

So, I'm not convinced that going vegan will help with bipolar. But changing your entire life around so that you are eating right, exercising, sleeping right, and minimizing stress? Absolutely, that can have a HUGE effect.

Unforuntanetely, many people with mental illness don't have the motivation/energy to make any of these changes without being on meds. But if you can muster the motivation to eat right and exercise without being on meds, and if you can sleep 8 hours every night without meds....then by all means do it. I don't doubt you will notice a huge improvement in your moods.

One more thing...please make sure you discontue the zoloft first, and then the abilify. You don't want to be on Zoloft unapposed....it could send you completely manic in a very bad way.