We're going to leave this thread closed, because Hoffer's theories have long since been debunked. Please see his Wikipedia entry for more info:

Abram Hoffer - Wikipedia

If there were easy, simple answers to mental illness (like nutrition or diet being major contributing factors), modern science would've found them by now in scientific, peer-reviewed studies. Since such things have not been found by researchers, I would caution against a person pursuing such treatments as being not evidence-based.

Certainly pursuing good nutrition and exercise are positive things to engage in with any mental illness. But they alone do not cause (or are major contributing causative factors to) mental illness. In the vast majority of people, such activities alone will not be sufficient treatments to help someone with mental illness.