Better nutrition would help a whole lot. It is more effective and more humane than the drugs we prefer. If psychoactive drugs help a mental health issue, you can assume it has medical roots for at least a portion of the problem. Treating the medical roots, which can include various infections, is a good path forward.
There used to be an article online called "Diseases of the mind." One thing it talked about: When antibiotics were invented, thousands of people in asylums were successfully treated for syphilis and then set free. Another point it made: Mental illness tends to occur in demographic clusters exactly like infectious disease, which implies it might actually be due to infectious disease.
Let me suggest this for a little related reading:
https://news.ycombinator.com/item?id=16140867
Edit: This is what I am working on:
http://pocketputer.com
Being homeless and helpless is crazy-making. I want to help people start making money, setting goals, etc while still homeless, like I did.
Video from The Loneliness Project:
https://www.youtube.com/watch?v=IYc85A8f2CM
It's aimed at the issue if isolation in the elderly. Homeless people also suffer from social isolation.
It's late. I'm tired. I will add that not all personal problems are about being crazy. Some people have learning disabilities or other barriers to regular employment.
I feel like this answer really sucks because of the framing of the problem in this subthread. I have tried to answer your actual question, which is a legitimate question, but I think the problem is more complicated than that.
:/