I'm sure there are many factors. At one point while very sick and homeless, I was coming across like a bipolar person to some degree. I did some research and adjusted my diet to shut that down.

I imagine that poverty and poor diet do all kinds of bad things to the populations that tend to be most at risk of ending up in jail in the US. I have at times fantasized about trying to do something about nutrition in the US prison system as a means of trying to break the cycle, but I'm probably never going to be in a position to do that.

Even the Bible posits that feeding people is the way to promote the peace, basically. Psychological research and firsthand experience suggest that's pretty sound as an approach.

Edit: See discussion here:

https://news.ycombinator.com/item?id=16140867