I have a serious medical condition that makes it difficult to get the nutrients I need. I fairly often have somatopsychic side effects from this. I resolve those issues by figuring out what nutrient I need extra of.

The incident that caused me to think that nutrition should be part of prison rehab was one where I was just inexplicably mad as hell and we resolved it by feeding me an orange every day for the vitamin C. I was like "Holy cow! I bet just getting the right nutrients into prisoners would make them less prone to violence and other problem behaviors."

So as a wild guess: This is probably a significant factor.