In Nutrition and crime? Sounds way too good to be true, Steven Levitt cites a fascinating article:
The researchers then tallied the number of times the participants violated prison rules, and compared it to the same data that had been collected in the months leading up to the nutrition study. The prisoners given supplements for four consecutive months committed an average of 26 percent fewer violations compared to the preceding period. Those given placebos showed no marked change in behaviour. For serious breaches of conduct, particularly the use of violence, the number of violations decreased 37 percent for the men given nutrition supplements, while the placebo group showed no change.
Theodore Dalrymple’s The Starving Criminal makes a similar observation, noting that members of the criminal underclass rarely sit down to dinner, often go without food while on drugs, and even consider prison a good opportunity to fatten back up before hitting the streets again.