Effects of nutritional supplements on aggression, rule‐breaking, and psychopathology among young adult prisoners

Objective : In an earlier study, improvement of dietary status with food supplements led to a reduction in antisocial behavior among prisoners. Based on these earlier findings, a study of the effects of food supplements on aggression, rule‐breaking, and psychopathology was conducted among young Dutch prisoners. Methods : Two hundred and twenty‐one young adult prisoners (mean age=21.0, range 18–25 years) received nutritional supplements containing vitamins, minerals, and essential fatty acids or placebos, over a period of 1–3 months. Results : As in the earlier (British) study, reported incidents were significantly reduced ( P =.017, one‐tailed) in the active condition ( n =115), as compared with placebo ( n =106). Other assessments, however, revealed no significant reductions in aggressiveness or psychiatric symptoms. Conclusion : As the incidents reported concerned aggressive and rule‐breaking behavior as observed by the prison staff, the results are considered to be promising. However, as no significant improvements were found in a number of other (self‐reported) outcome measures, the results should be interpreted with caution. Aggr. Behav. 36:117–126, 2010. © 2009 Wiley‐Liss, Inc.