Nutritional supplements containing vitamins, minerals, omega-3 and omega-6 fatty acids were associated with a 34 per cent reduction in violent incidents, according to findings of a randomized, double-blind, placebo controlled trial with over 200 young adult offenders published in Aggressive Behavior.
On the other hand, a 14 per cent increase in the number of reported incidents in participants in the placebo group were reported by the Dutch scientists, led by Ap Zaalberg from the Dutch Ministry of Justice.
“The prospect of influencing aggression and rule-breaking behavior with nutrients in moderate doses is important enough to warrant further research,” wrote the researchers. “This is particularly true as adequate supplementation may also have beneficial effects on mental health and cognitive functioning.”
Despite the reductions in violent incidents, which were documented by the prison staff, no significant differences were reported by the prisoners themselves when asked to rate their aggression or general health.
“Yet, the results in terms of a substantial reduction in reported incidents seem promising, as this outcome measure in particular may have practical relevance,” wrote Zaalberg and co-workers.
Commenting independently on the research, Professor Michael Crawford, director of the Institute of Brain Chemistry and Human Nutrition at London Metropolitan University told NutraIngredients that the study follows on from a study in England by Bernard Gesch at Oxford University (Br J Psychiat, 2002, Vol. 181, pp 22-28) which found that supplementation of young violent offenders with fatty acids and micronutrients reduced violent offences by some 39 per cent or more.
Dr Gesch’s study was a double blind, placebo-controlled clinical trial, which used the outcome measure was that used by the UK Home Office and Prisons to assess behaviour for legal purposes such as parole. “The measures were pretty robust,” said Prof Crawford.
The area of fatty acid supplementation and aggression was described as “an important development, and about to become more important”, by Prof Jack Winkler, director of the Nutrition Policy Unit at London Metropolitan University.
Talking to NutraIngredients, Prof Winkler said the Zaalberg study extended the data of Gesch and confirms the basic finding: “A good diet reduces aggression,” he said.
With only 200 subjects, the Dutch study would still be classed as small, said Prof Winkler, and “sceptics” have already “nit-picked it on methodological grounds”.
Answers may be forthcoming, said Prof Winkler, noting that Oxford University researchers are currently conducting a double blind, randomised, controlled trial at three locations and planned to include 1,000 subjects. The study is funded by the Wellcome Foundation and supported by the UK Department of Justice and the Prison Service.
“In my view, this could be milestone research, the research that finally makes the world take seriously the connection between diet and mental ill health, in all its forms,” said Prof Winkler.
No challenge to the methods of the new Oxford study has come forward, noted Prof Winkler. “If the results turn out similar to the Gesch and Dutch studies, then it could be a significant breakthrough,” he said.
Professor Crawford added that the link between diet and aggressive behaviour “makes sense on the basis of evidence of links between major depression, suicide and homicide reported by Dr Joseph Hibbeln at the National Institutes of Health in the USA and of course our stuff demonstrating the absolute dependence of the brain on the long chain essential fatty acids.”
Source: Aggressive Behavior
March/April 2010, Volume 36, Issue 2, Pages 117-126
“Effects of nutritional supplements on aggression, rule-breaking, and psychopathology among young adult prisoners”
Authors: A. Zaalberg, H. Nijman, E. Bulten, L. Stroosma, C. van der Staak