Summary of evidence: nutrition for the brain

Why Diet Affects Behaviour

Humans are not very large, not very strong, not very fast; yet we dominate the globe – because our sociability enables us to communicate and cooperate highly effectively. Evolutionary pressure favouring cooperation was probably why our brains contain more neurones and interconnections than any other animal on the planet. Despite weighing only 2% of our body weight, they consume 25% of all the body's energy. They need not only sugar, fats, oxygen and proteins for energy and maintenance, but also, crucially, vitamins, and minerals, and essential fatty acids. The latter nutrients, such as omega-3s, are essential for brain health, but must come from the diet, as humans cannot synthesise them. Historically we gained them through eating fish and seafood, fresh fruit and vegetables, wholegrains, nuts and seeds. 

However, the latter half of the 20th century and since has seen a serious decline in consumption of all these staples in favour of processed foods that contain little of the important nutrients required for physical and mental health. Poor diet is now a leading risk factor for non- communicable illnesses like diabetes, stroke, heart disease and mental ill health; costs of the last of these – mental health - were estimated by Dr Joe Nurse and others to exceed those for heart disease and cancer combined.

An alarming rise in the levels of crime has occurred over precisely the same period. Higher levels of mental ill health are also seen in prisoners in jail than in the general population. They are also disproportionately likely to have had disadvantaged backgrounds and therefore to be nutritionally deprived. Although there are multiple reasons for mental illness and for criminal behaviour, there is powerful evidence that lack of essential nutrients for the brain has played a critical role.

In the ALSPAC* study of child development, the lower the mothers’ seafood consumption during pregnancy, the lower were their children’s verbal intelligence and pro-social behaviour eight years later. These findings contributed to the conclusion of the All Party Parliamentary Food and Health Forum (2008) that there is now sufficient evidence of links between diet, mental health and antisocial behaviour to recommend both further government-funded research and policy changes.

Randomised Control Trials (RCTs) are the ‘gold standard’ for demonstrating causation – in this case showing that improving micronutrient intake can cause a reduction in antisocial behaviour, since all other factors are the same in those receiving extra nutrients compared with the controls. We detail below five such trials carried out in prisons (and a further study in troubled school), all of which have confirmed a beneficial effect on prisoners’ behaviour of adding nutrient supplements to their diets. There have been no studies, to our knowledge, that have failed to find such an effect.

* The Avon Longitudinal Study of Parents and Children (ALSPAC), University of Bristol, has studied the effects of diet and many, many, other variables on the development of 15,247 children born in 1991/92 and followed up every three years thereafter.

Conclusion

Violence in prisons is rising dramatically for many reasons but the evidence from these RCTs shows that it can be mitigated by providing the nutrients required for improved cognition, emotional regulation and sociability; this will benefit not only the prisoners themselves but also prison staff  who are currently under enormous pressure. Supplementation is a faster way to normalise nutrient status than changes in diet, and is particularly appropriate for pregnant women and arguably during the first few weeks of a sentence. But implementing techniques that persuade people to improve their diets – and importantly, providing access to appropriate menus in closed conditions - will be the more effective way to improve mental health, well-being and behaviour both inside and outside prison.

Notable studies

> Schoenthaler et al., 1997 was the first to show in an RCT that supplementing young offenders’ diets with vitamins and minerals (not omega-3s) could reduce their antisocial and violent behaviour significantly. However this was only a small study (n=40), choosing only those who committed offences at baseline.

> Gesch, Hammond, Hampson, Eves, & Crowder, 2002 conducted an RCT at YOI Aylesbury  (n = 275 offenders). Supplementation with omega-3 and omega-6 fats, vitamins, and minerals resulted in a 34% reduction in all offences in the supplemented group. Violent offences dropped by 37%.

> Zaalberg, Nijman, Bulten, Stroosma, & van der Staak, 2010 repeated the Aylesbury study in 221 prisoners in a Dutch prison, and again found that reported incidents were fewer in the supplemented group.

> A supplementation RCT by Tammam, Steinsaltz, Bester, Semb-Andenaes, & Stein, 2015 gave omega-3s, vitamins, and minerals to 196 14-15 year olds from Robert Clack School, Dagenham (in the UK's fourth most deprived borough). Although the supplements were not popular (real foods would have been preferred), pupils’ behaviour significantly improved.

> In an RCT of 145 young offenders, Raine, Leung, Singh, & Kaur, 2020 administered only omega-3 supplements for 3 months, and found reductions in both officer reports and self-reported Impulsive-Aggression scores (which fell by 34%), changes that were maintained for the next 6 months.

> A supplementation RCT with omega-3 and vitamins and minerals in three UK YOIs  (n = 835, in preparation). Despite problems with data collection owing to external circumstances, found a 12-18% reduction in violent offences.

References

> Azevedo, F. A. C. et al., 'Equal numbers of neuronal and nonneuronal cells make the human brain an isometrically scaled-up primate brain', Journal of Comparative Neurology, 513 (2009).

> Nature Medicine Editorial, 'Untangle food industry influences on health', Nature Medicine, 25 (2019); Afshin, A. et al., 'Effectiveness of dietary policies to reduce noncommunicable diseases', in Cardiovascular, Respiratory, and Related Disorders, ed. by D. Prabhakaran, et al. (Washington (DC): The International Bank for Reconstruction and Development/The World Bank, 2017); Micha, R. et al., 'Association between dietary factors and mortality from heart disease, stroke, and type 2 diabetes in the United States', JAMA, 317 (2017).

> Rehm, C. D. et al., 'Dietary intake among US adults, 1999-2012', JAMA, 315 (2016); Wrieden, W. L. et al., 'Slow pace of dietary change in Scotland: 2001-9', British Journal of Nutrition, 109 (2013).

> Afshin, A. et al., 'Health effects of dietary risks in 195 countries, 1990-2017: a systematic analysis for the Global Burden of Disease Study 2017', Lancet, 393 (2019); Simopoulos, A. P., 'Omega-3 fatty acids in health and disease and in growth and development', American Journal of Clinical Nutrition, 54 (1991).

> Thompson, G. et al., 'Recorded crime', in Olympic Britain - Social and Economic Change since the 1908 and 1948 London Games, (House of Commons Library, 2012), p. 163.

> Simister, J., 'Are doctors getting the balance right? Treatment for depression in England, 1983 to 2017', Women's Health, 8 (2019).

> Public Health England, Statistical commentary: Children living with parents in emotional distress, 2019 update (https://www.gov.uk/government/publications/children-living-with-parents-in-emotional-distress-2019-update/statistical-commentary-children-living-with-parents-in-emotional-distress-2019-update).

> Duque, M. and McKnight, A., 'Understanding the relationship between inequalities and poverty: mechanisms associated with crime, the legal system and punitive sanctions' (STICERD: London School of Economics, 2019, http://sticerd.lse.ac.uk/dps/case/cp/casepaper215.pdf).

> Adan, R. A. H. et al., 'Nutritional psychiatry: towards improving mental health by what you eat', European Neuropsychopharmacology, 29 (2019); Perica, M. M. and Delas, I., 'Essential fatty acids and psychiatric disorders', Nutrition in Clinical Practice, 26 (2011).

> Cadenhead, K. S. et al., 'Metabolic abnormalities and low dietary omega 3 are associated with symptom severity and worse functioning prior to the onset of psychosis: findings from the North American Prodrome Longitudinal Studies Consortium', Schizophrenia Research, 204 (2019).

> Hibbeln, J. R. et al., 'Maternal seafood consumption in pregnancy and neurodevelopmental outcomes in childhood (ALSPAC Study): an observational cohort study', Lancet, 369 (2007).

> The Associate Parliamentary Food and Health Forum report is available online at http://www.fhf.org.uk/meetings/inquiry2007/FHF_inquiry_report_diet_and_behaviour.pdf.

> Benton, D., 'The impact of diet on anti-social, violent and criminal behaviour', Neuroscience and Biobehavioral Reviews, 31 (2007); Choy, O. and Raine, A., 'Omega-3 supplementation as a dietary intervention to reduce aggressive and antisocial behavior', Current Psychiatry Reports, 20 (2018).

> Schoenthaler, S. et al., 'The effect of randomized vitamin-mineral supplementation on violent and non-violent antisocial behavior among incarcerated juveniles', Journal of Nutritional and Environmental Medicine, 7 (1997).

> Gesch, C. B. et al., 'Influence of supplementary vitamins, minerals and essential fatty acids on the antisocial behaviour of young adult prisoners. randomised, placebo-controlled trial', British Journal of Psychiatry, 181 (2002).

> Zaalberg, A. et al., 'Effects of nutritional supplements on aggression, rule-breaking, and psychopathology among young adult prisoners', Aggressive Behavior, 36 (2010)..

> Hansen, A. L. et al., 'A long-term fatty fish intervention improved executive function in inpatients with antisocial traits and a history of alcohol and drug abuse', Scandinavian Journal of Psychology, 56 (2015).

> Tammam, J. D. et al., 'A randomised double-blind placebo-controlled trial investigating the behavioural effects of vitamin, mineral and n-3 fatty acid supplementation in typically developing adolescent schoolchildren', British Journal of Nutrition, 115 (2016).

> Raine, A. et al., 'Omega-3 supplementation in young offenders: a randomized, stratified, double-blind, placebo-controlled, parallel-group trial', Journal of Experimental Criminology, (2020).