3 Prisons Study: Reducing serious incidents among offenders through nutrition

Publication date

24 September 2009


Professor John Stein (Principal Investigator)
Dr Bernard Gesch (Co-ordinator)
Dr J. Tammam (Team leader)
Ms C. Galloway


This study was funded by a grant from the Wellcome Trust and was carried out by the Department of Physiology, Anatomy and Genetics (DPAG) at the University of Oxford.


  • The study investigated the effects of nutrient supplements on prisoners’ offending behaviour

  • The supplements contained vitamins, minerals and omega-3 fatty acids

  • Results showed that supplementation reduced offending behaviour in the prisoners 

The study

The study was carried out in three Young Offender Institutions - Hindley, Lancaster Farms and Polmont. The teams recruited 856 prisoners to join a study of the effect of nutritional supplements on offending behaviour.  Of this number, 771 reached the 80% compliance required to be included in the analysis.

What we did

We recorded prisoners’ disciplinary incidents, and assessed their nutrient status from blood samples.

Participants were then randomly assigned to take daily capsules containing vitamins, minerals and omega-3 fatty acids or placebo, with neither the researchers or prisoners knowing who had got which. 

After four months, we took blood samples again, compared the disciplinary records of those on active versus placebo capsules and related these to changes in their nutrient blood levels.

Key findings

In the prisoners who received the active capsules, their blood levels of omega 3s, vitamins and minerals increased, whereas the placebos’ did not. 

In the group of prisoners receiving the supplements serious offences decreased by 17% and all offences decreased by 12%, whereas in those receiving the placebo their offence rates remained unchanged. 

Results confirmed that nutritional supplementation can reduce offending in prisons.