Bernard Gesch, a senior scientist at Oxford University, told CYP Now that despite studies providing evidence of a link between the effect of certain foods and supplements on the brain, changes to the current system have not been made.
His criticism comes as it emerged last week that only one young offender institution (YOI) employs a nutritionist. Answering a Parliamentary question, justice minister Maria Eagle revealed a nutritionist is only employed at Huntercombe YOI in Henley-on-Thames.
A separate response by Eagle laid bare the difference in weekly spend per head on food across YOIs. The average weekly food cost at Feltham YOI and Werrington YOI came to £22.48 - some £360-a-year more than the lowest spenders on food, Downview YOI in Surrey at £15.54 a week.
Gesch, who is also director of research charity Natural Justice, argues that a daily per head spend of, in some cases, little more than £2 is not enough to provide young offenders with all the nutrients they need.
Natural Justice is running a trial at three YOIs - Hindley in Wigan, Lancaster Farms in Lancaster, and Polmont in Falkirk - to see if nutritional supplements can improve behaviour.
A smaller pilot study at Aylesbury YOI in 2002 showed that inmates receiving supplements committed a third fewer offences.
Gesch said: "The pressure is downwards in terms of commitment and spending. This is despite evidence suggesting very clearly that diet is maybe one of the most important factors in terms of maintaining behavioural health of the prisoners.
"It is not a criticism of the catering managers who work extremely hard to try and get the best food on the table within the budgets they have been given. The problem is more at a policy level."
A Prison Service spokesperson said: "There is no requirement for YOIs to directly employ a nutritionist but nutritionists visit YOIs to help make improvements to menus and keep institutions up to date on research findings. The National Offender Management Service continues to work with the Department of Health, the Food Standards Agency and others to encourage prisoners to eat more healthily."
