THE drive to improve the nation's diet has targeted schools, workplaces and hospitals - now menus in Scottish prisons are to be overhauled to encourage healthy eating.

Porridge may once have been standard food for those doing time, but modern menus featuring chips and stodgy fare have led to criticism of the Scottish Prison Service (SPS) for failing to provide inmates with enough nutrients.

Nutrition standards have now been drawn up in conjunction with the Food Standards Agency, which will be piloted in three locations. If successful, it is anticipated that the scheme will be rolled out to around 7000 prisoners in 16 institutions across Scotland.

The move comes at a time when there is an increasing focus on the role of nutrition in preventing anti-social behaviour. One leading researcher, who is carrying out a global research project for the World Health Organisation, told the Sunday Herald that early results suggest poor diet could be a factor in nearly 40% of violent behaviour.

The nutrient standards will be trialled at Greenock, Shotts and Cornton Vale, Scotland's only women's prison, from now until March next year. During this time, the food budget for each prisoner will rise from £11.57 to £13.50 per week.

The guidelines set out how much nutrient and energy the average male and female requires and gives examples of portion sizes of fruit and vegetables. However, it states that as each prison has different catering facilities, it is not possible to draw up a standard menu.

A spokesman for the SPS said: "Nutritional guidelines were developed to ensure that we were meeting the requirements to provide prisoners with a healthy balanced diet and to keep abreast of developments within the external catering community.

"The hoped-for outcomes are to improve prisoners' diet - get more people eating their five portions of fruit and veg - improve standard of catering in terms of nutritional content and temperature at serving and improve prisoners' perception and ratings of food."

Two years ago in his annual report, Scotland's jails watchdog Dr Andrew McLellan criticised the quality and standard of food given to inmates, pointing out that prisoners were only able to eat an average of less than three portions of fruit and vegetables a day."It is possible that encouraging prisoners to eat nutritious food might be a contribution not only to healthier living, but also to less destructive behaviour," he said.

While the SPS says that the new guidelines are not being introduced with a view to improving prisoners' behaviour, research has suggested that sugary junk-food diets could be a factor in offending. Next year a major study is due to take place at Polmont Young Offenders Institute, near Falkirk, to investigate how diet can change behaviour.

Study leader Bernard Gesch, director of the charity Natural Justice, which researches the causes of criminal behaviour, said there was an "urgent need" to reappraise modern diets in terms of the impact on the brain. One study previously carried out by Gesch at a young offenders institute in England found improving the diets of inmates cut offences by 25%.

"Improving prisoners' diets will improve their health and obviously should be warmly welcomed," he said.

"There is also an emerging body of evidence to suggest that it can do far more. Quite possibly, some of the people that are currently in prison need never have been there in the first place if they had been properly nourished."

Gesch, a senior research scientist at Oxford University, said that a study was also under way, in conjunction with the World Health Organisation, to find out how much poor diets are contributing to aggressive behaviour on a global scale.

"Our preliminary estimates suggest that as much as 37% could be a reasonable starting point for estimating how much violence could be attributable to poor modern dietary practices," he said.

"If these figures turn out to be anything like correct, then we may have identified one of the most important single factors in modifying, in a positive sense, social behaviour."

John Scott, chairman of the Howard League for Penal Reform in Scotland, welcomed the new guidelines as having the potential to improve the rehabilitation of prisoners. "Hopefully this will have results and spread through the prison service," he added.