A growing body of research suggests that poor nutrition may be having a detrimental impact on all areas of children's development.
The latest studies are focusing on the role diet has to play in nurturing healthy, mentally and socially adept children.
A study released earlier this month by Britain's Oxford University, found that children whose diets are full of the wrong fats may be suffering educationally and physically.
More than 100 children were involved in the study, all of whom had been suffering physical co-ordination difficulties and were underachieving at school.
They were given daily supplements of omega-3 oils, which contribute to brain development but are getting harder to find in modern diets.
By the end of the study about 40pc of the participants had made dramatic improvements in reading and spelling, making up to 10 months progress in the three-month trial period.
Children in the control group, who did not receive the omega-3 oils, made only normal progress.
There was also a considerable improvement in concentration and behaviour in those taking the oils.
Half showed such improvement that they were no longer classified as having problems and some children even improved their reading age by up to four years.
"What we've shown is that you can improve behaviour and learning with these oils," said lead researcher and Food and Behaviour Research charity director Dr Alexandra Richardson.
"Food affects behaviour.
"To ignore the role of nutrition is indefensible."
Further research carried out by Dr Richardson suggests that the fats in junk food actually stop the brain working properly, leading to under-achievement at school and a lack of concentration.
She believes that this is the result not just of the poor nutrition junk food offers, but also because it can reduce the body's absorption of nutrients from other sources which can improve concentration.
The trans fats found in many highly-processed foods are thought to displace healthy fats in the brain.
"Every time children eat crisps, biscuits or cakes they are filling themselves with what are essentially toxic fats," noted Dr Richardson.
"There are no health benefits and many health costs to these hydrogenated fats, yet they are all that some children and adults are eating.
"They are replacing the essential fats that would make their brain and body work properly with ones that are clogging up the machinery."
Poor diet can have long-lasting effects, say researchers at the University of Southern California, US, who found a lack of zinc, iron, vitamin B and protein in the first three years of life caused bad behaviour in later years.
They followed the development of more than 1,000 children in Mauritius over 14 years.
At eight the children who had been given poor diets in infancy were more likely to be irritable and pick fights than those who had enjoyed healthy food.
At 11 they were more likely to swear, cheat and get into fights, while by 17 they were more likely to steal, bully and take drugs.
"Poor nutrition leads to low-IQ, which leads to later anti-social behaviour," said report co-author Adrian Raine.
Of course there are other factors involved in such behaviour, and some scientists criticised the study saying that the children who had been malnourished may have suffered from other deprivations, making them anti-social.
However, small scale studies suggest that there is more to this issue and are inspiring scientists to do more research.
In one such study five-year-old British twins Christopher and Michael Parker, who had the same environment and upbringing, were put on different diets for a fortnight.
All food additives were removed from Michael's diet and by the end of the fortnight his IQ had improved by 25 per cent, compared to Christopher's improvement of just 10pc.
Before the experiment they had each made the same mistakes on the tests and completed them in exactly the same time.
Their mother also told researchers that Michael had become much calmer than his brother.
Parents in a Southampton University, UK, study surprised researchers by informing them that their children were noticeably better behaved while on additive-free diets, regardless of whether they had any diagnosable condition beforehand.
The study involved normal, hyperactive and allergic children and all were found to have benefited from the removal of artificial colourings and preservatives from their food.
A larger-scale, long-term study, involving 900 children, is now underway to explore the issue further.
"We are trying to get some hard evidence," said Professor John Warner.
"I want this to address a fundamental issue, which is why do we have coloured food?
"Why can't people have pale salmon rather than pink salmon?
"It's absolutely imperative to have follow-up studies because we are not now just talking about a population of children with a particular problem.
"We are saying there's a potential for this to be an effect on all children.
"And if that really is the case, then food colouring should be removed."