Diets high in processed foods are causing bad behavior and learning difficulties in children, scientists in the U.K. warned.

They said “junk” food prevents the brain from working properly, leading to underachievement and a host of disorders. Such foods not only lack the vitamins, minerals and essential fatty acids that boost brain power but actually reduce the body's uptake of nutrients that improve concentration, the study found.

Thousands of children given medication to combat attention deficit disorder might be better off simply improving their diet, according to the research.

The Oxford University study showed that giving children essential fats found in fish and nuts could improve their brain power.

Their ability to learn was increased and their behavior dramatically improved by supplementing their diets with such fats.

Startling results in children who were underachieving and in some cases being disruptive were recorded after just three months.

The study involved more than 100 British children battling with physical coordination problems.

They were given daily supplements rich in omega-3 essential fats that are vital for brain development but have been reduced in the typical diet over the last couple of decades.

In the study, around 40% of children given omega-3 supplements made dramatic improvements in reading and spelling.

There was also a significant improvement in concentration and behavior, according to a report in this month's issue of the American journal Pediatrics.

Researchers were led by Dr. Alexandra Richardson, from Oxford University's department of physiology.

“What we've shown is that you can improve behavior and learning with these oils,” she said.

“Food affects behavior. To ignore the role of nutrition is indefensible. If you paid attention to diet, you could really make a difference.”

Patrick Holford, who runs the Brain Bio Centre which tackles mental health problems through nutrition, said, 'We're seeing outrageous imbalances in brain chemistry caused by the kinds of foods that sadly millions of kids are eating, and no one's doing anything about it.

“These kids are digging their own graves with a knife and fork. We know some fats found in processed and fried foods should be avoided.

“However, there are other fats that are essential, and a deficiency can negatively impact a child's behavior.”

The study involved 117 children aged five to 12 in schools in County Durham.

The children were of normal ability but underachieving and suspected of having dyspraxia, a condition that affects coordination. It is thought to affect at least 5% of British pupils.

Even greater numbers have learning and behavioral disorders, such as dyslexia and attention deficit hypercomparedactivity disorder. Half the children were given omega-3 essential fats capsules for three months, while the remainder were given “dummy” treatment with capsules of olive oil.

Those on omega-3s made up to 10 months' progress in reading in three months, with those taking olive oil who made normal progress.

When the children swapped treatments, there was a similar jump forward for those transferred to omega-3s for the second three-month period.

After three months on the supplements, half showed such improvement they were no longer classified as having problems.

In some cases, children improved their reading age by up to four years.

Richardson, who is also co-director of the Food and Behaviour Research charity, said unhealthy dietary fats can actually displace the healthy fats in the brain.

Known as trans fats, they are mostly found in processed foods such as chips, cookies and cakes. Many teenagers get 40% of their calories from fat. The researchers are worried that such poor diets could permanently damage brain development.