LONDON Children with attention-deficit hyperactivity disorder (ADHD) should be fed a special diet to help their carers determine whether certain foods are making their condition worse, Dutch scientists said on Friday.
In a study of 100 children with ADHD -- one of the world's most common child mental disorders -- scientists from Radboud University and the ADHD Research Center in the Netherlands found that a restricted diet led to significant improvements in the symptoms of some ADHD sufferers.
"Dietary intervention should be considered in all children with ADHD, provided parents are willing to follow a diagnostic restricted elimination diet for a five-week period, and provided expert supervision is available," the scientists said in their study in The Lancet medical journal.
ADHD is estimated to affect around 3 to 5 percent of children worldwide. Children with ADHD are excessively restless, impulsive and distracted, and often have difficulties at home and in school. There is no cure, but the symptoms can be kept in check by a combination of drugs and behavioral therapy.
Previous studies have suggested that in some children, ADHD might be an allergic or hypersensitivity disorder that could be triggered by any type of food that can cause allergic reactions.
In this study, children aged four to eight years diagnosed with ADHD were divided into two groups and given either an elimination diet or a general healthy diet for five weeks.
Jan Buitelaar of Radboud University, who led the study, said in a telephone interview that the elimination diet was restricted to rice, water, white meat such as turkey, and some fruits and vegetables that are generally considered as unlikely to cause allergies.
Foods such as wheat, tomatoes, oranges, eggs and dairy products were kept out of the diet as they are often linked with allergies or food intolerances.
After five weeks, children who reacted well to the restricted diet went into a second phase in which different groups of foods were gradually added to their diet and their symptoms monitored to see if they worsened. The foods were different for each child, based on blood results.
In the first phase, 64 percent of children in the diet group had significant improvements in their ADHD symptoms, Buitelaar said, and showed a decrease in "oppositional defiant disorder symptoms" such as challenging behavior.
External experts commenting on the research said it offered "excellent evidence" that dietary changes might be very beneficial for some children with ADHD, but they questioned whether it would be cost-effective in time and resources.
"We need to know more about how expensive the intervention is, how motivated parents need to be to make it work, and how easy it is for parents to get their ADHD child to stick to the diet," said David Daley, professor of psychological intervention and behavior change at Britain's Nottingham University.
Professor Jim Stevenson of Southampton University said it was good for parents to explore alternative treatment options.
"Many parents are reluctant to use a drug treatment and it is important that alternatives such as the few foods approach can be shown to be effective," he said.
(Editing by Paul Casciato)