Anyone witnessing a child's manic meltdown after a birthday party is likely to understand why many parents believe that certain foods affect kids' behavior. So it is not surprising that some parents believe that diet is behind children's attention-deficit hyperactivity disorder (ADHD) — particularly sugary beverages, candy, food colorings, and added preservatives.

But pediatricians and dietitians alike have been long been skeptical of a real, causal connection between diet and ADHD in children.

The restrictive diet reduced the symptoms of ADHD in 64 percent of the children. Those on the control diet showed no improvement in symptoms.

According to the National Institute of Mental Health, ADHD is one of the most common childhood disorders. It usually becomes evident in the preschool or early elementary years with the median age of onset being seven years of age. Children with ADHD have trouble paying attention, focusing, and controlling their behavior, and they exhibit hyperactive behavior.

A recently published Dutch study suggests that food allergies may be the cause of ADHD. Previous studies had considered whether sugar or food coloring caused the behavioral problems of ADHD. This study, led by Dr. Jan Buitelaar, looked at the idea that food may cause an allergic or other hyperactivity-stimulating reaction in the brain.

One hundred children between the ages of 4 and 8, mostly boys, who were diagnosed with ADHD were recruited for the study. Half were put on a restrictive elimination diet that consisted mainly of rice, white meat, such as turkey, and the few fruits and vegetables that generally do not cause allergies. Foods such as wheat, tomatoes, oranges, eggs, and dairy products were eliminated because they are often associated with food allergies or intolerances. The other 50 children served as a control group and received instruction on a healthy diet.

During the first phase of the study, researchers observed the behavior of the children for a period of five weeks. They found that the restrictive diet reduced the symptoms of ADHD in 64 percent of the children. Those on the control diet showed no improvement in symptoms. After five weeks, thirty children who showed improvement in their symptoms on the restrictive diet had other foods gradually added to their diet to see if their symptoms worsened. Nineteen children had a relapse in symptoms.

Given the findings, the researchers suggested that this diet may improve the behavior of children with ADHD and help them get off their medications. Dr. Buitelaar recommended that the restrictive elimination diet become part of the standard of care for children diagnosed with ADHD.

But not all children benefit from diet restriction and for this, and other reasons, the standard way to treat children with ADHD is to take all aspects of their lives – family, culture, school, friends, and other influences – into consideration.

Parents of ADHD children often seek help from alternative therapies, including special diets. Eliminating candy or adding bananas is such simple advice that many parents will eagerly try any kind of dietary manipulation; however, restrictive diets put a child at risk for nutritional deficiencies and impaired growth and development. Any type of restrictive diet for children should be carried out under the supervision of a physician and a dietitian.

Diet does appear to affect the ability of children to pay attention and focus in school. Nutritional problems can manifest themselves as behavior and learning problems in children. In particular, a lack of iron adversely affects behavior, mood, attention span, and learning ability in children. Missing a meal, such as breakfast, can also impair a child’s ability to pay attention and perform well in school.

The study was published in the February 5, 2011 issue of The Lancet.