February 3rd, 2011
06:30 PM ET
It's still a mystery, and parents and scientists alike are looking for answers about why some 5 million children in the United States have attention deficit hyperactivity disorder, a condition marked by impulsive behavior and a lack of focus. There have been genetic links shown, and plenty of accusations of misdiagnosis, but now the attention turns to a different explanation: Diet.
A team of scientists from the Netherlands set out to demonstrate in a study, published in the Lancet, that there could be a connection between what children eat and their ADHD-like behaviors. They go as far as to say that the standard of care for ADHD should include a restricted diet.
But the researchers did not pinpoint any specific foods that appear to induce ADHD symptoms, and their ideas must be explored further in other studies before being considered definitive, experts say.
"At this time it is very difficult to tell parents which foods to avoid," said Dr. Jaswinder Kaur Ghurman of the department of Child and Adolescent Psychiatry at the University of Arizona in Tucson, who was not involved in the study. It may vary by child, she said.
The diet experiments described in the paper focus on about 100 children with a diagnosis of ADHD aged 4 to 8. They were not selected for any food sensitivities. One group of these children spent five weeks on an "elimination diet." This began with a "oligoantigenic" diet - meaning, foods least likely to cause an allergic reaction - including meat, vegetables, pears, and water, as well as additional foods such as potatoes, fruits, wheat. For children whose behavior did not respond to that diet, foods were further limited to just a few.
Researchers found that 64% of children who participated in this diet group showed significant improvement in their ADHD symptoms, as observed by parents and teachers.
On this basis, they suggest that this elimination diet method could be a useful tool to see which foods might be causing a problem for the child.
But that means that 36% did not have a positive response to the diet or weren't compliant with it, not including the 16 other children who didn't want to participate at all. This raises larger issues about whether parents and children would actually comply with this treatment, says Dr. Andrew Adesman, chief of Developmental & Behavioral Pediatrics at the Steven and Alexandra Cohen Children's Medical Center of New York in New Hyde Park, New York.
The researchers also did a blood test experiment measuring immune response, and concluded that it was not helpful in predicting which foods might be triggering ADHD symptoms.
Adesman criticized the study's design, noting that it lacked truly independent observers. Parents and teachers knew what the children were eating, and the pediatricians likely knew as well. Also, most children in the study were boys. Additionally, the results may not be applicable to children who do not have hyperactivity, but nonetheless exhibit the attention deficit problems of ADD. There is also no measure of safety or effectiveness for more than several weeks.
The issue of foods in ADHD is still controversial generally. Some research such as this has suggested diet as a cause, but there is no proof. Ghurman says it's possible that a child may already have some vulnerability, which particular foods may trigger. But more study must be done to further evaluate this theory.
Ghurman and Adesman agree that parents of children with ADHD should be aware of this research but that they should not attempt to try a restricted elimination diet alone. If you are interested in this line of ADHD treatment, talk to a pediatrician and only carry out such an intervention under his or her supervision.
About this blog
Get a behind-the-scenes look at the latest stories from CNN Chief Medical Correspondent, Dr. Sanjay Gupta, Senior Medical Correspondent Elizabeth Cohen and the CNN Medical Unit producers. They'll share news and views on health and medical trends - info that will help you take better care of yourself and the people you love.