Kids with attention deficit hyperactivity disorder, or ADHD, are normally treated with behavioral therapy and stimulant medications. A new study suggests that a highly restricted diet can be just as effective at reducing symptoms in a majority of children with ADHD.
Diet is not a routine consideration in diagnosing and treating ADHD in the U.S. or in Europe, where the study was done. Many doctors are open to the idea that certain foods might trigger ADHD symptoms in some kids, though they believe it's a relatively minor factor in most cases.
"There's no question that foods have effects on people's mood, sleep and energy," says Dr. David Schab, a psychiatrist at Columbia University in New York. However, he adds, the current state of knowledge about what foods are problematic and which kids are susceptible is still too limited to be of much use for doctors or their patients.
The Centers for Disease Control and Prevention estimates that 9.5% of school-age children in the U.S. have ADHD. That adds up to more than 5 million kids who could potentially benefit from a symptom-reducing diet.
Here's a closer look at how dietary changes may — or may not — help kids with ADHD.
Children with attention deficit hyperactivity disorder exhibit a range of symptoms. Many have trouble staying focused on a single task and become bored or distracted quite easily. Others are unable to sit still, stay quiet or be patient. Some kids have a combination of these symptoms, plus others, according to the National Institute of Mental Health.
In the study, published last month in the Lancet, 100 children with ADHD symptoms who were 4 to 8 years old were divided into two groups. Half were allowed to eat only a small number of foods for five weeks; their diets were customized from a short list of ingredients that included water, rice, turkey, lamb, lettuce, carrots, pears and other hypoallergenic foods. The rest of the kids were counseled (along with their parents) about healthful eating but allowed to eat whatever they wanted.
At the end of the study, 64% of the kids on the limited diet showed significant improvement on a variety of standard rating scales. Though the initial scores for all of the kids in this group put their ADHD symptoms in the moderate-to-severe range, after the diet intervention their symptoms were classified as either mild or nonclinical.
"It's shocking to most people," says psychologist Lidy Pelsser of the ADHD Research Center in Eindhoven, the Netherlands. "The parents were shocked. The children said they felt so different, as if some mad thing in their head wasn't there anymore."
Previous studies have found similar effects, but, like this one, they all had fundamental problems that made it easy for doctors to dismiss them.
For example, it's impossible to implement such a radical diet without kids and their parents realizing they're in the treatment group. That can affect the results because parents who know their child is receiving treatment may look harder for improvements. Their heightened expectations, in turn, may affect their kids' behavior. Children with the disorder often improve with regular, focused attention.
"These are not easy things to tease out," says Dr. Jaswinder Ghuman, a child psychiatrist at the University of Arizona in Tucson who treats ADHD.
Some experts question whether all the children in the Lancet study actually had ADHD. Making a diagnosis in 4- and 5-year-olds is tricky, since the ability to sustain focused attention doesn't usually show up until age 6 or 7, says Robert Myers, a psychologist at UC Irvine who has worked with ADHD patients for 30 years.
One way the new study differed from the preceding ones is that it didn't select only kids who had an allergy-related condition, such as asthma or eczema, but rather enrolled anyone with an ADHD diagnosis. That suggests food triggers may be important in a broader population of patients than previously thought. Until now, the consensus has been that food sensitivities play a role in only a small subset of ADHD cases.
Whether the Lancet study will change many doctors' minds remains to be seen. In a commentary that accompanied the Lancet study, Ghuman wrote that, while the diet's benefits were impressive, following it for more than five weeks could have detrimental health consequences.
Pelsser is the first to admit that no one can follow such a severe diet for very long. The children in her study have been gradually adding foods back to their diet. "We've followed all these children for about a year, and each child reacts to different foods," she says. For one child, triggers included beets, tomatoes, wheat and bananas; for another, it was fish, pork, eggs and oranges.
The idea of treating ADHD through diet modification goes back to at least the 1970s, when researchers began experimenting with a regimen called the Feingold diet that eliminated food additives and foods containing natural salicylates, such as apples, strawberries, almonds and tomatoes. Though the diet achieved only modest results, it is still used in some circles, Myers says.
Other researchers have charged that food additives — such as artificial colors, flavors and preservatives — are likely triggers for hyperactive behavior. A 2007 Lancet study of 297 children who did not have ADHD found that drinks laced with artificial colors and the preservative sodium benzoate increased activity to levels that were between one-half and two-thirds as high as seen in kids with ADHD who are not on medication. "Relatively modest amounts of food additives caused hyperactive symptoms in kids," says Schab, the Columbia psychiatrist.
To be sure, the prospect of treating ADHD with diet instead of drugs would appeal to many parents, Ghuman says. But parents who want to give it a try should be sure to consult their child's physician first, she warned: "It's not that simple to do appropriately."