MONDAY, Jan. 9 (HealthDay News) -- There's limited evidence that any particular diet or supplement helps kids with attention-deficit/hyperactivity disorder (ADHD), but at least some research suggests that omega-3 fatty acids may help while fatty "Western-style" diets do these children no favors.

Researchers from Children's Memorial Hospital in Chicago reviewed previous studies on diets and supplements that have been tried in children with ADHD. Among the diets tested: restricting sugar, which some parents believe worsens hyperactivity; avoiding food containing additives and preservatives, known as the "Feingold diet"; an "elimination diet" that avoids foods most often implicated in food allergies; and supplementing with omega-3 fatty acids, such as fish oil capsules.

Little research supports the idea that sugar or artificial sweeteners affect children's behavior, according to the review. Nor is there much evidence from controlled trials to support the Feingold diet, which first became popular in the 1970s and advocates avoiding food that contains red and orange dyes and preservatives (including apples, grapes and lunch meats).

Yet, some studies have suggested some kids with ADHD benefit from an elimination, also known as a hypoallergenic, diet. But that typically means forgoing cow's milk, cheese, wheat cereal, eggs, chocolate, nuts and citrus foods, which can be tough on the child and on the family, said study author Dr. J. Gordon Millichap, a professor emeritus at Northwestern University Medical School and neurologist at Children's Memorial Hospital in Chicago.

Moreover, the results of studies on hypoallergenic diets have been mixed. "We find the hypoallergenic diet might be effective, but difficult for families to manage them," Millichap said.

One study by Australian researchers suggested that kids who ate a typical "Western-style" diet that's high in fat, salt and refined sugars had a higher risk of ADHD than kids who had a healthier diet that was rich in fish, vegetables, fruit and whole grains and that contained lots of fiber, folate and omega-3 fatty acids.

Dr. Roberto Lopez-Alberola, an associate professor and chief of pediatric neurology at University of Miami School of Medicine, said he strongly advocates children with ADHD following such a healthier diet and avoiding dyes, preservatives and other additives.

Though the precise biological mechanism hasn't yet been uncovered, Lopez-Alberola believes the increase in obesity rates and in ADHD are not unrelated, and unhealthy modern diets may be contributing to the problem.

"I am a firm believer that we ultimately are what we eat, and unfortunately as a result of our poor Western diet, we see this in the increase in the rate of obesity, particularly in the young population," Lopez-Alberola said. "The fast foods. The processed food. The preservative-rich foods . . . In the same way we see an impact physically, it's going to have an impact from the neurodevelopmental standpoint. It's not surprising we see a parallel in the increase in obesity and in ADHD."

Another study, conducted by researchers in England in children who were excessively clumsy -- some of whom also had ADHD -- found that omega-3 supplements didn't help with motor skills, but did seem to help with attention.

Other research has found that many kids with ADHD had unusually low levels of iron in the blood. One Israeli study found that the parents of kids given iron supplements reported less ADHD symptoms in their kids, but teachers saw no such effect.

Therein lies much of the problem with research that looks at dietary interventions for ADHD, said Dr. Andrew Adesman, chief of developmental and behavioral pediatrics at Steven & Alexandra Cohen Children's Medical Center of New York.

The placebo effect can be powerful. Much of the research on dietary interventions compares dietary interventions to no treatment, while there's little research that compares a diet to stimulant medications such as Ritalin (methylphenidate) or Adderall (dextroamphetamine and amphetamine), which have decades of research showing that they're effective in kids with ADHD, Adesman said.

"For better or worse, medications are the single most effective treatment available for ADHD," Adesman said. "We don't have data to suggest dietary interventions are any more effective than medications, and there is little, if any, data to suggest dietary interventions are as effective as medications."

The review is published in the February issue of Pediatrics.

ADHD affects an estimated 5 percent to 8 percent of school-aged children. Symptoms, which often persist into adulthood, include inattention, hyperactivity and impulsivity beyond what's normally seen, given a child's age and development.

Understandably, many parents are reluctant to medicate their young children, and so there's lots of interest in alternative treatments, experts said.

"We do find parents are becoming more interested in the possibility of using diets rather than, or as a complement to, medication," Millichap said.

While the first line of treatment for ADHD is medication and behavioral therapy, which uses positive reinforcement to help kids learn to control impulsivity, parents who want to try dietary interventions should be supported in their efforts, Millichap said.

"Diets can be used in the treatment of ADHD, but it's usually not a first choice with most parents," he said. "But some parents prefer it and don't like medications at all. That's one of the reasons for considering the diets. Another is if there are side effects or adverse effects from the medications. Then one might turn to dietary treatments."

Added Adesman: "Families are welcome to explore and pursue alternative approaches, but they need to recognize that oftentimes there is limited research to support or justify their use and the benefits will likely be less substantial than conventional treatment."

More information

The U.S. National Institute of Mental Health has more on ADHD.

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