Food and Behaviour Research

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ADHD Diet Plan Gets Mixed Reviews

By Kristina Fiore, Staff Writer, MedPage Today


This article shows the wide variety of reactions to a study published in the Lancet (see Pelsser et al 2011) which adds to the existing evidence that diet can influence ADHD symptoms in many children.

That evidence is now substantial - and yet many critics continue to deny it - insisting that benefits for all children with ADHD must be shown to result from exactly the same dietary intervention - and that the intervention must be 'double-blind'. 

ADHD is known to be a purely descriptive diagnosis, with many possible causes for the 'symptoms'. Adverse food reactions in children that increase their ADHD symptoms have already been well-documented in many double-blind trials, but these reactions are known to differ between individual children.

Dietary interventions are never easy to implement. Professional assistance is usually needed to ensure that any 'special' diet will still provide a healthy balance of all essential nutrients - but given that most 'ordinary' diets consumed by children in developed countries do not do this, it might be rather more helpful to give our health professionals better training in nutrition and its importance for the brain as well as the body.

Clinicians who are open to the actual evidence on this controversial subject may find useful the clinical protocol published 10 years ago by leading UK researchers, which acknowledged the importance of dietary modifications for some ADHD children. See 

Those with closed minds will of course carry on denying the abundant evidence for the importance of diet to mental as well as physical health.

See also the related news article and FAB comment:

And for more information on this subject, please bookmark the following lists of research articles, which are regularly updated.

A limited diet that focuses on a few selected foods including rice, meat, and vegetables may provide symptom relief for children with attention deficit/hyperactivity disorder, researchers said, but skeptics question the validity of their study.

After five weeks, 64% of those on a restricted diet had significant improvement in symptoms; no improvement was seen in those who were not on the restricted diet, Lidy Pelsser, MD, of the ADHD Research Center in Eindhoven, the Netherlands, and colleagues reported in The Lancet.

"We think that 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," they wrote.

In a comment to ABC News and MedPage Today, David Rosenberg, MD, a child psychiatrist at Wayne State University, said that the finding "is not unexpected and lends additional evidence that diet and other environmental factors may be important in ADHD."

He said he would be willing to try a restricted elimination diet, "and in some ways we already do this for certain patients and with their parents, although not necessarily the systematic approach studied here."

Others contacted by ABC News and MedPage Today, however, were skeptical of the findings.

Harvey Leo, an allergist and immunologist at the University of Michigan, said in an e-mail, "There are severe limitations to this study, and after reviewing the current paper, I do not think any of the data presented have any true validity."

He noted the lack of strict monitoring of compliance with the dietary recommendations and the lack of information on the exact makeup of the diet.

He said the benefits observed were likely due to enrollment in the study and rigorous monitoring -- rather than an effect from diet modification -- because children with ADHD respond to structure and organization.

"If the parent was truly committed to the diet," Leo said, "I think the child would see some benefit in behavior."

Michael Daines, MD, a pediatric allergist and immunologist at the University of Arizona, called the study "interesting, but flawed," pointing to the lack of blinding in the study groups, which would potentially affect all of the data.

Also wary of the findings was William Pelham, PhD, a psychologist at the University of Buffalo, who cited studies conducted over the past 30 years that have failed to support a consistent relationship between dietary manipulations and ADHD symptoms.

"One open study allegedly demonstrating a relationship does not change my mind," he wrote in an e-mail.

Foods can cause physical reactions, such as eczema and asthma, that affect other organs, so it's been suggested that what patients eat may also affect the brain. Thus, diets built around hypoallergenic foods are believed by some to be effective for ADHD.

Pelsser and colleagues conducted the Impact of Nutrition on Children with ADHD (INCA) Study, a randomized controlled trial that enrolled children ages 4 to 8 from the Netherlands and Belgium who'd been diagnosed with the disease.

The children were assigned to either five weeks of a restricted diet, or were given written instructions about a healthy diet and placed on a waiting list. The researchers used the few-foods diet, which includes rice, meat, vegetables, pears, and water, and can be complemented with specific foods such as potatoes, fruits, and wheat.

After the initial five weeks, those in the restricted-diet group who had improved ADHD symptoms entered a four-week, double-blind, crossover food challenge phase, in which they ate high-IgG or low-IgG foods to assess specific reactions.

A total of 100 children were enrolled; most were boys and the mean age was 6.9.

The researchers found that at the end of the first, five-week diet phase, symptoms of ADHD and oppositional defiant disorder significantly improved in 64% of children in the diet group; there was no improvement among controls.

The mean difference in ADHD Rating Scale (ARS) score after five weeks was significantly lower in the diet group than in the control group for both masked pediatrician and unmasked teacher ratings (P<0.0001).

Scores on the abbreviated Conners' scale (ACS) -- which assesses hyperactivity, impulsivity, attention, mood, and temper tantrums -- were also significantly lower in the diet group for parent and teacher ratings (P<0.0001).

The researchers saw no increase in IgE levels associated with clinical response, which suggests that the underlying mechanism of food sensitivity in ADHD is nonallergenic.

In the second phase of the study, the 30 children who responded to the restricted diet proceeded to the challenge phase, which involved two weeks of three high-IgG and three low-IgG foods added to their regimen.

The researchers saw that 19 of these children (63%) had a relapse in ADHD symptoms after one or both challenges.

In his comments, Daines said that the fact that one-third did not regress makes "the interpretation (of the study findings) even more suspect."

The IgG levels produced in response to certain foods didn't predict which ones might lead to a negative effect on behavior, as an equal number of low and high IgG challenges resulted in relapse, the researchers said.

"These results suggest that use of IgG blood tests to identify which foods are triggering ADHD is not advisable," they wrote, noting that in complementary care, the tests are offered even though there is no evidence for their efficacy.

Added Rosenberg, "It is not surprising that IgG blood tests did not predict relapse of ADHD symptoms as this is a multifactorial, extremely heterogeneous illness. However, it is an important lead and suggests that diet, immunologic, and other factors are clearly involved in ADHD."

The researchers acknowledged that the study may have been limited because the parents, teachers, and researchers couldn't be blinded to the diets.

Still, they concluded that restricted diets may be considered in children with ADHD, and that those "who react favorably to this diet should be diagnosed with food-induced ADHD and should enter a challenge procedure to define which foods each child reacts to, and to increase the feasibility and to minimize the burden of the diet."

In an accompanying comment, Jaswinder Kaur Ghuman, MD, of the University of Arizona in Tucson, wrote that the study was "well-designed and carefully done, showed benefit with a supervised elimination diet, and provides an additional treatment option for some young children with ADHD."

But Ghuman noted that 36% of the children either didn't respond to the diet or were noncompliant, so it would be "helpful to know which children can be predicted to respond to the diet."

He also cautioned that a "stringent elimination diet should not continue for more than five weeks without obvious benefit because of the time, effort, and resources required to implement the restricted diet and because long-term effects of dietary elimination on the child's nutritional status are not known."

Ghuman called for more research on the specific foods responsible for hypersensitivity reaction.