Restricted Diets for Children with ADHD

Findings from a new study published in The Lancet indicate that the restricted elimination diet should be part of the standard of care for all children with attention-deficit hyperactivity disorder (ADHD).

In their previous research, Jan Buitelaar, PhD, of Radboud University Nijmegen Medical Centre in The Netherlands and colleagues postulated that ADHD might be an allergic or non-allergic hypersensitivity disorder in some children, triggered by any types of food that can cause allergic reactions. In the new study, a group of 50 children with ADHD between the ages of four and eight were given the elimination diet, and 50 controls were given instructions for a general healthy diet for five weeks.

Children in the intervention group reacting favorably to the restricted diet were assigned to a second phase in which two different groups of foods were added to the elimination diet, one containing foods that induced high levels of immunoglobulin G (IgG) in the blood (high IgG food), and the other consisting of low IgG foods. The food groups were different for each child based on his or her blood test results. The purpose of this phase was to investigate whether IgG blood tests are useful to identify foods that trigger ADHD.

The researchers found that in the first part of the study, children in the intervention group showed significant improvements in their symptoms as demonstrated by the ADHD rating scale. The oppositional defiant disorder symptoms, also present in half the children, also decreased.

Although previous studies have shown a connection between food and ADHD, the cohorts in these trials were small or included only children known to have an allergic constitution, preventing the results from being applicable to the general population. This study, according to the authors, “shows comparable effect sizes in patients who are representative of the general ADHD population, supporting the implementation of a dietary intervention in the standard of care for all children with ADHD.”

The prescription of diets on the basis of IgG blood tests should be discouraged, they added.

“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 5-week period, and provided expert supervision is available,” Buitelaar and colleagues wrote. “Children 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 children who do not show behavioral improvements after following the diet, standard treatments such as drugs, behavioral treatments, or both should be considered.”

In a related comment published in The Lancet, Jaswinder Kaur Ghuman, MD, of the University of Arizona stated that an elimination diet trial should be implemented only under the supervision of the child's primary health-care provider and a nutritionist to ensure that growing children do not suffer from nutritional deficiencies with the restricted diet.

“Diagnosing food sensitivity is complex, can take several weeks, and can be burdensome for families to implement. The restricted diet can be tried for 2-5 weeks. If there is benefit, the restricted foods can be added back weekly, one food component at a time, to identify the problem foods to be excluded from a less restrictive permanent diet,” she wrote. “In my opinion, a stringent elimination diet should not continue for more than 5 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.”