A recent study used a restricted elimination diet to test whether food allergies were linked to symptoms of attention-deficit hyperactivity disorder (ADHD) in children.
Earlier research has suggested that food allergies may trigger or worsen symptoms of ADHD, but results have not been conclusive.
In the recent study, 100 children (4-8 years old) with ADHD were randomly assigned to follow an elimination diet or a general healthy diet for five weeks. The elimination diet excluded foods that commonly trigger allergic reactions or food intolerances, such as wheat, eggs, tomatoes and dairy products. Instead, the children ate foods that are unlikely to cause reactions, such as rice, white meat and some fruits and vegetables.
After five weeks, 64 percent of the children in the elimination diet group experienced significant improvements in their ADHD symptoms.
These children went on to complete the second phase of the trial, in which different foods were added back into their diets. Over the next four weeks, the researchers tested the effects of foods that induce either low or high levels of immunoglobulin G (IgG) in the blood. IgG is an antibody produced by the immune system that is involved in allergic reactions. The researchers found that levels of IgG in the blood were not related to relapse of ADHD symptoms.
Based on these findings, the authors discouraged the prescription of diets based on IgG blood tests for children with ADHD. However, the study suggested that restricted elimination diets may be useful for testing whether ADHD is induced by certain foods.
Dr Lidy M Pelsser MSc, Klaas Frankena PhD, Jan Toorman MD, Prof Huub F Savelkoul PhD, Prof Anthony E Dubois MD, Rob Rodrigues Pereira MD, Ton A Haagen MD, Nanda N Rommelse PhD, Prof Jan K Buitelaar MD "Effects of a restricted elimination diet on the behaviour of children with attention-deficit hyperactivity disorder (INCA study): a randomised controlled trial." The Lancet Volume 377, Issue 9764 February 5, 2011.