Lancet Study: Elimination Diets Success in over 50% of ADHD Kids

The Lancet will soon publish the results of the 'Impact of Nutrition on Children with ADHD (INCA)' study. This is yet another, very well done, study on elimination diets and ADHD. The results of this study reported two findings.

The first finding was that a strict elimination diet improved symptoms of hyperactivity, impulsive behavior, oppositional behavior and inattention. The second finding was that the benefits in these behaviors did not correspond to an increase in blood IgG levels ( a blood measure of an allergic reaction) in the kids that had behavioral changes. The second finding is interesting because it shows us that testing for IgG will not always tell us that a child has a food allergy.

Of the 41 (82%) of 50 children in tested in the restricted diet group, 32 (78%) had improved behavior as measured by both questionnaires and pediatrician evaluation. Thirty of the kids that had improved improved symptoms on the very restricted diet were then 'challenged' with foods such as chicken egg, peanut, soy, milk, fish, and wheat. Nineteen of the thirty, 63%, had a relapse of symptoms.

If we go back to the original number of 41 kids we see that almost half of them seemed to have symptoms that improved when they did not eat certain foods and worsened when they ate them. This study involved different individual diets for each participant but all children started on a diet of nothing but rice, meat, vegetables, pears, and water, the diet lasted 5 weeks and was sometimes complemented with potatoes, fruits, and wheat.

The elimination diet is one of the few treatment that has been shown in a clinical trial to markedly improve Oppositional Defiance Disorder. Given that this ADHD co-morbidity is especially disruptive to families and schools, the findings of this study may be the answer that many parents and teachers have been longing for.

As is often the case in the study of Inattentive ADHD, the measurements that the researchers looked at to gauge improvement in attention were not as exacting as the measurements taken for the symptoms of impulsive behavior, oppositional behavior or hyperactivity. It is therefore not clear from this study how much benefit was derived from the restrictive diet with regards to improving attention.

The recommendations that the authors give at the end of this study differ enourmously from the current American Academy of Pediatrics and the American Psychiatric Association recommendations. The study recommendations are a radical departure from the manner in which pediatrician and psychiatrist have viewed a child's diet, and it's role in symptom control, in the past. What they recommend is that ALL kids with ADHD should FIRST be treated with a dietary intervention and only if this does not help should behavioral therapy and drug therapy be initiated.

This is what they say, in their own word. "Our study shows considerable effects of a restricted elimination diet in children with ADHD, with equal effects on ADHD and oppositional defiant disorder. Therefore, we think that dietary intervention should be considered in all children with ADHD... 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... In children who do not show behavioural improvements after following the diet, standard treatments such as drugs, behavioural treatments, or both should be considered."

These findings tell us that diet can help the symptoms of ADHD but the authors, while proposing the same treatment, differ from the Feingold camp in their beliefs that it is artificial dyes and preservatives that are the culprits. If I am understanding the study findings, the authors believe that certain foods cause kids to have reactions to them and that they may be foods that are not necessarily full of artificial ingredients but foods that the particular child is sensitive to.

If you would like to read the entire paper, the link is:

A description of the diet is below.

The INCA Restricted Elimination Diet

This individually composed Restricted Elimination Diet (RED), which had to be followed for 5 weeks at the
most, was based on the few foods diet as described by Hill and Taylor [1]. Assuming that children might
show ADHD symptoms after eating any kind of foods, the few foods diet consisted only of a limited number
of hypo-allergenic foods, like rice, turkey, lamb, a range of vegetables (lettuce, carrots, cauliflower,
cabbage, beet), pears and water [2]. In our study the RED was complemented with specific foods like
potatoes, fruits, and wheat, to be eaten according to a compulsory intake schedule, in order to compose an
elimination diet as comprehensive as possible for each individual child, thus making the intervention less
incriminating for child and parents [3,4]. If the parents reported no behavioural changes by the end of the
second week, the RED was further restricted and gradually limited to the few foods diet: all other foods
were prohibited, but vegetables, rice and meat were allowed every day, in unlimited amounts. Calcium was
supplied daily via non-dairy rice drink with added calcium, ensuring that children were not at risk for
nutrient deficiencies

Let me know what your opinion is. I would love to hear from you.


  1. So if I read this study correctly, it was for kids with ADHD with hyperactivity, not inattentive type? And it was a short term study, no long term effects of such a diet? I hope they do a follow up.

    We're going on vacation and then we'll give this a try. Sounds daunting, but incredibly healthy for the entire family really. Will you try this?

  2. Hey,

    I too see it as a monumental task to try and implement such a restrictive diet but I am trying to see if I can eliminate some things (milk products, eggs products), one by one to see if I notice any difference. You are right! They really looked more at hyperactive, impulsive and oppositional symptoms and less at the inattentive component.

    Thanks for writing. Tess

  3. I love this sentence: "What they recommend is that ALL kids with ADHD should FIRST be treated with a dietary intervention and only if this does not help should behavioral therapy and drug therapy be initiated.". My daughter has ASD, but I also believe that diet has a major impact on her behavior found this fascinating to read. Thank you for posting!


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