ADHD Diet Plan Improves Behaviour? No, not really. Read the small print.

Every newspaper, weekly magazine and blog seems to have published a headline about an "elimination diet" that helps kids with ADHD (Attention Deficit Hyperactivity Disorder) control behaviour. "Change their diet, and their behaviour changes." Yep, as easy as that, and here is the scientific proof it works. No, not really. After years and hundreds of studies showing this idea that ADHD is caused by and can be cured by diet IS NOT TRUE, suddenly there is a study that shows it is true. How can his be? Well, read on and I'll tell you.

What we know from past research is that parent and teacher expectations of the effects of diet on kids with ADHD (Attention Deficit Hyperactivity Disorder). In previous studies we did things like tell one group of parents that kids were eating sugar filled candies and we wanted to know what the effect was. Well, the kids went crazy! And then another group of kids were given candies with no sugar ...hmmmm. No effect. Then we find out the candies were all the same. And sometimes we have done similar experiments when none of the candies had sugar and so on and on and on. What happens are a couple of things: Parents and teachers change their behaviour to match what they think is happening. When the kids are getting the food they think should quiet the kids down the parents become more structured and organized, and also interpret the kids behaviour that way. And the parents and teachers told that their kids we getting the food with the harmful and ADHD causing ingredients acted in a way to excite the kids, over-reacting, and saw many behaviours that were similar to the first group as signs of ADHD. This is sometimes called observation bias or confirmation bias. We see and note what we expect. We all do this, and a good scientific study avoids this by "blinding" the study. In a good study no one knows who is getting what medicine, no one knows what group is getting the treatment, what group is not.

On top of this problem is the placebo effect. Kids told that a pill containing nothing is really going to help them feel like it has and act like it has. And the same goes for parents.

These are what, for decades, we have found to be happening when studies have shown a relationship between food additives, colouring, sugar, wheat and so on and behaviour in children and adolescents with ADHD (Attention Deficit Hyperactivity Disorder). We see parents changing their family schedule to fit a new diet they think will cure their child's ADHD, they put charts up, measure food, insist time schedules are met and are in constant contact with the school and teacher about the diet. Everyone's expectations change, everyone's behaviour. and somehow they all think it's the diet. t isn't, it's the placebo effect plus confirmation bias plus a touch of behavioural expectation change.

Research has been clear that there is no effect on ADHD by a restrictive diet, except in those cases where a specific child might have a specific allergy or reaction to some food or ingredient. And those cases are few and far between. That doesn't mean your child may not have a food allergy that causes discomfort and thereby causes acting out. Ask your MD about that. But ADHD is a genetic disorder relating to the frontal lobes of the brain, it's an executive disorder, and it isn't caused by junk food.

That doesn't mean your kid should eat junk food. A child who eats a crappy diet is going to feel crappy. But potato chips will not make him a serial killer.

So back to this study. If you actually read it, which apparently none of the great newspaper science reporters or the million and one bloggers have, you will note some very serious problems. Let's start with: Nothing was blinded. Parents knew who was eating what, teachers knew. And I expect the kids knew. So what are we seeing from the results? I'm afraid nothing more than the combined effects of placebo effect (a healthy diet will calm you down, lets eat a healthy diet) and confirmation bias (see, he really has calmed down now he doesn't eat that junk)....oh, and a good helping of positive effect from the behavioural efforts of parents and teachers making sure diets were followed. (Behaviour changes when it is watched.)

What we have in these results isn't proof that decades of research was wrong, but instead proof that it was right. Diet is unlikely to have a significant effect on your child's behaviour. But changing your behaviour, organizing your life, structuring meals, changing your expectations, interpreting behaviours more positively and communicating actively with the school actively WILL have a significant effect on your child's behaviour. Note that those are the components of a good ADHD intervention program that experts like Dr. Russell Barkley have suggested for years.

I know, I am a curmudgeon. I doubt everything, so I came prepared with the opinions of other experts in the field:

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." Dr. Leo noted the lack of strict monitoring of compliance with the dietary recommendations and the lack of information on the exact makeup of the diet. Like me 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."

Then there is Michael Daines, MD, a pediatric allergist and immunologist at the University of Arizona, who called the study "interesting, but flawed," pointing to the lack of blinding in the study groups, which would potentially affect all of the data. And 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. More on these opinion can be found at:

Medical News: ADHD Diet Plan Gets Mixed Reviews - in Pediatrics, ADHD/ADD from MedPage Today

What I regret is that the many newspaper articles and blogs that reported this (more often than not with ads on the side of the web page advertising miracle ADHD cure diets!) failed repeatedly to note the problems with the studies, and failed to note that decades of other studies found the opposite results. odd to leave those issues out. I am surprised the Vancouver Sun hasn't made this a front page article with it's usual lack of analysis. But it's only been a couple days. I suggest we all write to our local papers and ask them to pay more for a science editor, and maybe get someone with a science degree.


The ADHD blog is not offered as medical advice or as a means of diagnosing or treating ADHD or any other disorder. My recommendations: Don't go on-line and take an ADHD "test." The diagnosis of ADHD is complex and involves not just looking for symptoms of ADHD, which is all that those “tests” do, but also involves ruling out other disorders that might look just like ADHD. Often individuals who think they have ADHD have other disorders, and may have co-morbid disorders such as depression, anxiety or OCD. A simple check off sheet of “symptoms” doesn’t differentiate these. So avoid these on-line "tests" which are nothing more than a collection of symptoms. You need to see a licensed or registered professional for a real diagnosis. Medical doctors can diagnose ADHD, but the diagnosis is complex and often they will make a referral to a Registered Psychologist for a full understanding of a patient’s symptoms. You can obtain a referral for a psychologist with expertise in ADHD from the British Columbia Psychological Association (BCPA).

In my practice I offer Attention Deficit Hyperactivity Disorder (ADHD) assessment and treatment services for individuals, couples, families, children and adolescents in the Burnaby, Vancouver, Coquitlam, Port Moody, New Westminster and Maple Ridge areas of the lower mainland. This includes neuro-developmental assessments, psycho-education, cognitive rehabilitation for problems with memory and concentration and cognitive behaviour therapy. I also provide diagnostic assessments for autism and Asperger's Disorder in my Burnaby office.

My web page lists a number of resources you can make use of yourself in dealing with Attention Deficit Hyperactivity Disorder (ADHD). Please visit it at or one of my other sites at either Psychology Today, AAMFT, PSYRIS or my professional site. Please feel free to call if you have questions about ADHD or other cognitive issues.

Dr. Jim Roche
Registered Psychologist, British Columbia 01610