ADHD and Diet – Is there a Link?

This post is part of a series of guest posts on GPS by the graduate students in my Psychopathology course during Spring 2014. As part of their work for the course, each student had to demonstrate mastery of the skill of “Educating the Public about Mental Health.” To that end, each student has to prepare two 1,000ish word posts on a particular class of mental disorders, with one of those focusing on evidence-based treatments for those disorders and the other focused on a particular myth or misunderstanding about mental illness.

______________________________________________

ADHD and Diet – Is there a Link? by Stephanie Cole (with assists by Caleb Lack)

The old saying “You are what you eat” certainly contains truth, but how much? Certainly one’s diet impacts health in a huge variety of ways, but can you cure a severe mental disorder simply by changing your diet? One mental disorder that seems to be a huge target for blaming certain dietary choices as the determinant is ADHD. There are a variety of diets and dietary changes that can be found in books, popular articles and simple searches on the Internet that claim to help or cure ADHD. So, let’s take a closer look at a few of the most commonly discussed diets.

One of the most popular ADHD diets is what is called the Feingold diet. This is a form of an elimination diet where foods containing certain additives are removed and replaced with similar foods that are free of those additives. The additives and dyes that are in foods that are alleged to cause problems are dyes such as Red 3, Red 40, artificial flavors and sweeteners, along with the preservatives BHA, BHT, and TBHQ. There is a lot of controversy surrounding this diet because numerous tests and empirical studies conducted fail to support it. On the other hand, some of the studies did find that certain children and adults with ADHD can become overly hyper after consuming particular food dyes, with the one that seems to cause the most problems being red food dye. Red food dye can be found in soda and anything that is processed that is red. Sometimes it is even put onto red apples that are not organic to make them appear brighter since red is a desirable color for food. It would make sense though, that if someone is sensitive to that particular food dye, then it should be eliminated from the diet.

Another popular diet is simply adding more protein to the diet of someone who is struggling with ADHD. A diet full of protein can reportedly impact brain performance by providing the amino acids from which neurotransmitters are made. Neurotransmitters carry signals to the brain and help with attention and concentration, which are two common things that people with ADHD struggle with. Protein also enhances mental functioning and focus. Often children eat sugary cereals, doughnuts, or pop-tarts for breakfast. Parents, schools, and adults with should consider more high protein options for breakfast and lunch anyway to improve focus and longevity throughout the day. So yes, a diet high in protein can help anyone focus better whether you have ADHD or not, but as far as curing ADHD, there is no evidence to support that. Those curious about this dietary claim and more can read a large literature review that was published by the Nordic Journal of Psychiatry, which researched many of the studies and tests that have been done in relation to diet and ADHD symptoms. A diet high in protein was not linked to any substantial gains in improving ADHD symptoms.

The next diet, which is similar to the Feingold diet but makes fewer universal assumptions, is a food sensitivities and elimination diet. On this type of eating plan, you eat only the foods that do not typically cause allergies, such as lamb, chicken, potatoes, rice, bananas, apples, cucumbers, celery, carrots, parsnips, cabbage, cauliflower, broccoli, salt, pepper, and vitamin supplements. After two weeks you slowly add different things back in and see if it has any effect on behavior. It is also recommended that a doctor or a nutritionist supervise this kind of diet for the most accurate results. In terms of scientific research on this diet, an extremely interesting study was published by the Lancet in 2011. The Impact of Nutrition on Children with ADHD (INCA) study examined carefully the effects of an elimination diet on children with ADHD (this was a large-scale trial undertaken after a small pilot showed promising results). Intriguingly, 64% of the children in the experimental arm (all of whom had ADHD) showed massive drops in ADHD symptoms while on the elimination diet and then a reappearance of symptoms once they were off the elimination diet. They authors concluded that:

Our study shows considerable effects of a restricted elimination diet in an unselected group of 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, provided parents are willing to follow a diagnostic restricted elimination diet for a 5-week period, and provided expert supervision is available. Children who react favourably 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 minimise the burden of the diet. In children who do not show behavioural improvements after following the diet, standard treatments such as drugs, behavioural treatments, or both should be considered.

So, there appears to be benefit to eliminating certain foods from the diet of those with ADHD to help improve symptoms in many but not all children. The study was not without it’s critics (although follow-up research found that one of the major potential concerns – that the dietary changes impacted the family environment in such a way as to cause the improvements seen – was not supported) and the authors have addressed many of the concerns directly. One of the major problems with this approach is getting children and adults to stick with it; another problem is that it can also be very time consuming. Every child is different so at times it could be one ingredient you are looking for that is causing the problems, which can be like finding a needle in a haystack.

In an complementary finding to the idea of food sensitivity impacting ADHD symptoms (if not the full diagnosis), the Southampton Study‘s results are quite interesting. In a cleverly designed study, the researchers “undertook a randomised, double-blinded, placebo-controlled, crossover trial to test whether intake of artificial food colour and additives (AFCA) affected childhood behaviour.” (Plain language summary here.) Their takeaway message from the work was “Artificial colours or a sodium benzoate preservative (or both) in the diet result in increased hyperactivity in 3-year-old and 8/9-year-old children in the general population.” A genetics study of the children involved found strong evidence that those children who reacted poorly to the artificial colors/preservatives had particular polymorphisms that moderate histamine reaction (again, plain-ish language summary here). The accompanying editorial opined:

The links are clear, and the paper is a watershed, although still falling far short of definitive proof. As with every breakthrough, more questions emerge than are answered…but there is no cost to health or safety in giving up artificial food colors. It certainly appears that over and above this set of studies, the cumulative evidence is sufficient for society to demand adherence to the precautionary principle and to… restrict the use of artificial dyes, at least in foods that target children.

A recent review of artificial food coloring’s (AFC) impact on ADHD also concluded that:

Recent data suggest a small but significant deleterious effect of AFCs on children’s behavior that is not confined to those with diagnosable ADHD. AFCs appear to be more of a public health problem than an ADHD problem. AFCs are not a major cause of ADHD per se, but seem to affect children regardless of whether or not they have ADHD.

Together, these results suggest that a certain group of children (those with particular polymorphisms that cause a larger than normal release of histamines in response to certain foods) can have quite negative impacts on their behavior from ingesting certain substances. The impact might even be large enough for these certain children be diagnosed with ADHD, and could be mitigated by avoidance of particular ingredients in food.

As in all health care, the decisions made about food and how it affects ADHD need to be based on evidence, not anecdote. Jumping into whatever new diet is being highly publicized as a “miracle cure” will certainly be problematic and likely ineffective. So, what to do?

At this point in time, there appears to be a decent amount of literature at this point that suggests a link between ADHD symptoms and food sensitivities or allergies in some (but not all) children who can be diagnosed with ADHD. While medication and behavioral therapies will undoubtedly remain the treatment of choice for most parents and providers, it is not unreasonable to suggest that a significant number of children may benefit from a dietary intervention (both for ADHD symptoms and perhaps even for sleep problems). A restricted elimination diet (RED) like the one used in the INCA study appears to be the best bet right now, but comes with it’s own set of difficulties. There’s not a magic bullet out there to “fix” everyone’s symptoms, unfortunately, but as more research is conducted we may have a better idea of what treatment will work with a particular child or adult with ADHD – medication, psychosocial therapies, dietary changes, or some combination.