What effects do lifestyle choices such as diet and nutrition habits have on ADHD? On one end of the continuum you have advocated for strict elimination diets that remove all food additives such as artificial food coloring and preservatives, while on the other side of the issue, people believe that diet and nutrition do not contribute to or change symptoms of ADHD at all. Certainly, it is clear that a healthy, nutrient-rich diet, low in saturated fats and processed sugars is overall good for your health. But does what we eat affect behaviors and learning outcomes? In other words, how to we determine the age old problem of nature vs. nurture? How much of behavior, and in this case behavior that is associated with ADHD, is inherent in our biology and how much can we alter through the manipulation of external factors such as diet and nutrition? In this article, we will examine the breadth of available research that is out there on specific dietary factors as they relate to symptoms associated with ADHD.
Overall, there has been a relative scarcity of conclusive studies examining dietary factors in children with ADHD. Further complicating the issue is that of the studies that have been done, many of them use very small sample sizes that make interpretation of the data and extrapolation of the general population difficult. Many other studies fail to fully control for other factors that may be contributing to ADHD symptoms. That is not to say that all studies fall into this category: there are a few recent studies that are now beginning to shed light on the influences of diet on behavior in both healthy (control) groups and ADHD groups.
Diet and food additives
Today, the diet of many people around the world is rich in food additives including preservatives and artificial colors and flavorings. Since the mid-1800s when the first synthetic dyes were discovered, artificial food colorings have been used and food additives and are now widely added to foods. Take most any product out of your pantry or fridge and you will likely find names like “FD&C red No. 3” or “blue 1 lake” on the list of ingredients. Also common as additives are preservatives, that is, chemicals added to keep food from spoiling for longer periods of time. Common preservatives used today are benzoates (commonly found in acidic foods like pickles and mustard), and nitrites (used to preserve meat products such as bacon and ham). Use of these and other additives is regulated with respect to which chemicals are allowed and how much can be added to foods, by agencies such as the USDA (United States Department of Agriculture) and FDA (Food and Drug Administration).
So, with all of the chemicals added to foods on a regular basis, and oversight by federal regulatory agencies, why is there controversy about the safety of these chemicals and what is the implication in symptoms of ADHD? Much of the initial finger pointing at food additives came from a pediatric allergist, Dr. Benjamin Feingold, who proposed back in the early 1970s that chemical additives such as artificial food coloring and preservatives caused hyperactivity in children. In addition, there are a few studies which draw conclusions that link exacerbation of ADHD symptoms to artificial food coloring or preservatives. One study in particular1 examined a collection of research on the connection between ADHD and artificial food colors (AFCs). The existing research seemed to show a connection between AFCs and an inhibition of a particular enzyme called SULT1A. Why is this enzyme important to ADHD? Well, inhibition of SULT1A has been shown to affect neurotransmitters such as noradrenaline and dopamine, the same neurotransmitters whose activity is modulated by powerful stimulant medications like methylphenidate that have been used to treat ADHD for decades. Individual studies found that AFCs led to inhibition of SULT1A. However, after a thorough review of this study by an independent research group1, it was found that all of the diets used in the study, even the placebo diet that was free of AFCs, had other SULT1A inhibitors in it. In fact, the new study found that natural SULT1A inhibitors were found in AFCs, but also in natural substances and in many foods. Based on this data, it was not possible to discern how much of the inhibition was caused by AFCs and how much by naturally occurring substances. The conclusions of several studies linking AFCs and other additives to symptoms of ADHD seem to also be plagued by difficulties like this one1,7. Still, more studies having proper controls and experimental plans seem to show conflicting conclusions as to whether AFCs have an effect on symptoms of ADHD2,3.
However, a few comprehensive, recent studies that looked into the controls and experimental setups, seem to overwhelmingly agree with a conclusion about AFCs and preservative food additives 1,4-7. The consensus is that a very small percent of children are very sensitive to certain additives. Think about this like a food allergy, where some children react very badly to certain foods, but it does not mean that those foods in general cause immune system problems. Further conclusions were that in those sensitive children, some of which have AHDH, the particular additives may worsen symptoms. As far as research goes, that is a pretty weak link. Still, there may be benefits (for ADHD or otherwise) to eliminate certain additives from the diet, but one has to weigh these potential benefits to a very small number of children, against the difficulties in adhering to a strict elimination diet.
Sugar and Hyperactivity
Parents of children, with or without attention/hyperactivity symptoms, have long since believed that children are more active after the consumption of sugar. We have all heard the cautionary advice of well-intentioned parents and grandparents warning not to give children too much sugar or they’ll be “bouncing off the walls”. How much truth is there to this advice? There is certainly biological evidence to back the claim. After eating a meal laden with simple sugars, the body responds by releasing insulin, the hormone that controls blood sugar levels. After a surge in insulin levels, there is a period of relative hypoglycemia. This triggers the body to release a chemical called epinephrine, which is associated with a stimulant-like activity.
Several studies have been done to test the connection between consumption of sugar and increased cognitive or behavioral issues in children. While there are some conflicting results, the majority of the studies surprisingly conclude either a marginal connection or none at all. One particular study tested the hypothesis that it is the parent’s perception and not actually the child’s behavior that changes after sugar consumption8. In this study, parents were told that their children were given either a high sugar drink or a placebo. However, both groups of children were given the placebo. Parents who were told that their children drank the sugar drink reported more hyperactivity in their children. In other words, it may be that parent’s expectations about their children’s diets are negatively affecting their outlook on actual behavior.
Similar to the findings with regard to AFCs and other additives, comprehensive reviews of the literature conclude that sugar does not have a significant effect on the behavioral or cognitive function of most children, including those with ADHD9. However, there are some children who are sensitive to sugar and the significance of this sensitivity on ADHD symptoms cannot be ruled out the by research done to date. In addition, the risks associated with a diet high in simple sugars include obesity, diabetes, and increased triglycerides. For these reasons, in addition to possible individual sugar sensitivities that may predispose children to hyperactivity, consumption of simple sugars should be restricted in any healthy eating plan. This may be especially true for children with impulsivity issues who may be at higher risk for unhealthy eating habits and obesity.
Everything in Moderation
Given the conflicting information out there, you may be confused about what to do. If your child has ADHD, should you opt for a total elimination diet, not consider dietary information at all, or somewhere in between? There is no conclusive evidence to show that dietary factors cause ADHD. However, the research does show that a subset of “sensitive” individuals can have an exacerbation of symptoms from particular food additives or refined sugars. With that in mind, you have to weigh the pros and cons of an extreme lifestyle change like a total elimination diet. Remember that ADHD is often associated with anxiety in children. An elimination diet can further bring about anxiety if a child feels that she cannot go out to eat with friends or he thinks that he is not seen as “normal” when other kids are eating in school. On the other hand, there may be some benefit to eliminating certain triggers that your child may be sensitive to. The key is to find the middle ground where your effort to control symptoms is not putting undue stress on your son or daughter, but you are still advocating for a healthy diet. So, don’t stress if your son ate a cupcake after school and now has to do some math homework, or your daughter drank juice riddled with Red No. 40. Just make sure that processed foods and sugary snacks are the exception and not the rule, and are part of an overall healthy diet.
- Eagle, K. ADHD impacted by sulfotransferase (SULT1A) inhibition from artificial food colors and plant-based foods. 2014. Physiol. Behav. Aug; 135: 174-9.
- Lok, K.Y. et. al. Food additives and behavior in 8- to 9-year-old children in Hong Kong: a randomized, double-blind, placebo-controlled trial. 2013. J Dev Behav Pediatr. Nov-Dec.; 34(9): 634-50.
- McCann, D. et. al. Food additives and hyperactive behavior in 3-year-old and 8/9-year-old children in the community: a randomized, double-blinded, placebo-controlled trial. Lancet. Nov 3; 370(9598): 1560-7.
- Sonuga-Barke, E.J. et. al. Nonpharmacological interventions for ADHD: systematic review and meta-analyses of randomized controlled trials of dietary and psychological treatments. 2013. Am J Psychiatry. Mar; 170(3):275-89.
- Millichap, J.G. and Yee, M.M. The diet factor in attention-deficit/hyperactivity disorder. 2012. Pediatrics. Feb; 129(2): 330-7.
- Nigg, J.T. et. al. Meta-analysis of attention-deficit/hyperactivity disorder or attention-deficit/hyperactivity disorder symptoms, restriction diet, and synthetic food color additives. 2012. J Am Acad Child Adolesc Psychiatry. Jan;51(1): 86-97.
- Arnold, E.L. et. al. Artificial Food Colors and Attention-Deficit/Hyperactivity Symptoms: Conclusions to Dye for. 2012. Neurotherapeutics. 9: 599-609.
- Hoover, D.W., and Milich, R. Effects of sugar ingestion expectancies on mother-child interactions. 1994. J Abnorm Child Psychol. Aug;22(4): 501-515.
- Wolraich, M.L. et. al. The effect of sugar on behavior or cognition in children. A meta-analysis. 1995. JAMA. Nov;274(20): 1617-21.
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