Diet, Nutrition and ADHD
A recent review article in the December 2016 Barkley ADHD Report by Julia Rucklidge, Ph.D. and Jeanette Johnstone, Ph.D. highlighted the role of diet in the treatment of ADHD.
The role of diet in the expression of ADHD symptoms has been scientifically studied since the 1970s, when following the popular Feingold diet, named after the American pediatrician, was shown to improve patient’s hyperactivity, impulsivity, and inattention. This diet eliminates certain foods and additives such as naturally occurring salicylates, artificial flavors, colors, and petroleum-based preservatives.
Since that time, multiple research studies have been conducted which have yielded mixed results: some controlled trials indicate direct relationships between certain food additives and exacerbation of symptoms, while other controlled trials failed to find a relationship. One reasons for the mixed results might be due to genetic makeup, particularly the histamine H3 receptor gene, which modulates one’s response to certain foods. To put simply, while everyone has this H3 histamine gene, some individuals will have a variant of the gene which will cause some atypical responses to foods and additives. With regard to food color additives, meta-analyses indicate that the overall effect of these ingredients is likely small; however, about 8% of children may benefit from their elimination, and therefore this effect is too substantial to dismiss given the large number of children with ADHD.
Other research has focused on the role of food sensitivities or allergies which influence ADHD symptoms. These studies focus on typical food allergens (i.e. dairy, gluten, barley, soy, eggs, nuts, etc.) Again, research is mixed: some studies found great benefit when eliminating foods that trigger reactions in individuals, while other studies indicate no relationship. Finding food sensitivities or allergies typically requires some kind of elimination diet whereby groups of foods are eliminated for periods of a time. However, caution is given to families who do try elimination diets to discover trigger foods, as significant diet alterations can represent a significant burden on families, offer modest benefits, and could potentially create nutrient deficiencies. The question to ask oneself would be… is it worth it? Is the diet able to be followed with relative ease? Does the new diet substantially impact an individual’s or family’s quality of life positively or negatively? Is there substantial enough improvement in symptoms that make this new diet worthwhile?
International research has also found that the Western diet (high intake of total and saturated fats, refined sugars and sodium, and lower intake of omega-3 fatty acids, fiber, and folate) is correlated with higher rates of ADHD, even after controlling for confounding variables. Avoiding a highly processed diet while focusing on eating whole foods may therefore be a valuable step for some in minimizing ADHD symptoms.
In conclusion, research on diet and the role in symptom expression is likely going to continue to yield murky results until researchers can understand the reason why certain groups of people (through genotyping or some other way of categorizing individuals) respond better to dietary changes. In the meantime, it does appear that eating a wholesome diet, which includes whole foods and minimal processed foods, is likely to be beneficial for decreasing ADHD symptoms.