Are dietary interventions effective for treating ADHD? For many parents and professionals, trying to parse through the different claims about the impact of diet on ADHD has been challenging and confusing. At this point, substantial research on how dietary interventions impact ADHD has accumulated and several meta-analyses of this work have been published. Recently, a review of several meta-analyses of dietary interventions for ADHD was published [Research review: The role of diet in the treatment of attention-deficit/hyperactivity disorder — an appraisal of the evidence on efficacy and recommendations on the design of future studies]. In this paper, the authors summarize findings across 6 different meta-analyses of the impact of diet on ADHD to provide a high level summary of the best available evidence to date.
Types of dietary interventions
Three types of dietary interventions were reviewed — Restricted Elimination Diets (RED), Artificial food coloring exclusion (AFCE), and supplementation with free fatty acids (SFFA). Although other types of supplements beyond free fatty acids have been investigated, the authors felt there was not sufficient research on any single approach to include in their summary.
1. Restricted elimination diets (RED) — There are 2 different approaches to implementing this diet. In one approach, the child is placed on an extremely restricted diet, e.g., rice, turkey, a range of vegetables (lettuce, carrots, cauliflower, cabbage, beets), pears and water; this is sometimes referred to as the Few Food Diet. When a reduction in ADHD behaviors results — this would generally occur within 2–3 weeks if the diet is going to have a positive effect — new foods can be added back one at a time to see if they are well-tolerated or lead to an increase in problem behaviors. Alternatively, particular foods that are suspected to exacerbate a child’s symptoms may be removed one at a time to see if the child’s behavior improves.
2. Artificial food coloring exclusion (AFCE)- As the title indicates, this involves efforts to remove all artificial food colorings from a child’s diet, e.g.,Yellow #6, Yellow #5, Sodium Benzoate, Blue #2, etc., and observing whether this is associated with a reduction in ADHD behaviors. Carefully conducted trials have demonstrated that AFC’s – in amounts children could typically consume – can increase ADHD symptoms in many children.
3. Essential fatty acid supplementation — Certain fatty acids, e.g., Omega 3 and Omega 6, promote neural functioning. These fatty acids are called essential because they are not synthesized in the body and must be ingested. Children with ADHD may have lower levels of essential fatty acids relative to peers and several studies have demonstrated a link between low levels of EFAs and the severity of ADHD symptoms. Studies investigating the benefits of fatty acid supplementation for youth with ADHD raise fatty acid levels by administering capsules containing the fatty acids or sometimes by introducing diets rich in fish products.