Diet and ADHD, Reviewing the Evidence: A Systematic Review of Meta-Analyses of Double-Blind Placebo-Controlled Trials Evaluating the Efficacy of Diet Interventions on the Behavior of Children with ADHD

Abstract

IntroductionAttention-deficit/hyperactivity disorder (ADHD) is a debilitating mental health problem hampering the child’s development. The underlying causes include both genetic and environmental factors and may differ between individuals. The efficacy of diet treatments in ADHD was recently evaluated in three reviews, reporting divergent and confusing conclusions based on heterogeneous studies and subjects. To address this inconsistency we conducted a systematic review of meta-analyses of double-blind placebo-controlled trials evaluating the effect of diet interventions (elimination and supplementation) on ADHD.MethodsOur literature search resulted in 14 meta-analyses, six of which confined to double-blind placebo-controlled trials applying homogeneous diet interventions, i.e. artificial food color (AFC) elimination, a few-foods diet (FFD) and poly-unsaturated fatty acid (PUFA) supplementation. Effect sizes (ES) and Confidence intervals (CI) of study outcomes were depicted in a forest plot. I2 was calculated to assess heterogeneity if necessary and additional random effects subgroup meta-regression was conducted if substantial heterogeneity was present.ResultsThe AFC ESs were 0.44 (95% CI: 0.16–0.72, I2 = 11%) and 0.21 (95% CI: -0.02–0.43, I2 = 68%) [parent ratings], 0.08 (95% CI: -0.07–0.24, I2 = 0%) [teacher ratings] and 0.11 (95% CI: -0.13–0.34, I2 = 12%) [observer ratings]. The FFD ESs were 0.80 (95% CI: 0.41–1.19, I2 = 61%) [parent ratings] and 0.51 (95% CI: -0.02–1.04, I2 = 72%) [other ratings], while the PUFA ESs were 0.17 (95% CI: -0.03–0.38, I2 = 38%) [parent ratings], -0.05 (95% CI: -0.27–0.18, I2 = 0%) [teacher ratings] and 0.16 (95% CI: 0.01–0.31, I2 = 0%) [parent and teacher ratings]. Three meta-analyses (two FFD and one AFC) resulted in high I2 without presenting subgroup results. The FFD meta-analyses provided sufficient data to perform subgroup analyses on intervention type, resulting in a decrease of heterogeneity to 0% (diet design) and 37.8% (challenge design).ConclusionConsidering the small average ESs PUFA supplementation is unlikely to provide a tangible contribution to ADHD treatment, while further research is required for AFC elimination before advising this intervention as ADHD treatment. The average FFD ES is substantial, offering treatment opportunities in subgroups of children with ADHD not responding to or too young for medication. Further FFD research should focus on establishing the underlying mechanisms of food (e.g. incrimination of gut microbiota) to simplify the FFD approach in children with ADHD.

CIMMYT Series on Carbohydrates, Wheat, Grains, and Health: Role of Carbohydrates and Grains in Nutrition and Neurological Disorders: Headache, Attention Deficit Hyperactivity Disorder, and Depression,

“…In a small sample of obese women, nondepressed elderly women consumed more CHOs than those who were depressed (101,102). Depressed individuals in a small Turkish study consumed 55% of "research is required for AFC (artificial food color) elimination before advising this intervention as ADHD treatment" for children (75).…”

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“…In a small sample of obese women, nondepressed elderly women consumed more CHOs than those who were depressed (101,102). Depressed individuals in a small Turkish study consumed 55% of "research is required for AFC (artificial food color) elimination before advising this intervention as ADHD treatment" for children (75).…”

“…Although these dietary interventions for managing ADHD have been proposed by practitioners of both Western and traditional Chinese medicine, limited research exists on the efficacy and safety of dietary intervention as an adjunct to conventional medications (40,49,(76)(77)(78)(79). To date, findings suggest elimination diets and fish oil supplementation may hold promise in certain cases (40,75,76) and may offer treatment opportunities for subgroups of children with ADHD who do not respond to or are too young for medication (75).…”

Micronutrients and Diets in the Treatment of Attention-Deficit/Hyperactivity Disorder: Chances and Pitfalls

“…Since blood levels of docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA) and arachidonic acid (AA) have been found to be significantly decreased in children with ADHD compared to controls, numerous clinical studies have examined the effects of omega-3 PUFA supplementation on ADHD symptoms. A systematic review of meta-analyses of double-blind placebo-controlled trials, in which ADHD symptoms were rated by parents and teachers, concluded that the effect sizes for PUFA supplementation were small (19). The pooling of the negative results of a more recent study with previous findings showed no overall effect of omega-3 PUFAs on…”

“…The role of food hypersensitivities in ADHD is a promising avenue worthy of further exploration. A systematic review of metaanalyses of double-blind placebo-controlled trials found no convincing evidence of therapeutic efficacy of artificial food color elimination, while the few-foods diet, which excludes many foods and additives, may offer new treatment options (19). The hypothesis of a relationship between food hypersensitivity and ADHD is supported by several studies (44)(45)(46)(47)(48).…”