EVIDENCE-BASED ANSWER
PROBABLY NOT, based on available data. Insufficient evidence exists to suggest that dietary interventions improve the symptoms of attention deficit hyperactivity disorder (ADHD) in children (strength of recommendation: B, extrapolation from randomized controlled trials [RCTs]). Interventions that have been investigated include removal of sugar and artificial food colorings from the diet and supplementation with fatty acids.
Evidence summary
ADHD affects 7% to 8% of school-age children, and the prevalence is increasing.1 The quality of studies investigating the link between diet and ADHD is limited by small sample sizes, subjective outcome measures, and nonstandardized intervention protocols.
Elimination diets show little or no effect
Studies of elimination diets for ADHD have investigated the effects of withholding sugar and artificial food colorings (AFCs).
Sugar. A 1995 meta-analysis of 16 double-blind, randomized, placebo-controlled trials evaluated the effect of dietary sugar in the form of sucrose, glucose, and fructose on behavior or cognition of children. Outcomes included subjective measurements from teachers, parents, and researchers, as well as objective scoring of activities.
No significant differences in the summary effect size were noted for any measured variable. A weakness of the analysis was that not all of the trials studied children who had been specifically diagnosed with ADHD.2
AFCs. A 2004 meta-analysis of 15 double-blind, placebo-controlled trials (total 219 children) evaluated the effect of AFCs on hyperactivity. Outcomes were measured by behavioral rating scales that ranged from standardized forms such as the Conners Parent-Teacher Questionnaire (12 trials) to nonvalidated author-developed scales (3 trials). Analysis revealed a small summary effect size (0.283; 95% confidence interval, 0.079-0.488), and the authors concluded that AFCs do have a small effect on hyperactivity.3
A secondary analysis of children who previously showed worsening of hyperactivity with AFCs (either by parental report or in an earlier study) found a larger effect size (0.53). This finding implies that a subset of children whose parents notice an increase in hyperactivity with AFCs may benefit from exclusion. However, because the quality of the meta-analysis is limited by the heterogeneity of the studies, publication bias, unvalidated outcome measures, and variety of diagnoses in the participants, no recommendation can be made for AFC exclusion diets.3