A randomised controlled trial into the effects of food on ADHD.
Level 2 - randomized trial
Individual randomized controlled trial
PubMed 18431534 · doi:10.1007/s00787-008-0695-7
What was done
Twenty-seven children (mean age 6.2 years) meeting DSM-IV criteria for ADHD were randomly assigned to either a 9-week restricted elimination diet intervention (15 children) or a waiting-list control group (12 children). The primary endpoint was clinical response, defined as a 50% or greater decrease in symptom scores at week 9 based on parent and teacher ratings on the abbreviated ten-item Conners Scale and the ADHD-DSM-IV Rating Scale. Changes in comorbid oppositional defiant disorder symptoms were also evaluated.
What was found
Intention-to-treat analysis showed clinical response rates in the intervention group versus waiting-list controls of 73% (11/15) versus 0% (0/12) by parent ratings, and 70% (7/10) versus 0% (0/7) by teacher ratings. The number of ADHD criteria on the ADHD Rating Scale showed an effect size of 2.1 (Cohen's d) and a 69.4% scale reduction. Comorbid oppositional defiant disorder symptoms also decreased significantly more in the intervention group than in controls (Cohen's d 1.1, scale reduction 45.3%).
Why it matters
This trial suggests that dietary factors may substantially drive ADHD symptoms in some young children, indicating that a strictly supervised elimination diet can serve as a diagnostic and therapeutic tool.
Limits
The sample size was very small (n = 27), and several children lacked teacher ratings (5 in intervention, 5 in control). Using an unblinded waiting-list control rather than a blinded sham diet introduces high risk of parental expectation and reporting bias. The abstract reports no long-term follow-up, dietary compliance metrics, or identification of specific causative foods.
Cited by
- partial Two studies from the Netherlands found that putting children with ADHD on an elimination diet resulted in 70% losing their symptoms.