Meta-analysis of controlled trials shows sugar does not affect behavior or cognitive performance in children.
A comprehensive meta-analysis of 23 controlled studies found no evidence that sugar affects children's behavior or cognitive performance. While some observational studies suggest associations between sugar-sweetened beverages and ADHD symptoms, controlled trials using placebo comparisons consistently show no hyperactivity effects from sugar consumption.
Caveats
While controlled trials show no direct hyperactivity effect, some observational studies suggest broader associations between high-sugar diets and attention problems, possibly due to overall dietary patterns rather than sugar itself.