A systematic review of the effect of dietary exposure that could be achieved through normal dietary intake on learning and performance of school-aged children of relevance to UK schools.

Systematic review of studies in developed countries assessing whether diet or dietary change affects learning, educational performance, and behavior in school-aged children aged 4 to 18 years. The evidence base included 15 breakfast studies, 6 sugar-exposure studies, 5 fish oil trials, 2 vitamin/mineral studies, and 1 supplemented-diet study; most participants were healthy mainstream schoolchildren, with some studies in children with ADHD or differing socioeconomic backgrounds.

This review covered several dietary interventions relevant to school performance, but the supplement-focused regimens were mainly omega-3 formulations and low-dose multivitamin/mineral products. Fish oil regimens varied across studies, including 345 mg DHA/day; 480 mg DHA, 80 mg EPA, 96 mg GLA and 40 mg AA per day; 558 mg EPA, 174 mg DHA and 60 mg GLA per day; 186 mg EPA, 480 mg DHA, 96 mg GLA and 42 mg AA per day; and DHA at 514 mg/day or 3.6 g/week. Two studies evaluated low-dose multivitamin and mineral supplementation.

Overall, evidence was insufficient and inconsistent to show that dietary exposure or supplementation reliably improves learning, educational performance, or behavior in school-aged children. The clearest signal was for some EPA/DHA-rich fish oil formulations, where small benefits were reported in certain studies and the effect appeared to depend on dose and duration. Low-dose multivitamin/mineral evidence was mixed: one US trial reported a modest non-verbal IQ increase (P=0.038), while a British adolescent study found no significant effect. The single very small Mexican study of a supplemented 'good food' diet suggested better examination results and behavior, but the evidence base was too limited and methodologically weak for firm conclusions.

The included studies were highly heterogeneous in intervention type, duration, and outcome measures, with many short-term trials and limited use of universal validated educational attainment tools. Sample sizes were often small, power calculations were uncommon, and several findings came from single studies or subgroups, limiting confidence and generalizability. UK-representative long-term data were sparse, and reporting of habitual diet, physical activity, and broader family/community context was limited.