Diet and the Developing Brain: A Systematic Review of Nutritional Influences on Adolescent Cognitive and Academic Outcomes

Adolescence is a critical period of neurodevelopment, yet the role of nutrition in shaping cognitive and academic outcomes during this stage remains underexplored. This systematic review synthesizes evidence from 48 controlled trials and 25 prospective studies examining how diet influences cognitive performance and educational attainment between ages 8 and 19. Four databases (PsycINFO, Scopus, PubMed, Web of Science) were searched up to February 2026. Studies were synthesized by design, with risk of bias assessed using Cochrane and Joanna Briggs Institute tools. Prospective studies beginning in infancy-typically of higher methodological quality-suggest that unhealthy diets in the first 3 y of life may have lasting adverse effects on intelligence in adolescence. Controlled trials of dietary interventions during adolescence point to potential benefits for cognitive and academic outcomes, though findings vary and are often constrained by methodological limitations. To advance research in this field, we propose 7 guiding principles, including adopting a life course perspective, moving beyond nutrient isolation, using biologically valid biomarkers, incorporating puberty and sex-specific analyses, standardizing outcome measures, prioritizing context and population characteristics, and controlling for key confounders. These principles aim to strengthen the design, relevance, and impact of future studies in adolescent nutrition and brain health. This study was preregistered on PROSPERO as CRD42023413970.