Summary: A comprehensive systematic review has pooled findings from 73 studies to assess how dietary patterns influence cognitive performance and academic outcomes in young people aged 8 to 19. Combining evidence from 48 controlled trials and 25 prospective cohort studies, researchers report that poor nutrition during the earliest years of life—particularly infancy—can produce lasting reductions in intelligence scores measured during adolescence.
While early childhood appears to set the foundational trajectory for cognitive health, the authors emphasize the need for higher-quality, developmentally informed research to determine whether adolescence represents a true second window of opportunity for nutrition-based interventions.
Key Facts
- The 73-study evidence base: The review, supported by the IAFNS Cognitive Health Committee, integrates 48 controlled intervention trials and 25 prospective longitudinal studies that follow children and adolescents between ages 8 and 19.
- Infancy establishes a baseline deficit: Long-term cohort data consistently link suboptimal diets in infancy with lower intelligence metrics in adolescence, even after accounting for socioeconomic and other confounding influences.
- Adolescence is an uncertain window: Controlled trials during adolescence show mixed results. Some interventions hint at cognitive or academic benefits, but the overall evidence remains inconclusive due to methodological variation.
- Pubertal plasticity matters: After early childhood, adolescence is the next major phase of brain plasticity, characterized by broad structural and functional remodeling driven by hormonal and endocrine changes.
- Wide range of nutrients reviewed: The investigators evaluated long-term studies covering iron, iodine, choline, vitamin D, polyphenols, fatty acids, whole grains and multi‑nutrient combinations.
- Context shapes outcomes: Inconsistencies across studies often reflect differences in developmental timing, population characteristics, intervention dose and duration, and which cognitive domains were assessed, rather than absence of nutritional effects.
- Seven principles to improve future work: To reduce ambiguity and strengthen causal inference in nutritional neuroscience, the authors propose seven guiding principles for future research.
Source: Swansea University
Published in Advances in Nutrition, this review brings together evidence from intervention trials and long-term cohort studies to examine how diet affects cognition and school performance across childhood and adolescence.
Professor Hayley Young of Swansea University’s School of Psychology, lead author of the paper, summarizes the core finding: early nutrition shapes later cognitive outcomes. She notes that children who experienced poorer diets in the first years of life showed lower intelligence scores in adolescence, a relationship that persisted after adjusting for many known confounders.
Professor Young adds that adolescence remains a complex and unsettled period for nutritional research. Although pubertal brain remodeling suggests a plausible biological opportunity for intervention, current trials are heterogeneous and often limited by short follow‑ups, small samples or narrow outcome measures. Well‑designed, life-course studies are needed to test whether targeted nutrition during adolescence can offset earlier deficits or enhance later cognitive capacities.
The review favors a life-course perspective: brain development is cumulative, so later abilities depend on earlier milestones. Longitudinal cohorts beginning in infancy allow investigators to observe how early dietary exposures map onto cognitive and academic performance years later, while intervention trials can test causality at different developmental stages.
Across the literature the team assessed nutrients and dietary patterns in context—considering population demographics, socioeconomic factors, duration and timing of exposure, and the specific cognitive domains measured. They caution that variability in these factors helps explain apparent contradictions between studies.
To guide future research and improve comparability, the authors recommend seven research principles:
- Adopt a life-course perspective that links early exposures to later outcomes.
- Move beyond isolating single nutrients to consider whole-diet patterns and nutrient interactions.
- Use biologically valid biomarkers to confirm nutrient exposure and physiological impact.
- Include puberty timing and sex-specific analyses to capture differential developmental trajectories.
- Standardize cognitive and academic outcome measures to improve comparability.
- Prioritize contextual and population characteristics to ensure relevance and generalizability.
- Control rigorously for key confounders such as socioeconomic status, parental education and early health factors.
The authors conclude that while infancy is a critical period for setting cognitive trajectories, robust, standardized research is required to determine whether adolescence constitutes a meaningful second opportunity for nutritional support of the developing brain.
Key Questions Answered
A: Current evidence does not resolve this question. Longitudinal data link early poor nutrition with lower adolescent intelligence, and although adolescence is a period of significant brain plasticity, more rigorous long-term trials are needed to determine whether later dietary improvements can fully reverse early deficits.
A: Differences in study design explain much of the variation: timing and duration of exposure, who is included in the study, which nutrients or dietary patterns are assessed, the cognitive domains measured, and how outcomes are defined and measured all influence results.
A: Puberty involves major hormonal and endocrine changes that drive sex-specific brain development. Without accounting for these processes, studies may miss important interactions between nutrition and the dynamically remodeling adolescent brain.
Editorial Notes
- This article was edited by a Neuroscience News editor.
- The journal paper was reviewed in full by the editorial team.
- Additional contextual information was added by staff to clarify implications for research and policy.
About this research
Author: Ffion White
Source: Swansea University
Contact: Ffion White – Swansea University
Image credit: Neuroscience News
Original research: “Diet and the Developing Brain: A Systematic Review of Nutritional Influences on Adolescent Cognitive and Academic Outcomes” by Hayley A. Young, Chantelle M. Gaylor, Anthony Brennan, Abigail McIntosh and Amy R. Griffiths. Advances in Nutrition. DOI: 10.1016/j.advnut.2026.100648. Closed access.
Abstract
Diet and the Developing Brain: A Systematic Review of Nutritional Influences on Adolescent Cognitive and Academic Outcomes
Adolescence is a key phase of neurodevelopment, but the role of nutrition in shaping cognitive function and school performance during this stage is not yet fully defined. This systematic review synthesizes evidence from 48 controlled trials and 25 prospective studies assessing diet-related effects on cognition and academic attainment between ages 8 and 19.
Four major databases were searched through February 2026, and studies were evaluated by design and methodological quality. Prospective cohorts that began in infancy—often better suited to disentangle developmental pathways—suggest that unhealthy diets in the first three years of life may exert lasting negative effects on intelligence measured in adolescence. Trials conducted during adolescence show potential benefits for cognition and academic outcomes in some cases, but heterogeneity in methods and measures limits firm conclusions.
To strengthen future work, the authors propose seven guiding principles—adopting a life-course perspective, moving beyond single-nutrient thinking, using valid biomarkers, incorporating puberty and sex-specific analysis, standardizing outcomes, prioritizing context and population characteristics, and controlling for confounders—to enhance the design, relevance and impact of research in adolescent nutrition and brain health.
This review was preregistered on PROSPERO (CRD42023413970).