Summary: A comprehensive systematic review has combined decades of research to evaluate how dietary patterns influence cognitive performance and academic outcomes in young people aged 8 to 19. Drawing on 73 studies—48 controlled trials and 25 prospective cohort studies—the authors found consistent evidence that poor nutrition during the first years of life, particularly in infancy, is associated with lower intelligence scores in adolescence. The review highlights early childhood as a foundational period for cognitive health while calling for stronger research to determine whether adolescence provides a genuine second window of nutritional opportunity for the developing brain.
The analysis emphasizes that the timing of nutritional exposure, the population studied, intervention duration and composition, and the cognitive domains measured are all critical to understanding how diet affects brain development. The research team proposes a life-course framework and seven guiding principles to improve future studies in nutritional neuroscience and adolescent brain health.
Key Facts
- Comprehensive 73-study review: The dataset combines 48 controlled trials and 25 prospective longitudinal studies examining diet and cognitive or academic outcomes from ages 8 to 19.
- Infancy establishes a baseline: Longitudinal evidence indicates that poor dietary patterns in infancy are linked to lower intelligence in adolescence, a relationship that persists after adjusting for many common confounders.
- Adolescence: an uncertain second window: While adolescence involves major brain remodeling, current intervention studies offer mixed results; stronger, better-designed trials are needed to test whether dietary change during puberty can reverse or reduce earlier deficits.
- Pubertal plasticity matters: Adolescence is characterized by widespread structural and functional brain changes driven by hormonal and endocrine shifts, making timing and sex-specific analysis crucial.
- Diverse nutritional factors reviewed: The review considered iron, iodine, choline, vitamin D, polyphenols, fatty acids, whole grains, and multi-nutrient approaches, among other dietary components.
- Context determines impact: Apparent inconsistencies across studies reflect differences in developmental timing, population context, intervention design, and outcome selection rather than an absence of dietary influence.
- Seven research principles proposed: The authors recommend standardized approaches to advance the field and to test whether adolescence is a viable life-course window for nutritional interventions.
Source: Swansea University
Published in Advances in Nutrition, this systematic review synthesizes findings from 73 studies—including 48 controlled trials and 25 prospective cohorts—to clarify how diet affects cognitive and academic outcomes in young people aged 8 to 19. Supported by the IAFNS Cognitive Health Committee, the review emphasizes long-term consequences of early-life nutrition and proposes a life-course research agenda for adolescent brain health.
Professor Hayley Young of Swansea University’s School of Psychology, lead author of the review, summarized the main takeaway: “The foundations of cognitive health are laid very early. A poorer diet during the first years of life was associated with lower intelligence years later, even after accounting for many other influences. Evidence from adolescence is more mixed—some interventions appear promising, but the data are not yet conclusive. That is why we need better-designed studies to test whether adolescence represents a second window of opportunity for nutritional support of the developing brain.”
The review adopts a life-course perspective, drawing on longitudinal studies that follow children from infancy into adolescence. This approach recognizes that later cognitive and educational outcomes build on earlier developmental milestones and that early nutritional exposures can have delayed effects on brain function and learning.
Researchers evaluated long-term evidence across a broad range of dietary variables and interventions. While some controlled trials conducted during adolescence suggest potential cognitive or academic benefits from dietary change, many studies suffer from methodological limitations—small sample sizes, short follow-up, inconsistent outcome measures, or limited biomarker data—that make definitive conclusions difficult.
To strengthen future research, the authors outline seven guiding principles for nutritional neuroscience studies focused on adolescents and young people:
- Adopt a life-course perspective to link early exposures with later outcomes.
- Move beyond single-nutrient approaches and consider whole-diet patterns and interactions.
- Use biologically valid biomarkers to confirm nutrient status and target mechanisms.
- Include puberty timing and sex-specific analyses to account for hormonal and developmental variability.
- Standardize cognitive and academic outcome measures to improve comparability across studies.
- Prioritize context and population characteristics to ensure findings are relevant and equitable.
- Control for key confounders—including socioeconomic factors, parental education, and early-life health—to isolate nutritional effects.
The authors conclude that while infancy appears to set important cognitive foundations, the question of whether adolescence is a distinct window for nutritional remediation remains open. High-quality, well-powered longitudinal trials and cohort studies that follow participants across developmental stages are essential to determine the potential for dietary interventions to support cognitive development during adolescence.
Key Questions Answered:
A: Current evidence does not support a definitive answer. Longitudinal studies show that poor nutrition in early life is linked to lower intelligence in adolescence. Although adolescence involves significant brain plasticity, more rigorous research is needed to determine whether dietary improvements during the teen years can fully reverse early deficits.
A: Differences in timing of exposure, study populations, intervention type and duration, and cognitive outcomes measured account for many apparent contradictions. Inconsistencies often reflect varied study design rather than a lack of dietary influence on cognition.
A: Puberty brings major hormonal, structural, and functional brain changes that differ by sex. Without accounting for these factors, studies risk overlooking how nutrients interact with a brain undergoing rapid, sex-specific remodeling.
Editorial Notes:
- This article was edited by a Neuroscience News editor.
- The journal paper was reviewed in full by the editorial team.
- Additional context was provided by staff to clarify implications for research and public health.
About this diet and intelligence research news
Author: Ffion White
Source: Swansea University
Contact: Ffion White – Swansea University
Image credit: Neuroscience News
Original Research: Closed access. “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
Abstract
Diet and the Developing Brain: A Systematic Review of Nutritional Influences on Adolescent Cognitive and Academic Outcomes
Adolescence is a critical period for brain development, but the role of nutrition during this stage is still underexplored. This systematic review synthesizes results from 48 controlled trials and 25 prospective studies investigating how diet affects cognitive performance and educational attainment between ages 8 and 19. Four databases were searched through February 2026, and studies were synthesized by design while assessing bias with Cochrane and Joanna Briggs Institute tools.
Prospective studies that began in infancy—often of higher methodological quality—suggest that unhealthy diets in the first three years of life may have lasting negative effects on intelligence in adolescence. Controlled trials conducted during adolescence offer some evidence of cognitive and academic benefits from dietary interventions, yet findings vary and are frequently limited by study design. To strengthen the evidence base, the review recommends seven guiding principles aimed at improving study design, measurement precision, and contextual relevance.
These recommendations are intended to guide future research that can better determine whether adolescence represents a meaningful opportunity to support cognitive development through targeted nutritional strategies. The study was preregistered on PROSPERO as CRD42023413970.