Summary: A new study has synthesized decades of research to evaluate how dietary patterns shape cognitive performance and academic outcomes in youth aged 8 to 19. Aggregating data from 73 studies, comprising 48 controlled trials and 25 prospective cohorts, investigators demonstrated that nutritional deficits during the first years of life, particularly infancy, carry long-term consequences that lower intelligence scores years later in adolescence.
The findings highlight that while early childhood establishes the baseline foundations of cognitive health, further high-quality research is required to determine if the structural and functional changes of adolescence offer a true secondary window for nutritional intervention.
Key Facts
- The 73-Study Dataset Audit: Supported by the IAFNS Cognitive Health Committee, the exhaustive review cross-references data from 48 controlled trials and 25 prospective longitudinal studies tracking youth between the ages of 8 and 19.
- The Infancy Baseline Deficit: Longitudinal analysis revealed a persistent link between poor dietary patterns during infancy and lower intelligence metrics years later in adolescence, a deficit that remains statistically significant even after controlling for external confounding variables.
- The Adolescent Ambiguity Window: Lead author Professor Hayley Young notes that while infancy establishes core cognitive foundations, data regarding dietary interventions during adolescence remains mixed and unsettled.
- The Pubertal Plasticity Core: Following early childhood, adolescence represents the next major phase of neuroplasticity, marked by widespread functional and structural brain remodeling driven by pubertal hormonal and endocrine shifts.
- Broad Nutritional Screening: The research team reviewed long-term evidence across a diverse spectrum of dietary variables, including iron, iodine, choline, vitamin D, polyphenols, fatty acids, grains, and broad multi-nutrient combinations.
- Contextual Variables Drive Outcomes: The authors state that apparent inconsistencies in nutrition literature do not mean diet lacks influence; rather, a nutrient’s impact depends heavily on developmental timing, population demographics, intervention duration, and the specific cognitive domain being measured.
- The Seven Research Principles: To standardize future nutritional neuroscience and establish whether adolescence serves as a viable window for brain optimization, the Swansea University team proposed seven guiding research principles.
Source: Swansea University
Published in Advances in Nutrition, the study brings together findings from 73 studies — including 48 controlled trials and 25 prospective studies — to examine how diet affects cognitive performance and academic outcomes in young people aged 8 to 19.
Supported by the IAFNS Cognitive Health Committee, the review found that unhealthy dietary patterns in the early years of life, particularly in infancy, may have lasting consequences for intelligence in adolescence.
Professor Hayley Young, from Swansea University’s School of Psychology and lead author of the study, said: “What stands out most clearly is that the foundations of cognitive health appear to be laid very early. A poorer diet in the first years of life was linked to lower intelligence years later, in adolescence, even after accounting for many other influences.
“The picture during adolescence itself is more mixed: some interventions show promise, but the evidence is far from settled. That is exactly why we need better-designed studies, so we can establish whether adolescence is a genuine second window of opportunity to support the developing brain through nutrition, rather than assuming it is.”
After infancy, adolescence represents a second key period of neuroplasticity, marked by widespread structural and functional changes driven in part by hormonal and endocrine shifts during puberty.
To reflect how brain development unfolds over time, the review draws on longitudinal studies exploring links between early-life diet and later cognitive and academic performance. This life-course approach recognises that later abilities build on earlier developmental milestones, allowing the team to examine how early nutrition may shape outcomes years later.
The researchers assessed long-term evidence on a wide range of nutrients and dietary components, including iron, iodine, choline, vitamin D, polyphenols, fatty acids, grains and multi-nutrient interventions.
Although findings across the literature can appear inconsistent, the authors caution against interpreting this as evidence that diet has little influence. Instead, they argue that the impact of nutrition depends on several factors — including the timing of dietary exposure during development, the characteristics of the population studied, the duration and type of intervention, and the particular cognitive abilities being measured.
To advance research in this emerging field, the team proposes seven guiding principles for future studies:
- Adopt a life-course perspective
- Move beyond nutrient isolation
- Use biologically valid biomarkers
- Include puberty and sex-specific analyses
- Standardise outcome measures
- Prioritise context and population characteristics
- Control for key confounders.
The authors conclude that further high‑quality research is needed to determine whether adolescence represents a unique window of opportunity to support cognitive development through nutritional interventions.
Key Questions Answered:
A: The current evidence is far from settled. The systematic review proved that a poor diet during the first years of life is linked to lower intelligence scores in adolescence. While adolescence is a major phase of brain rewiring, more research is needed to prove if it can act as a second chance to reverse early childhood deficits.
A: Because a nutrient’s success depends on highly variable conditions, including the exact timing of the diet during development, the duration of the trial, who is being studied, and which specific cognitive skill is being measured. Inconsistencies reflect flawed study designs rather than a lack of dietary influence.
A: Because adolescence triggers widespread structural and functional brain changes driven by intense hormonal and endocrine shifts. Without accounting for these sex-specific biological changes, researchers cannot accurately measure how nutrients interact with the actively remodeling teenage brain.
Editorial Notes:
- This article was edited by a Neuroscience News editor.
- Journal paper reviewed in full.
- Additional context added by our staff.
About this diet and intelligence research news
Author: Ffion White
Source: Swansea University
Contact: Ffion White – Swansea University
Image: The image is credited to 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 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.
