Research Nut: Walnuts

Pinar-Martí, A., N. Ayala-Aldana, M. Ruiz-Rivera, N. Lertxundi, M. Subiza-Pérez, L. González-Safont, J. Vioque, I. Riaño-Galán, C. Rodríguez-Dehli, L. Iglesias-Vázquez, V. Arija, S. Fernández-Barrés, D. Romaguera, V. Pascual-Rubio, A. Fabregat-Sanjuan, D. Healy, X. Basagaña, M. Vrijheid, M. Guxens, M. Foraster, J. Julvez, 2025. Maternal prenatal nut and seafood consumption and child neuropsychological function from 4 to 15 years of age: a population-based cohort study. Am J Clin Nutr. S0002-9165(25)00249-7. doi: 10.1016/j.ajcnut.2025.04.032.

Background. Understanding the role of maternal diet in early brain development is critical, as pregnancy represents a period of significant vulnerability and growth for the developing brain. Objectives. This study aims to assess the association between maternal nuts, total seafood, and large fatty fish consumption during pregnancy and offspring neuropsychological function ≤15 y, considering the potential mediation of omega-3 fatty acids. Methods. This study was part of The Spanish Childhood and Environment birth cohort, following 1737 mother–child pairs from pregnancy to age 15. Maternal diet was evaluated using a semiquantitative food frequency questionnaire, whereas children’s neuropsychological function was measured through standardized computer-based tests. Attention (hit reaction time and its variability, HRT and HRT-SE) was measured with the Conners’ Kiddie Continuous Performance Test and the Attention Network Test. Working memory (detectability in 2-back, d2′, and 3-back tasks, d3′) was evaluated using the N-back task. Fluid intelligence was assessed with Raven’s Progressive Matrices and the Test of Primary Mental Abilities. Linear mixed-effects regression models assessed the association of nuts, seafood and large fatty fish with neuropsychological outcomes, whereas generalized structural equation modeling was used for mediation analyses. Results. Higher maternal nut consumption was significantly linked to improved attention [HRT-SE β = –0.05, 95% confidence interval (CI): –0.09, –0.00] and working memory (d2′ β = 0.05, 95% CI: 0.00, 0.09, and d3′ β = 0.06, 95% CI: 0.02, 0.11) in offspring. Greater consumption of large fatty fish was associated with better attention (HRT-SE β = –0.06, 95% CI: –0.10, –0.02; and HRT β = –0.04, 95% CI: –0.08, –0.00), and fluid intelligence (β = 0.08, 95% CI: 0.02, 0.13). Omega-3 fatty acids mediated 8%–14% of these effects on attention. Conclusions. Maternal diet at pregnancy and omega-3 intake may support long-term cognitive development in children and adolescents.

Bell, L., G.F. Dodd, M. Jeavons, D.R. Fisher, A.R. Whyte, B. Shukitt-Hale, C.M. Williams, 2025. The impact of a walnut-rich breakfast on cognitive performance and brain activity throughout the day in healthy young adults: a crossover intervention trial. Food Funct. 16(5):1696-1707. https://doi.org/10.1039/d4fo04832f

A healthy diet is essential for optimal brain health and many bioactives from food are linked to cognitive benefits. To examine whether walnuts led to cognitive improvements throughout the day, 32 healthy young adults, aged 18-30, were tested in a double-blind, crossover pilot study, to compare the effects of a breakfast containing 50 g walnuts with a calorie-matched control containing no nuts. Cognition, mood, blood, and EEG measures were recorded at baseline and 2, 4, and 6 hours postprandially. Mood ratings for negative affect appeared worse following walnuts compared to control, possibly due to a general dislike of the intervention. However, walnuts elicited faster reaction times throughout the day on executive function tasks. Memory recall performance at 2 hours was worse for walnuts compared to control, but by 6 hours this finding was reversed with walnuts outperforming the control. EEG PSD analysis revealed differences in frontoparietal activity in the walnut condition compared to the control condition during memory recall and during executive function performance. These results may reflect between-treatment differences in cognitive effort or attentional processes while performing the tasks. Blood analysis revealed lower circulating non-esterified fatty acids and small increases in glucose availability following consumption of walnuts compared to control, suggesting enhanced glucose availability as one possible mechanism of action. Further investigations of other potential mechanisms are needed. Overall, these findings provide evidence for reaction time benefits throughout the day following a walnut-rich breakfast, while memory findings were mixed with benefits only observed later in the day. However, more research is needed into how diets containing walnuts might regulate cognitive improvements in humans postprandially and over the longer term.