Effect of walnut consumption on neuropsychological development in healthy adolescents: a multi-school randomised controlled trialResearch in context

• Published in: EClinicalMedicine 2023-05, Vol.59, p.101954
• Main Authors: Ariadna Pinar-Martí, Florence Gignac, Silvia Fernández-Barrés, Dora Romaguera, Aleix Sala-Vila, Iolanda Lázaro, Otavio T. Ranzani, Cecilia Persavento, Anna Delgado, Albert Carol, Jaume Torrent, Judith Gonzalez, Eduard Roso, Jose Barrera-Gómez, Mónica López-Vicente, Olivier Boucher, Mark Nieuwenhuijsen, Michelle C. Turner, Miguel Burgaleta, Josefina Canals, Victoria Arija, Xavier Basagaña, Emilio Ros, Jordi Salas-Salvadó, Jordi Sunyer, Jordi Julvez
• Format: Article
• Language: English
• Subjects: Adolescent health; Cognitive function; Neuropsychology; Public health; Randomised nutritional intervention; Walnut intake
• ISSN: 2589-5370; 2589-5370

Background: Omega-3 fatty acids are critical for neuropsychological functioning. Adolescence is increasingly believed to entail brain vulnerability to dietary intake. The potential benefit on adolescent neurodevelopment of consuming walnuts, a source of omega-3 alpha-linolenic acid (ALA), remains unclear. Methods: We conducted a 6-month multi-school-based randomised controlled nutrition intervention trial to assess whether walnut consumption has beneficial effects on the neuropsychological and behavioural development of adolescents. The study took place between 04/01/2016 and 06/30/2017 in twelve different high schools in Barcelona, Spain (ClinicalTrials.gov Identifier: NCT02590848). A total of 771 healthy teenagers aged 11–16 years were randomised into two equal groups (intervention or control). The intervention group received 30 g/day of raw walnut kernels to be incorporated into their diet for 6 months. Multiple primary endpoints concerning neuropsychological (working memory, attention, fluid intelligence, and executive function) and behavioural (socio-emotional and attention deficit hyperactivity disorder [ADHD] symptoms) development were assessed at baseline and after intervention. Red blood cell (RBC) ALA status was determined at baseline and 6 months as a measure of compliance. Main analyses were based on intention-to-treat using a linear mixed-effects model. A per-protocol effect of the intervention was analysed using inverse-probability weighting to account for post-randomisation prognostic factors (including adherence) using generalised estimating equations. Findings: In intention-to-treat analyses, at 6 months there were no statistically significant changes between the intervention and control groups for all primary endpoints. RBC ALA (%) significantly increased only in the intervention group, coefficient = 0.04 (95% Confidence Interval (CI) = 0.03, 0.06; p