Effect of walnut consumption on neuropsychological development in healthy adolescents: A multi-school randomised controlled trial

Essential for cognitive function are omega-3 fatty acids. It is becoming more well-accepted that adolescence plays a crucial role in brain susceptibility to nutritional influence. However, it is unknown if walnuts, an omega-3 alpha-linolenic acid (ALA) source, may help with teenage neurodevelopment. To determine if eating walnuts has positive impacts on the cognitive and behavioral development of teenagers, Pinar-Martí et al. (2023) undertook a 6-month multi-school randomized controlled nutrition intervention experiment, recruiting 771 healthy adolescents 11-16 years old who were randomly assigned to either an intervention or control group. The intervention group was given 30 g/day of raw walnut kernels to add to their diet for six months. At baseline and during the intervention, many major outcomes relating to neuropsychological (working memory, executive function, attention, and fluid intelligence) and behavioral (socio-emotional and attention deficit hyperactivity disorder [ADHD] symptoms) development were evaluated. As a gauge of compliance, the red blood cell (RBC) ALA level was assessed at baseline and after six months. Analysis of the results revealed that, for all major outcomes, there were no statistically significant differences in the intervention group compared to controls at six months in intention-to-treat analyses. Only the intervention group’s RBC ALA (%) substantially increased. The per-protocol (adherence-adjusted) effect on improvement in attention score (hit reaction time variability) was 11.26 ms for the intervention group in comparison to the control group, with an improvement in fluid intelligence score by 1.78 and a reduction in ADHD symptom score at 2.18. Thus, the authors demonstrated that healthy teenagers’ neurophysiological functions did not improve after being advised to eat walnuts for six months. However, those who adhered better to the walnut intervention showed improvements in sustained attention, fluid intelligence, and ADHD symptoms. The authors comment that their study lays the groundwork for future clinical and epidemiological studies on the impact of walnuts and ALA on adolescent neurodevelopment. [NPID: Adolescent health, cognitive function, neuropsychology, randomized nutritional intervention, public health, walnut intake]

Year: 2023

Reference: Pinar-Martí, A., Gignac, F., Fernández-Barrés, S., Romaguera, D., Sala-Vila, A., Lázaro, I., Ranzani, O. T., Persavento, C., Delgado, A., Carol, A., Torrent, J., Gonzalez, J., Roso, E., Barrera-Gómez, J., López-Vicente, M., Boucher, O., Nieuwenhuijsen, M., Turner, M. C., Burgaleta, M., Canals, J., … Julvez, J. (2023). Effect of walnut consumption on neuropsychological development in healthy adolescents: a multi-school randomised controlled trial. EClinicalMedicine, 59, 101954. https://doi.org/10.1016/j.eclinm.2023.101954