Proper nutrition is crucial for normal brain and neurocognitive development. Failure to optimize neurodevelopment early in life can have profound long-term implications for both mental health and quality of life. Although the first 1000 days of life represent the most critical period of neurodevelopment, the central and peripheral nervous systems continue to develop and change throughout life. All this time, development and functioning depend on many factors, including adequate nutrition. In this review, we outline the role of nutrients in cognitive, emotional, and neural development in infants and young children with special attention to the emerging roles of polar lipids and high quality (available) protein. Furthermore, we discuss the dynamic nature of the gut-brain axis and the importance of microbial diversity in relation to a variety of outcomes, including brain maturation/function and behavior are discussed. Finally, the promising therapeutic potential of psychobiotics to modify gut microbial ecology in order to improve mental well-being is presented. Here, we show that the individual contribution of nutrients, their interaction with other micro- and macronutrients and the way in which they are organized in the food matrix are of crucial importance for normal neurocognitive development.

The human gut microbiome influence on brain function and mental health is an emerging area of intensive research. Animal and human research indicates adolescence as a sensitive period when the gut-brain axis is fine-tuned, where dietary interventions to change the microbiome may have long-lasting consequences for mental health. This study reports a systematic review and meta-analysis of microbiota-targeted (psychobiotics) interventions on anxiety in youth, with discussion of a consultation on the acceptability of psychobiotic interventions for mental health management amongst youth with lived experience. Six databases were searched for controlled trials in human samples (age range: 10–24 years) seeking to reduce anxiety. Post intervention outcomes were extracted as standard mean differences (SMDs) and pooled based on a random-effects model. 5416 studies were identified: 14 eligible for systematic review and 10 eligible for meta-analysis (total of 324 experimental and 293 control subjects). The meta-analysis found heterogeneity I² was 12% and the pooled SMD was −0.03 (95% CI: −0.21, 0.14), indicating an absence of effect. One study presented with low bias risk, 5 with high, and 4 with uncertain risk. Accounting for risk, sensitivities analysis revealed a SMD of −0.16 (95% CI: −0.38, 0.07), indicative of minimal efficacy of psychobiotics for anxiety treatment in humans. There is currently limited evidence for use of psychobiotics to treat anxiety in youth. However, future progress will require a multidisciplinary research approach, which gives priority to specifying mechanisms in the human models, providing causal understanding, and addressing the wider context, and would be welcomed by anxious youths.

This systematic review brings together human psychobiotic interventions in children and adolescents (aged 6–25 years) to evaluate the efficacy of pre- and probiotic supplements on stress, anxiety, and cognitive outcomes. Psychobiotic interventions in animal studies highlighted sensitivity to effects during development and maturation in multiple domains from emotion to cognitive processing. Several translational psychobiotic interventions in humans have been carried out to assess effects on emotion and cognition during childhood and into adulthood. The findings illustrate that there are limited consistent psychobiotic effects in developing human populations, and this is proposed to be due to heterogeneity in the trials conducted. Consequentially, it is recommended that three specific factors are considered in future psychobiotic trials: (1) Specificity of population studied (e.g., patients, developmental age), (2) specificity of intervention, and (3) homogeneity in outcome measures.

BACKGROUND Dietary intake plays a crucial role in health research, yet existing methods for its measurement present several challenges such as participant burden, lengthy recording processes and human errors, and do not account for age-specific variations. OBJECTIVE This study assessed the relative validity of a food recording program within Libro, a real time diet tracking app, compared to a 24-hour recall method, specifically Intake24, among a group of young people sampled from a population vulnerable to eating misbehaviour. The food recording program was customized for the target population based on feedback gathered from a focus group. METHODS The relative validity of Libro was tested by adopting a cross-over design which recorded food intake over a period of 3 non-consecutive weekdays and 1 weekend day with both methods. The primary outcome was concordance of total energy intake between the two methods, with secondary outcomes focusing on intake of protein, carbohydrates, fats, free sugars, fibre, and trans-fatty acids. Test-retest validity was assessed per each method with the intraclass correlation coefficient; a Bland-Altman plot and t-test were performed to test agreement at group level; correlation coefficient and cross-classification were performed to assess agreement at individual level. RESULTS The average intraclass correlation coefficient for energy intake measured by Libro over four days was 0.85 (95% CI: 0.76-0.91). Compared to Intake24, average energy intake recorded using Libro was significantly lower (mean difference: -554 Kcal, 95% CI: -804.1 to -305.6 Kcal, p < 0.001), potentially driven by the reduced reporting of foods rich in free sugars. The correlation coefficient for average energy intake measured by Libro vs Intake24 was 0.32 (p = 0.03), with only 27.7 % of subjects classified in the same quartile with both methods (κ = 0.31, p = 0.03). Concordance varied across specific dietary component measures. CONCLUSIONS While Libro had good test-retest reliability if adopting a multi recall method, it underreported energy and other aspects of dietary intake, along with poor classification performance compared to Intake24. These results might be partially explained by the absence of pop-up memory prompts (which are a feature of Intake24), and the inability to customise the notification system throughout the day. We also suggest that a user-centred interface, graphic design, and implementation of strategies to enhance motivation may play a role in affecting participants compliance and should be improved to enhance the overall food recording process.

Background Emerging evidence highlights the gut-brain axis as a key pathway linking diet and anxiety, yet the key determinants remain unclear. Most studies have focused on single components of diet and rarely integrate long- and short-term intake. Furthermore, prior gut-brain work has focused on microbiome composition, while functional features remain underexplored. In this study, we investigated associations between long- and short-term dietary intake, gut microbiome composition and functions, and anxiety in a subclinical cohort of 46 females (18-24 years) from the United Kingdom. Results Long-term diet quality was assessed using the Healthy Eating Index (HEI-2020) derived from a food frequency questionnaire, stratifying participants into lower and higher diet quality clusters. Short-term dietary intake was assessed via 24-hour recalls. Shotgun metagenomics of stool samples was used to assess differences in alpha and beta diversity indices, species abundances, and bacterial pathways putatively metabolizing gut-brain-axis-relevant molecules. Anxiety was measured using the State-Trait Anxiety Inventory (state subscale STAI-s). Regression models identified diet quality (HEI cluster) as the primary dietary feature of anxiety variation. The presence of Ruminococcus gnavus and Flavonifractor plautii and the abundances of Bilophila wadsworthia and Bacteroides thetaiotaomicron were positively associated with anxiety. The presence of Feacalibacterium prausnitzii and greater abundances of butyrate, propionate, and GABA synthesis pathways were inversely associated with anxiety. Non-linear models revealed a U-shaped relationship between inositol synthesis and STAI-s. Finally, we found that habitual diet quality may modulate anxiety-related responses to short-term dietary variation. Conclusions These findings reveal widespread links between long-term diet quality, microbiota composition and function, and anxiety symptoms. These results point towards several promising targets for prebiotic, probiotic, postbiotic, and dietary interventions aimed at reducing anxiety.