Objective: The purpose of this study is to investigate the impact of dietary fibre on the mental health and cognitive function of children and adolescents. Methods: All interventional and observational studies that contained information on the relevant population (children and adolescents), intervention/exposures (high dietary fibre consumption) and outcomes (mental and cognitive parameters) were eligible. Eight electronic databases (Embase, Medline, Pubmed, Web of Science, Scopus, PsycINFO, Cochrane Library and ClinicalTrials.gov) were searched up to December 11, 2023. Results: A total of 15 studies (n = 4628) met inclusion criteria, consisting of 9 intervention trials and 6 observational studies. According to observational studies, higher dietary fibre consumption was associated with a 49% reduction in the odds of depression compared to lower intake (P < 0.0001; OR = 0.51; 95% CI: 0.38, 0.69; I² = 0%). Furthermore, no significant correlations were found between dietary fibre consumption and intelligence or anxiety. Among intervention studies, no significant difference was observed between fibre supplementation and placebo in terms of anxiety (standardized mean difference (SMD): −0.23; 95% CI: −0.72, 0.27), stress (SMD: 0.03; 95% CI: −0.21, 0.28), memory (SMD: 0.46; 95% CI: −0.79, 1.71), or attention (SMD: −2.72; 95% CI: −6.30, 0.86). Conclusion: Evidence from observation studies demonstrated that higher dietary fibre consumption is associated with a decreased odds of depression symptoms, both in childhood and adolescence. However, the causal relationship between dietary fibre intake and mental and cognitive function in children and adolescents still requires further clarification through high-quality intervention studies in the future.

Given the worldwide epidemic of overweight and obesity among children, evidence-based dietary recommendations are fundamentally important for obesity prevention. Although the significance of the human gut microbiome in shaping the physiological effects of diet and obesity has been widely recognized, nutritional therapeutics for the mitigation of pediatric obesity globally are only just starting to leverage advancements in the nutritional microbiology field. In this review, we extracted data from PubMed, EMBASE, Scopus, Web of Science, Google Scholar, CNKI, Cochrane Library and Wiley online library that focuses on the characterization of gut microbiota (including bacteria, fungi, viruses, and archaea) in children with obesity. We further review host-microbe interactions as mechanisms mediating the physiological effects of dietary fibers and how fibers alter the gut microbiota in children with obesity. Contemporary nutritional recommendations for the prevention of pediatric obesity are also discussed from a gut microbiological perspective. Finally, we propose an experimental framework for integrating gut microbiota into nutritional interventions for children with obesity and provide recommendations for the design of future studies on precision nutrition for pediatric obesity.

Background/Objectives: Childhood metabolic dysregulation exerts a profound influence on the development of obesity and metabolic diseases. The human gut microbiota, with highly personalized characteristics, plays an important role in host metabolism. However, the dynamics of gut microbial features during this developmental phase are still unclear. This longitudinal observational study collected 204 fecal samples and 153 blood samples from 51 children (aged 8.90 ± 0.78 years) at four timepoints over 52 weeks, aiming to identify dynamic changes in individual gut microbiota and underlying mechanistic interactions that predict measures of pediatric metabolic health. Methods: Fecal samples were subjected to 16S rRNA gene amplicon sequencing and short-chain fatty acid quantification. Serum samples were analyzed for biochemical tests. Dietary intake, physical activity, clinical phenotypes, early-life factors, and fecal characteristics were further assessed. Results: In the results, the fecal microbiota dynamics exhibit inter-individual variation among children, allowing classification into high- and low-stability subgroups based on intra-individual β-diversity variability. Children with low-stability microbiota had adverse blood lipid profiles (p < 0.05). Compared to the high-stability group, the low-stability microbiota demonstrated significant association with low dietary fiber and highly variable amino acid consumption (|r| > 0.3, q < 0.05). Low-stability microbiota exhibited marked fluctuations in Phocaeicola vulgatus, which was strongly linked to both blood triglycerides and lipoprotein(a) levels, as well as dietary fiber and amino acid intake. Baseline depletion of P. vulgatus and Faecalibacterium duncaniae, combined with the children’s physiological status, lifestyle behaviors, and early-life factors, predicted microbial stability classification (AUROC = 0.93). Conclusions: These findings suggested that the variation in the gut microbiota dynamics could be considered as a possible complementary biomarker to understand the individualized responses within dietary interventions aimed at improving metabolic health in childhood. Further well-designed intervention study is needed to define these observational associations.