The interconnection between dietary fibre, gut microbiome and psychological well-being

This review highlights the importance of dietary fibres (DF) intake and its interconnection with the gut microbiome and psychological well-being, while also exploring the effects of existing DF interventions on these aspects in adults. The gut microbiota is a complex and diverse ecosystem in which microbial species interact, influencing the human host. DF are heterogeneous, requiring different microbial species to degrade the complex DF structures. Emerging evidence suggests that microbial fermentation of DF produces short-chain fatty acids (SCFA), which may play a role in regulating psychological well-being by affecting neurotransmitter levels, including serotonin. The effectiveness of DF interventions depends on factors such as baseline gut microbiota composition, the dosage and the source of DF consumed. Although the gut microbiota of adults is relatively stable, studies have shown that the abundance of the species in the gut microbiota can change within 24 h of an intervention and may return to baseline following the termination of DF intervention. This review underscores the need for larger and well-powered dietary clinical trials incorporating longitudinal biological sample collections, advanced sequencing and omic techniques (including novel dietary biomarkers and microbial metabolites), validated subjective questionnaires and dietary records. Furthermore, mechanistic studies driven by clinical observations are crucial to understanding gut microbiota function and its underlying biological pathways, informing targeted dietary interventions.