The gut microbiota serves as a crucial mediator of host health, with its composition and function being profoundly shaped by dietary intake. Tryptophan (TRP), an essential amino acid, is metabolized by gut microorganisms into a diverse array of bioactive compounds that play pivotal roles in both physiological homeostasis and pathological processes. Consequently, dietary modulation of microbial TRP metabolism presents a promising avenue for precise nutritional interventions. This review explores the dual role of TRP metabolites in health and disease and systematically examines how various dietary bioactive ingredients regulate their microbial metabolism. We summarize current evidence on TRP-modulating dietary components, highlighting their health impacts and emerging applications in precision nutrition and microbiome-based therapies. Recent advances over the past decade reveal that dietary ingredients can directly or indirectly modulate gut health and related disorders by targeting TRP metabolic pathways. Key findings underscore the critical function of TRP metabolites in maintaining intestinal barrier integrity and their therapeutic potential in gut-related disorders. Furthermore, the emerging impact of food processing on TRP metabolism is discussed. Collectively, this evidence provides novel insights for future research and the strategic development of functional foods that harness the gut microbiota-TRP-metabolite axis. The article further discusses the optimisation of food processing techniques to enhance the in vivo bioavailability of indole derivatives and prebiotics. This provides a robust theoretical foundation and opens new avenues for future in-depth research in this field, ultimately aiming to facilitate the development of functional foods that target the gut microbiota-tryptophan-metabolite axis. Graphical abstract:Dietary nutrients directly modulate tryptophan metabolism or do so through food processing, thereby impacting intestinal health. • Identifies key gut microbes driving tryptophan metabolism and gut health. • Catalogues key gut microbial regulators of host tryptophan metabolism and their associated health impacts. • Proposes food processing to boost Trp bioavailability and beneficial metabolites for precision nutrition
Zhang et al. (Fri,) studied this question.