Microbial modulation of tryptophan metabolism links gut microbiota to disease and its treatment

Emerging studies have demonstrated that tryptophan (Trp) metabolism plays a critical role in maintaining intestinal and systemic homeostasis. Trp metabolism is involved in diseases such as metabolic syndrome, gastrointestinal cancers, neurological disorders, and viral diseases. The gut microbiota is crucial for regulating Trp metabolism, thereby influencing host health. Conversely, Trp metabolism can also modulate the composition and function of the gut microbiota. In this review, we summarize the mechanisms through which gut microbiota-regulated Trp metabolism contributes to disease development. We also discuss how external factors, such as antibiotics and diet, influence Trp metabolism and may offer protective effects against disease, including Covid-19. These advances have facilitated the development of novel therapeutic strategies targeting Trp metabolic dysfunction.