Dietary and Supplementation Strategies for Modulating Gut Microbiota: A Narrative Review

The composition and balance of the gut microbiota are important for human health, as they are involved in metabolic processes, immune regulation, intestinal barrier function, and gut-brain communication. This narrative review summarizes current evidence on dietary and supplementation-based strategies for modulating the gut microbiota, with particular attention to dietary fiber, fermented foods, prebiotics, probiotics, synbiotics, and postbiotics. The review discusses their potential mechanisms of action, including effects on microbial composition, short-chain fatty acid production, intestinal barrier integrity, immune responses, and metabolic homeostasis. Particular emphasis is placed on the context-dependent nature of microbiota modulation, as the effects of dietary and supplementation strategies may vary according to baseline microbiota composition, health status, habitual diet, probiotic strain, dose, and intervention duration. Overall, current evidence suggests that microbiota-targeted nutritional strategies may support gut homeostasis and selected health-related outcomes; however, their effects are not universal and require more personalized and better-controlled approaches in future research.