Probiotics and Their Role in Modulating the Human Microbiome: Mechanisms, Health Effects, and Emerging Perspectives; A Review Article

Abstract

  The human microbiome consists of a complex community of microorganisms that plays an essential role in maintaining host balance, immune function, metabolic processes, intestinal integrity, and protection against pathogens. Disruption of this microbial community (dysbiosis) has been associated with various gastrointestinal and systemic diseases. Probiotics are live microorganisms that, when taken in adequate amounts, offer health benefits to the host. It is becoming increasingly evident that probiotics are able to interact with the resident microbiome and have an impact on the microbial composition, metabolism, intestinal barrier, and immune response and host–microbe interactions. But probiotic activity is strain specific and can be different depending on the host's normal microbiome, diet, age, health and environment. However, recent studies have highlighted that probiotics do not necessarily permanently colonize the gastrointestinal tract, but rather that many probiotic strains have transient and personal effects. Pathogens are competitively excluded, antimicrobial compounds are produced, short-chain fatty acid metabolism is modulated, epithelial tight junctions are regulated, bile acid metabolism is altered, immune signaling is modulated, and resident microbial communities are interacted with. Probiotics have been investigated for a variety of conditions, including metabolic disorders, inflammatory bowel diseases, irritable bowel syndrome, gastrointestinal problems, and diarrhea linked to antibiotics.  However, lack of clinical consistency underscores the need for strain specific characterization, individualization and consistency in microbiome analysis and carefully designed clinical trials. The present review compiles the current knowledge about probiotics, the human microbiome, the mechanisms of probiotic–microbiome interactions, the potential health benefits of probiotics, its limitations, safety concerns, and new trends in the development of precision probiotics, synbiotics, postbiotics, and personalized microbiome-based approaches.