Figure 2.

Overview of mechanisms of probiotics’ action. Probiotics exert their beneficial effects mainly by ensuring the proper balance of the microbiota colonizing the gut. Probiotic activity depends on stabilization of the epithelial barrier, induction of mucin secretion, and aggregation skills. By adhering to enterocytes, they reduce the opportunity for the colonization of this ecological niche by pathogenic bacteria. They also produce various, not always fully characterized, metabolites that inhibit the growth of pathogens. Additionally, they modulate the host immune system. Probiotics influence the gut through one or a combination of these mechanisms. Dotted arrow underlines the interplay between the host microbiota and probiotic strains and nature of these interactions can be both – positive, negative, depending on the composition of resident gut microbiota and used probiotic. DC, dendritic cells.