Fig. 2

Strategies applied for modulating gut microbiota in CRC and the mechanisms of action of each strategy. Probiotics: Probiotics exert their effects on gut microbiota composition through immunomodulation, inhibition of pathogenic bacteria colonization, and enhancement of the gut barrier functions. Prebiotics: They act as gut microbiota modulatory elements through direct uptake by the intestine and exerting anti-inflammatory activities, prevention of the colonization of pathogens by interacting with them, fermentation by intestinal microbiota, and stimulation of beneficial gut bacteria. Postbiotics: They exert their tumoricidal functions through selective inhibiting tumor cells and protecting intestinal epithelium by inhibiting apoptosis in epithelial cells and increasing IgA secretion. Antibiotics: Antibiotics could deplete the intestine from harmful bacteria and preserve intestinal epithelium. FMT: This strategy helps restore the diversity of microbiota in the gut