Natural polysaccharides exhibit anti-tumor activity by targeting gut microbiota.

Natural polysaccharides, the abundant dietary components, show potent antitumor bioactivity in treatment and chemoprevention. Compared with traditional tumor therapy, natural polysaccharides are characterized by the low toxicity and immuno-regulation function. Recent researches have indicated that the anti-tumor of polysaccharides was partly attributable to modification in the composition of gut microbiota when polysaccharides were digested. Indeed, microbial dysbiosis or alteration of certain bacterial species has been reported in tumorigenesis. Natural polysaccharides intake can reverse such changes by enriching health-promoting bacteria and metabolite the intestine. In this review, we first summarize current knowledge on the anti-tumor activity of polysaccharides, and demonstrate the relationship between bacteria and metabolite in the intestine tumorigenesis and microbial dysbiosis. Thereafter, and the "polysaccharides-gut microbiota" is put forward for polysaccharides to exhibit their antitumor activity, which may attribute to the improved leaky gut, avoided hypernutrition, and reinforced immune homeostasis, finally creating a systemic environment to lower the risks of tumor.