Dietary polyphenols are substrates for colonic microbiota. They and their metabolites
contribute to the maintenance of gastrointestinal health by interacting with epithelial
cells, and largely by modulating the gut microbial composition. Polyphenols may act
as promoting factors of growth, proliferation, or survival for beneficial gut bacteria—mainly
Lactobacillus strains—and thus, exerting prebiotic actions and inhibiting
the proliferation of some pathogenic bacteria such as Salmonella and Helicobacter
pylori species. To date the interactions affecting metabolic pathways and numerous
metabolites of dietary polyphenols have been widely documented. However, the effects
of dietary polyphenols on the modulation of the intestinal ecology and on the growth of
gut microbial species are still poorly understood. This paper summarizes data on the
influence of dietary polyphenols on gut microbiota and the main interactions between
dietary polyphenols and beneficial and pathogenic intestinal bacteria.