The potential influence of fruit polyphenols on colonic microflora and human gut health

Abstract

The effect of commondietary polyphenols on growth of human gut bacteria and their adhesion to enterocyteswas investigated. The influence on the growth of a probiotic (Lactobacillus rhamnosus), a commensal (Escherichia coli) and two pathogenic bacteria (Staphylococcus aureus, Salmonella typhimurium) was determined, together with effects on adhesion of pathogenic and probiotic bacteria to cultured Caco-2 cells. All polyphenols, except rutin, were found to affect the viability of representative gut flora in vitro, at doses likely to be present in the gastrointestinal tract, but to differing degrees. Naringenin and quercetin were the most active with the lowest minimum inhibitory concentrations for all the four bacteria tested. The remaining polyphenols had the most marked effect on the Grampositive enteropathogen S. aureus. Naringenin and phloridzinwere themost effective inhibitors of S. typhimuriumadherence to Caco-2 enterocyteswhile phloridzin and rutin enhanced the adherence of the probiotic L. rhamnosus. Polyphenols appear to have potential to alter gutmicroecology and, by affecting the total number of beneficial microflora in the gut, may confer positive gut health benefits.