Impact of polyphenols from black tea and red wine/grape juice on a gut model microbiome

► We show the effects of polyphenols on a gut microbiome in vitro. ► In a gut model polyphenols are antimicrobial. ► Black tea polyphenols have differential effects from red wine/grape polyphenols. ► Polyphenol dosing changes the gut microbial community composition in a model. ► Most prominent changes are inhibition of Firmicutes and promotion of Proteobacteria.