Aged oolong tea alleviates dextran sulfate sodium-induced colitis in mice by modulating the gut microbiota and its metabolites

•The prebiotic effect of AOT at four storage periods on gut microbiota was revealed.•AOT alleviated inflammation-related damage in DSS-induced colitis mice.•The colitis-relieving effect of AOT was related to the change in gut microbiota.•AOT ameliorated metabolic disorders in DSS-induced colitis mice.•AOT is a potentially reliable strategy for the prevention of colitis.