Analysis of the effects of Rosa roxburghii Tratt fruit polyphenols on immune function in mice through gut microbiota and metabolomics: An in vivo preclinical trial study

•Rosa roxburghii tratt polyphenols regulate cellular and non-specific immunity but have no significant effect on humoral immunity.•Rosa roxburghii tratt polyphenols regulate the differentiation balance of T cells.•Rosa roxburghii tratt polyphenols regulate the proportion of short-chain fatty acid producing bacteria,such as Blautia, Bacteroides, Lachnospiraceae_NK4A136_group, Roseburia.•Rosa roxburghii tratt polyphenols may affect T cells and macrophages through metabolites such as choline in plasma.