LAUSR

Abstract BACKGROUND The gut microbiota (GM) plays an important role in human health and is being investigated as a possible target for new therapies. Although there are many studies showing that emodin can improve host health, emodin–GM studies are scarce. Here, the effects of emodin on the GM were investigated in vitro and in vivo. RESULTS In vitro single bacteria cultivation showed that emodin stimulated the growth of beneficial bacteria Akkermansia, Clostridium, Roseburia, and Ruminococcus but inhibited major gut enterotypes (Bacteroides and Prevotella). Microbial community analysis from a synthetic gut microbiome model through co‐culture indicated the consistent GM change by emodin. Interestingly, emodin stimulated Clostridium and Ruminococcus (which are related to Roseburia and Faecalibacterium) in a mice experiment and induced anti‐inflammatory immune cells, which may correlate with its impact on specific gut bacteria. CONCLUSION Emodin (i) showed similar GM changes in monoculture, co‐culture, and in an in vivo mice experiment and (ii) simulated regulatory T‐cell immune responses in vivo. This suggest that emodin may be used to modulate the GM and improve health. © 2022 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.