Fermented sea buckthorn compound juice inhibits colorectal cancer growth by regulating immunity and the gut microbiome

• Fermented sea buckthorn juice inhibited tumor growth in CT26 colon carcinoma cell line bearing mice. • Fermented sea buckthorn juice activated anti-tumor immunity and inhibited tumor-promoting responses in tumor-bearing mice. • Fermented sea buckthorn juice increased SCFAs in tumor-bearing mice and improved intestinal microbiota dysbiosis. The antitumor activity of a fermented juice (called Shaduojin, SDJ) made from sea buckthorn, raspberry, etc. was investigated using CT26 bearing mice. The results showed a dose-dependent inhibition of tumor growth in the SDJ groups compared to the model group. The number of CD8 + T and dendritic cells were increased while the Treg cells and monocytes was decreased in both the tumor and spleen in the SDJ groups. The TNF-α and INF-γ increased and the IL-1β, IL-6, and IL-10 decreased in the SDJ groups. Additionally, there was an increase in the abundance of beneficial bacteria ( Firmicutes , Coildextribacter , and Lachnospiraceae ) which contribute to intestinal health and produce short-chain fatty acids (SCFAs). On the other hand, harmful bacteria ( Muribaculaceae and uncultured Bacteroidales ) decreased. The SCFA content in the intestine also increased in the SDJ groups. Therefore, it has been showed that SDJ may elicit its effect on preventing colorectal cancer by regulating the immune system and gut microbiota.