Postbiotics are preparations of inanimate microorganisms and/or their components that are beneficial to host health. Compared with probiotics, the postbiotic dose required for exerting obvious protective effects is unknown. Thus, we conducted a dose-dependent postbiotic intervention study in dextran sulfate sodium (DSS)-induced colitis rats. The trial included five rat groups, including: control without DSS/postbiotic treatment, group C; 7-day DSS treatment, group D; 14-day low, medium, and high probiotic doses (0.1, 0.2, 0.4 g/kg; groups L, M, H, respectively) after DSS induction. We found that postbiotic intervention effectively mitigated the symptoms and inflammation in colitis rats, evidenced by the improved spleen index, less severe colon tissue damage, and changes in serum cytokine levels (decreases in tumor necrosis factor-α and interleukin-1β; increase in interleukin-10) in postbiotic groups compared with group D. Moreover, the therapeutic effect was dose-dependent. Fecal metabolomics analysis revealed that the postbiotic recipients had more anti-inflammatory metabolites, namely, salicyloyl phytophingosine, podophylloxin, securinine, baicalein, and diosmetin. Fecal metagenomics analysis revealed that the postbiotic recipients had more beneficial microbes and less pro-inflammatory bacteria. This study confirmed that postbiotics are effective in alleviating colitis in a dose-dependent manner. Our findings are of interest to food scientists, clinicians, and the health food industry.
Keywords: colitis; dextran sulfate sodium; gut microbiota; inflammation; postbiotics.