Abstract: This study aimed to explore the improvement effect of xylooligosaccharides (XOS) on chronic diarrhea. According to the principle of randomized parallel controlled experiments, patients with clinical chronic diarrhea were recruited and randomly divided into three groups, a placebo group (CK, taking 3 g of maltodextrin per day), a low-dose XOS group (3X, taking 3 g of XOS per day) and a high-dose XOS group (6X, taking 6 g of XOS per day). The diarrhea symptom scores, serum biochemical indexes, fecal short-chain fatty acids and gut microbiota were analyzed after four weeks of intervention. Then, the fecal bacterial supernatant of the patients in each intervention group was administered by gavage to mice for 24 consecutive days, and the intestinal permeability and the levels of inflammatory factors were measured after 12 h fasting on the 25th day. The results showed that diarrhea symptoms and lipid metabolism tended to be improved in the intervention groups compared to the placebo group, and fecal butyric acid levels increased. The relative abundance of Blautia, Bifidobacterium, and Lachnospiraceae_unclassified were increased, while the relative abundance of Prevotella was decreased. Compared to the placebo group, the intestinal barrier tended to be stable in the mice gavaged with the fecal bacterial supernatant of the XOS intervention groups, colonic inflammation was significantly alleviated, the level of serum D-lactic acid (D-LA) was significantly decreased (P < 0.05 or 0.01), and the expression of tight junction protein (zonula occludens-1 (ZO-1) and occludin) was up-regulated. These results indicate that XOS are effective in improving chronic diarrhea, and are expected to alleviate chronic diarrhea.

Key words: chronic diarrhea; xylooligosaccharides; fecal microbiota transplantation; inflammatory cytokines; gut microbiota