Effect of Bifidobacterium animalis subsp. lactis MN-Gup on constipation and the composition of gut microbiota

Probiotics have been reported to be associated with the alleviation of constipation. The aim of this study was to detect and determine the effect of Bifidobacterium animalis subsp. lactis MN-Gup (MN-Gup) on the alleviation of constipation in BALB/c mice and humans, and to elucidate the mechanisms underlying its effect by measuring changes in the concentration of short-chain fatty acids and the composition of microbes in human faeces. BALB/c mice were given MN-Gup by gavage for 14 days. On the 8 th day of this treatment, constipation was induced by the application of diphenoxylate via gavage. The results showed that MN-Gup significantly decreased the first black stool defecation time, and significantly increased black faecal wet weight, black faecal number and the gastric-intestinal transit rate ( P <0.05), thereby relieving constipation. In humans, a randomised, double-blind, placebo-controlled trial was performed to investigate the effect of MN-Gup in adults with functional constipation. After 4 weeks of intervention with placebo or MN-Gup yogurt, constipation-related symptoms (including defecation frequency, stool consistency, straining and incomplete feeling during defecation) in the constipated subjects were significantly improved in the two groups, but not different between the groups at the end of the intervention. The concentration of acetate increased significantly in the MN-Gup group compared to the placebo group and before ingestion. Significant changes in the composition of gut microbiota were found after intake of MN-Gup yogurt when compared to placebo. The relative abundances of acetate-producing Bifidobacterium, Ruminoccaceae_UCG-002 and Ruminoccaceae_UCG-005 were significantly increased after intake of MN-Gup yogurt. These results showed that MN-Gup could relieve constipation related to increased acetate-producing Bifidobacterium, Ruminoccaceae_UCG-002 and Ruminoccaceae_UCG-005 .