Scope The characteristics of gut microbiota and host metabolism are hypothesized to be associated with constipation status, but the regulation mechanism is not fully understood. Thus, the current study investigates the effect of constipation symptoms on gut functionality following the modulation of gut microbiota and metabolites via dietary fiber intervention. Methods and results Constipation causes a significantly reduced short‐chain fatty acids (SCFAs) production and a higher level of iso‐butyrate. The feces of constipated people are characterized with inhibited Faecalibacterium, Ruminococcaceae and Roseburia abundance. Desulfovibrionaceae is identified to be an important endotoxin producer in constipated patients, and a butyrate‐enriched SCFAs profile achieved by dietary fiber supplement accelerates gastrointestinal transit and increases the thickness of the mucosal layer, possibly through triggering the secretion of colonic hormones and enhancing the expression of tight junction proteins for maintaining intestinal barrier integrity. More importantly, an interacting regulatory mechanism among SCFAs, in particular butyrate and propionate, may be involved in signaling between the microbiome and host cells in the colon. Conclusion Gut microbiota, characterized with enriched butyrate‐producing and depressed Desulfovibrionaceae bacteria, attenuates constipation symptoms through promoting intestinal hormones secretion and maintaining gut barrier integrity.

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BACKGROUND Diabetes mellitus is a serious chronic disease, characterized by hyperglycemia. This study administered either β‐mannanase‐treated yeast cell autolysis supernatant (YCS) or yeast cell‐wall residues after autolysis (YCR) to investigate their influence on the alleviation of diabetes in a diabetic mouse model. RESULTS Application of either YCS or YCR led to body weight gain, blood glucose reduction, and an improvement in lipid composition in the diabetic mice. Administration of YCS was more effective in inhibiting oxidative stress than YCR. The expression of PPARα and CPT1α was enhanced, improving lipid biosynthesis, and Trx1 and HIF‐1‐α genes were downregulated due to the activation of thioredoxin following the interventions, indicating that the processes of lipid metabolism and oxidative stress were heavily involved in the reduction of diabetic characteristics following the interventions. The current study revealed that consumption of YCR also led to a reduction in hyperglycemia, this being associated with its richness in mineral elements, such as chromium and selenium. CONCLUSION This study may highlight the potential of both YCS and YCR as functional ingredients in dietary formula for improving diabetic syndromes. © 2019 Society of Chemical Industry