Plain language summary
Primary bile acids (priBAs) are synthesised from cholesterol in the human liver, conjugated with either taurine or glycine [amino acids], and secreted into the intestinal tract, where they dissolve dietary lipids. Diet is a modifiable factor that can influence defecation status, BAs, and intestinal microbiota. The aim of this study was to identify associations among defecation status, intestinal microbiota, and diet by examining faecal BA composition in community-dwelling young participants. This study was a cross-sectional study which enrolled 70 students. Results showed that 20.9% of the participants had high faecal BA levels with predominantly priBAs. This cluster was associated with an increased relative abundance of Clostridium subcluster XIVa [bacteria], increased frequency of normal faeces, and decreased relative abundance of Bacteroides and Clostridium cluster IV [bacteria]. Conversely, high levels of cytotoxic [toxic to cells] secondary BA (secBA) were associated with low normal defecation frequency, low insoluble fibre intake, and high animal fat intake. Authors concluded that among community-dwelling young adults, secBA production is affected by both dietary and lifestyle related factors. Thus, their findings may inform novel strategies for preventing colorectal cancer and cholelithiasis.
Abstract
PURPOSE Bile acid (BA) metabolism by intestinal bacteria is associated with the risk of gastrointestinal diseases; additionally, its control has become a modern strategy for treating metabolic diseases. This cross-sectional study investigated the influence of defecation status, intestinal microbiota, and habitual diet on fecal BA composition in 67 community-dwelling young participants. METHODS Feces were collected for intestinal microbiota and BA analyses; data about defecation status and dietary habits were collected using the Bristol stool form scales and a brief-type self-administered diet history questionnaire, respectively. The participants were categorized into four clusters based on their fecal BA composition, according to cluster analysis, and tertiles based on deoxycholic acid (DCA) and lithocholic acid (LCA) levels. RESULTS The high primary BA (priBA) cluster with high fecal cholic acid (CA) and chenodeoxycholic acid (CDCA) levels had the highest frequency of normal feces, whereas the second BA (secBA) cluster with high levels of fecal DCA and LCA had the lowest. Alternately, the high-priBA cluster had a distinct intestinal microbiota, with higher Clostridium subcluster XIVa and lower Clostridium cluster IV and Bacteroides. The low-secBA cluster with low fecal DCA and LCA levels had the lowest animal fat intake. Nevertheless, the insoluble fiber intake of the high-priBA cluster was significantly higher than that of the high-secBA cluster. CONCLUSION High fecal CA and CDCA levels were associated with distinct intestinal microbiota. Conversely, high levels of cytotoxic DCA and LCA were associated with increased animal fat intake and decreased frequency of normal feces and insoluble fiber intake. CLINICAL TRIAL REGISTRY University Hospital Medical Information Network (UMIN) Center system (UMIN000045639); date of registration: 15/11/2019.
Methodological quality
Jadad score
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Allocation concealment
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