Statistical analysis
Characteristics of the study participants were presented as mean ± standard deviation (SD) or percentage. Between-cluster differences were assessed using the one-way analysis of variance (ANOVA). We used Tukey’s test for post hoc pairwise multiple comparisons if Levene's test showed homogeneity of variance; the Games–Howell’s test was used for samples with non-homogeneous variances. The data are presented as mean ± SD. To better interpret the association of defecation status, intestinal microbiota, and habitual diet with fecal BA composition, we performed principal component analysis (PCA) on some variables that showed significant differences among clusters based on the fecal BAs composition. The variables used in the PCA were shown in Online Resources 3. All statistical analyses were performed using the Statistical Package for the Social Sciences Software Ver. 28.0 for Windows (IBM SPSS, Inc., Chicago, IL, USA); 