Hidden Gut Dysbiosis in Apparently Healthy Adults

(1) Background: Intestinal dysbiosis has been implicated in numerous gastrointestinal, metabolic, and immune-mediated disorders; however, data regarding its prevalence in asymptomatic adults remain limited. This study evaluated the prevalence and integrated profile of microbiological, functional, and immunological alterations associated with dysbiosis in apparently healthy adults undergoing intestinal microbiota screening. (2) Methods: A laboratory-based cross-sectional study included 98 asymptomatic adults. In the present study, intestinal dysbiosis was defined as a multidimensional laboratory phenotype reflecting disruption of intestinal microbial, fungal, metabolic, luminal, or mucosal immune homeostasis. Bacterial and fungal markers, short-chain fatty acids (SCFAs), fecal pH, and mucosal immune biomarkers were assessed and grouped into predefined biological domains. Dysbiosis complexity was evaluated according to the number of affected domains. (3) Results: At least one laboratory abnormality was identified in 97 participants (99.0%), while 54 (55.1%) exhibited alterations in three or more biological domains. Core bacterial imbalance was detected in 87 (88.8%) participants, inflammatory and mucosal immune abnormalities in 85 (86.7%), opportunistic bacterial overgrowth in 61 (62.2%), depletion of protective bacteria in 58 (59.2%), and fungal overgrowth in 49 (50.0%). Reduced SCFA markers were observed in 27 (27.6%) participants and altered fecal pH in 33 (33.7%). Correlation analysis revealed clustering of SCFA markers and biologically plausible associations between microbial and mucosal immune biomarkers. (4) Conclusions: Laboratory abnormalities related to intestinal dysbiosis were highly prevalent and predominantly occurred as multidomain profiles, supporting dysbiosis as a complex biological phenotype requiring integrated microbiological, metabolic, and immunological assessment.