An analysis of gut dysbiosis in obesity, diabetes, and chronic gut conditions

Introduction: Gut dysbiosis is an imbalance in the microbial communities of the intestine and has been associated with numerous chronic diseases. Objectives: We aimed to compare gut dysbiosis within and across various disease states (Crohn's disease [CD], colorectal cancer [CRC], irritable bowel syndrome [IBS], and type 2 diabetes mellitus [T2DM], and obesity). Materials and Methods: Assessing comparative studies which examined levels of bacterial phyla in cases and controls. PubMed and Web of Science were searched to identify relevant studies, in which human fecal samples were used to analyze microbial flora. Results: Twenty-one studies were included, which met inclusion and exclusion criteria. Three studies were included assessing IBS, which found a decrease in Bacteroidetes in the IBS population, but inconsistent findings for other phyla. Six studies were included assessing obesity, and no consistent patterns emerged. Five studies were included examining T2DM, which found a consistent decrease in the Firmicutes/Bacteroidetes ratio in cases as compared to controls. No patterns were found for other phyla. Three studies were included examining CD, and five examining CRC. Conclusions: No consistent patterns were found for either of these diseases. While some patterns were found in bacterial phyla distribution, there were few commonalities, even in same-system disorders. However, uncovering underlying dysbiosis patterns shows great promise in furthering the understanding of disease pathogenesis and the potential for new therapeutic and diagnostic interventions. Further systematic reviews and well-controlled studies are warranted.