Gut microbiota and metabolic syndrome

Abstract

Gut microbiota exerts a significant role in the pathogenesis of the metabolic syndrome, as confirmed by studies conducted both on humans and animal models. Gut microbial composition and functions are strongly influenced by diet. This complex intestinal “superorganism” seems to affect host metabolic balance modulating energy absorption, gut motility, appetite, glucose and lipid metabolism, as well as hepatic fatty storage. An impairment of the fine balance between gut microbes and host’s immune system could culminate in the intestinal translocation of bacterial fragments and the development of “metabolic endotoxemia”, leading to systemic inflammation and insulin resistance. Diet induced weight-loss and bariatric surgery promote significant changes of gut microbial composition, that seem to affect the success, or the inefficacy, of treatment strategies. Manipulation of gut microbiota through the administration of prebiotics or probiotics could reduce intestinal low grade inflammation and improve gut barrier integrity, thus, ameliorating metabolic balance and promoting weight loss. However, further evidence is needed to better understand their clinical impact and therapeutic use.

Keywords: Gut microbiota, Metabolic syndrome, Obesity, Diabetes, Non-alcoholic fatty liver disease, Probiotic, Prebiotic, Bariatric surgery

Core tip: The present review offers a summary of available studies exploring the pathogenic role of gut microbiota in the development of metabolic syndrome, subdividing experimental evidences coming from animal models and human subjects, since their results are not always comparable. The relative influences of dietary intake on gut microbial composition and functions are also explored, as well as the effects on intestinal microhabitat exerted by diet-induced weight loss and bariatric surgery. Finally a critical evaluation of the available evidences on probiotic and prebiotics is reported, delineating their potential clinical impact.