Altered Gut Microbiota: A Link Between Diet and the Metabolic Syndrome

Diet with increased intake of energy-rich foods has long been implicated in the etiology of metabolic syndrome. In recent years, an increasing body of evidence has emerged that suggests that the intestinal microbial flora or "gut microbiota" may play a crucial role in the development of metabolic syndrome and associated disorders. Studies on animals and humans have shown that diet-induced changes in gut microbiota may be causally involved in the pathogenesis of metabolic syndrome. This article reviews the available evidence from studies on animal models and humans with or without metabolic syndrome that have investigated the impact of diet on intestinal microbial composition and activity on the metabolic syndrome. The underlying mechanisms or pathways that link diet and altered gut microbiota to the development of metabolic syndrome are discussed with special emphasis on gut microbiota-induced changes in intestinal short-chain fatty acids, metabolic endotoxemia, low-grade systemic inflammation, and innate immune system activation and their inter-relationships to metabolic syndrome.