Novel therapeutic approaches based on the pathological role of gut dysbiosis on the link between nonalcoholic fatty liver disease and insulin resistance.

The growing global epidemic of obesity and type 2 diabetes mellitus has determined an increased prevalence of NAFLD (non-alcoholic fatty liver disease), making it the most common chronic liver disease in the Western world and a leading cause of liver transplantation. In the last few years, a rising number of studies conducted both on animal and human models have shown the existence of a close association between insulin resistance (IR), dysbiosis, and steatosis. However, all the mechanisms that lead to impaired permeability, inflammation, and fibrosis have not been fully clarified. Recently, new possible treatment modalities have received much attention. To reach the review purpose, a broad-ranging literature search on multidisciplinary research databases was performed using the following terms alone or in combination: "NAFLD", "gut dysbiosis", "insulin resistance", "inflammation", "probiotics", "Chinese herbs". The use of probiotics, prebiotics, symbiotics, postbiotics, fecal microbiota transplant (FMT), Chinese herbal medicine, antibiotics, diet (polyphenols and fasting diets), and minor therapies such as carbon nanoparticles, the MCJ protein, water rich in molecular hydrogen, seems to be able to improve the phenotypic pattern in NAFLD patients. In this review, we provide an overview of how IR and dysbiosis contribute to the development and progression of NAFLD, as well as the therapeutic strategies currently in use.