Dietary Polyphenols and Non-Alcoholic Fatty Liver Disease

Abstract

Non-alcoholic fatty liver disease (NAFLD), which is emerging as a major public health issue worldwide, is characterized by a wide spectrum of liver disorders, ranging from simple fat accumulation in hepatocytes, also known as steatosis, to non-alcoholic steatohepatitis (NASH) and cirrhosis. At present, the pharmacological treatment of NAFLD is still debated and dietary strategies for the prevention and the treatment of this condition are strongly considered. Polyphenols are a group of plant-derived compounds whose anti-inflammatory and antioxidant properties are associated with a low prevalence of metabolic diseases, including obesity, hypertension, and insulin resistance. Since inflammation and oxidative stress are the main risk factors involved in the pathogenesis of NAFLD, recent studies suggest that the consumption of polyphenol-rich diets is involved in the prevention and treatment of NAFLD. However, few clinical trials are available on human subjects with NAFLD. Here, we reviewed the emerging existing evidence on the potential use of polyphenols to treat NAFLD. After introducing the physiopathology of NAFLD, we focused on the most investigated phenolic compounds in the setting of NAFLD and described their potential benefits, starting from basic science studies to animal models and human trials.

Keywords: antioxidant; food; insulin-resistance; steatohepatitis; steatosis.

Figure 1

Pathogenic mechanisms involved in the progression of NAFLD and possible sites of polyphenols action (green triangles). (CYP2E1: Cytochrome P450 2E1, ROS: reactive oxygen species). (A)Normal liver parenchyma is composed of small lobules of hexagonal shape with portal tracts at the apices; (B) hepatocytes contain one or more large fat droplets that displace the nucleus to an eccentric position; and(C) ballooning degeneration of hepatocytes, scattered inflammation, and apoptotic bodies.

Figure 2

Chemical classification of polyphenols.

Figure 3

Representation of the chemical structure of 2-Phenylchroman, shows the basicnucleus of flavonoids, indicating the chroman (A,C) and the aromatic ring in position 2 (B).