Coffee and Non-Alcoholic Fatty Liver Disease: the role of polyphenols and melanoidins

Epidemiological data associate coffee consumption with a reduced prevalence and risk of chronic and advanced liver disease, elevated liver enzymes, and hepatocellular carcinoma. Knowledge of the underlying mechanisms and the role of coffee components is still lacking. In this study, 1.5 mL/day of decaffeinated coffee or its polyphenols or melanoidins (~2 cups of filtered coffee or 6 cups of espresso coffee for a 70-kg person) were added for 8 weeks to the drinking water of rats who were being fed a high-fat, high-calorie solid diet (HFD) for the previous 4 weeks. At week 12, HFD+water rats showed a clinical picture typical of advanced nonalcoholic steatohepatitis compared with control rats (normal diet+water). In comparison, HFD+coffee rats showed: (1) reduced hepatic fat and collagen, as well as reduced serum alanine aminotransferase and triglycerides; (2) a two-fold GSH/GSSG ratio in both serum and liver; (3) reduced serum malondialdehyde (lipid peroxidation) and increased FRAP (reducing activity); (4) reduced expression of TNF-α, tissue transglutaminase, and TGF-β and increased expression of adiponectin receptor and PPAR-α in liver tissue; and (5) reduced hepatic concentrations of proinflammatory TNF-α and interferon-γ and increased anti-inflammatory IL-4 and IL-10. In conclusion our data demonstrate that coffee consumption protects the liver from damage caused by a HFD. This effect was mediated by a reduction in hepatic fat accumulation (through increased fatty acid β-oxidation); systemic and liver oxidative stress (through the glutathione system); liver inflammation (through modulation of genes); and expression and concentrations of proteins and cytokines related to inflammation