Coffee components and Non-Alcoholic Fatty Liver Disease

Epidemiological data associate coffee consumption with a lower prevalence of chronic liver diseases, and with a reduced risk of elevated liver enzyme levels (γ-glutamyltransferase and alanine aminotransferase), of advanced liver disease and its complications as well as of hepatocellular carcinoma. The knowledge of the mechanisms underlying these effects as well as the individuation of coffee components which are responsible for these properties, are still lacking. In this study 1.5 mL/die of decaffeinated coffee or its polyphenols or melanoidins (corresponding to ~2 cups of American- or 6 cups of espresso-coffee for a 70 kg man) were added for 8 weeks to the drinking water of rats who were being fed with high-fat high-calorie solid diet (HFD) for the previous 4 weeks. At 12nd week HFD+water rats showed a clinical picture typical of advanced non-alcoholic steatohepatitis (NASH) compared to control rats (normal diet+water). In comparison HFD+coffee rats showed: i) reduced hepatic fat and collagen as well as reduced serum ALT and triglycerides; ii) a double fold GSH/GSSG ratio in both serum and liver; iii) reduced serum malondialdehyde (lipid peroxidation) and increased FRAP (reducing activity); iv) reduced expression of TNF-α, tTG and TGF-β and increased expression of adiponectin-receptor and PPAR-α in liver tissue; v) reduced hepatic concentrations of pro-inflammatory TNF-α and IFN-γ and increased anti-inflammatory IL-4 and IL-10. Conclusions: Data demonstrated that coffee consumption protects liver from damage caused by HFD. This effect was mediated by reduction of: hepatic fat accumulation, through increased fatty acid β-oxidation; systemic and liver oxidative stress, through glutathione system; liver inflammation through modulation of genes, expression and concentrations of proteins and cytokines related to inflammation.