Protective role of coffee in non-alcoholic fatty liver disease (NAFLD)

The benefits of coffee on abnormal liver biochemistry, cirrhosis and hepatocellular carcinoma have been reported, but there is a lack of satisfactory explanation. Thus, this study aims to investigate if coffee use has any relationship with bright liver, measured by ultrasound bright liver score (BLS), in patients with non-alcoholic fatty liver disease (NAFLD), and which relationship, if any, is present with BMI and insulin resistance.

This study was performed on 245 patients, 137 with NAFLD and 108 controls. Coffee drinking was defined according to the absolute number of cups of coffee (only espresso coffee), and also graded as 1 (0 cups of coffee/day), 2 (1-2 cups of coffee/day) 3 (≥3 cups of coffee/day). Insulin resistance was assessed by homoeostasis model-insulin resistance index (HOMA).

Less fatty liver involvement is present in coffee vs. non-coffee drinkers. Odds ratios show that obesity, higher insulin resistance, lower HDL cholesterol, older age and arterial hypertension are associated with a greater risk of more severe BLS; to the contrary, coffee drinking is associated with less severe BLS. In the multiple logistic regression (MLR) model, number of cups of coffee, HOMA and BMI account for 35.8% of the variance to BLS. Coffee use is inversely associated with the degree of bright liver, along with insulin resistance and obesity, which, to the contrary, are directly associated with greater likelihood and severity of bright liver appearance.

A possible opposite, if not antagonistic, role of coffee with regard to overweightness and insulin resistance, similar to that reported in hepatocarcinoma and cirrhosis, is envisaged in the natural history of NAFLD.