The Mediterranean diet improves hepatic steatosis and insulin sensitivity in individuals with non-alcoholic fatty liver disease

Background & Aims: Non-alcoholic fatty liver disease (NAFLD) affects up to 30% of the population and signifies increased risk of liver fibrosis and cirrhosis, type 2 diabetes, and cardiovascular disease. Therapies are limited. Weight loss is of benefit but is difficult to maintain. We aimed at examining the effect of the Mediterranean diet (MD), a diet high in monounsaturated fatty acids, on steatosis and insulin sensitivity, using gold standard techniques. Methods: Twelve non-diabetic subjects (6 Females/6 Males) with biopsy-proven NAFLD were recruited for a randomised, crossover 6-week dietary intervention study. All subjects undertook both the MD and a control diet, a low fat-high carbohydrate diet (LF/HCD), in random order with a 6-week wash-out period in- between. Insulin sensitivity was determined with a 3-h hyperinsulinemic-euglycemic clamp study and hepatic steatosis was assessed with localized magnetic resonance H-1 spectroscopy (H-1-MRS). Results: At baseline, subjects were abdominally obese with elevated fasting concentrations of glucose, insulin, triglycerides, ALT, and GGT. Insulin sensitivity at baseline was low (M = 2.7 +/- 1.0 mg/kg/min(-1)). Mean weight loss was not different between the two diets (p = 0.22). There was a significant relative reduction in hepatic steatosis after the MD compared with the LF/HCD: 39 +/- 4% versus 7 +/- 3%, as measured by H-1-MRS (p = 0.012). Insulin sensitivity improved with the MD, whereas after the LF/HCD there was no change (p = 0.03 between diets). Conclusions: Even without weight loss, MD reduces liver steatosis and improves insulin sensitivity in an insulin-resistant population with NAFLD, compared to current dietary advice. This diet should be further investigated in subjects with NAFLD. (C) 2013 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.