Patients with nonalcoholic fatty liver disease reduced their liver steatosis and improved their insulin sensitivity by adhering to a 6-week Mediterranean diet without experiencing weight loss in a recent study.
Using a cross-over dietary intervention study, researchers compared the results of 12 participants (six men, six women), all with biopsy-proven nonalcoholic fatty liver disease (NAFLD). All were randomly assigned to both a Mediterranean diet and a low-fat, high-carbohydrate diet (LF/HCD) with a 6-week washout period between diets. The MD was high in monounsaturated fats from olive oil and omega 3 polyunsaturated fatty acids. The LF/HCD was low in saturated and unsaturated fats and included more carbohydrates than the MD.
Baseline values for all participants were not significantly different when starting with either the MD or LF/HCD. Intrahepatic lipids (IHL) used to indicate hepatic steatosis was measured by magnetic resonance spectroscopy, and insulin sensitivity also was assessed.
Participants were abdominally obese with elevated mean fasting serum glucose concentrations, ALT, triglycerides and gamma-glutamyl transpeptidase. The mean IHL was elevated at 11.2% ± 2.1%, while the mean insulin sensitivity was low (M=2.7 ± 1 mg/kg/min–1).
Reduction in IHL after the MD was significantly greater than after the LF/HCD (39% ± 4% vs. 7% ± 3%; P=.03 between diets). Insulin sensitivity also improved after the MD, but remained unchanged after the LF/HCD (P=.03). Mean weight loss between diets was not significant, nor was the difference in weight change for participants regardless of which diet they followed first.
“This study has demonstrated that in just 6 weeks … the Mediterranean diet can result in a relative reduction of liver fat, even without a change in weight,” the researchers concluded. “To our knowledge, this is the first trial to demonstrate in a randomized, controlled study, a reduction in liver fat and improvement in insulin sensitivity … in subjects with NAFLD.
“We suggest that … the MD may become the backbone of NAFLD therapy; however, larger, longer-term studies are needed to explore the durability of the benefits of the MD.”