Scope: Obesity is associated with non-alcoholic fatty liver disease (NAFLD) but effective treatment is limited. Dietary supplementation of n-3 polyunsaturated fatty acids, specifically alpha linolenic acid (ALA), can resolve intrahepatic lipid content (IHL). This study investigated the effect of daily supplementation of either refined rapeseed (RA), which contains high amounts of ALA, or refined olive (OL) oil on IHL and glucose metabolism in NAFLD patients.

Methods and results: 27 obese men consumed an isocaloric diet including either 50 g of RA or OL daily for eight weeks. Hepatic proton magnetic resonance spectroscopy, hyperinsulinemic-euglycemic clamp studies and blood tests were performed before and at the end of the study. BMI did not change for RA or OL. At eight weeks a significant reduction in IHL was observed for RA (13.1±1.6 before versus 11.1±1.6 % after intervention) versus OL (13.3±2.5 before versus 15.7±2.7 % after intervention). For RA, a 21% reduction (P<0.02) in serum free fatty acids (FFA) and a 1.68-fold increase (P = 0.03) of serum interleukin-6 (IL-6) was observed after eight weeks.

Conclusion: RA has a beneficial effect on hepatic lipid metabolism as shown by reduced IHL and serum FFA. RA induced IL-6 production seems to be liver protective confirming previous results. This article is protected by copyright. All rights reserved.

Keywords: hepatic steatosis; obesity; olive oil; rapeseed oil; serum lipids.