Comparison of diets supplemented with fish oil or olive oil on plasma lipoproteins in insulin-dependent diabetics

Abstract

This study was designed to compare changes in high-density lipoprotein (HDL)- and low-density lipoprotein (LDL)-cholesterol in normolipidaemic male insulin-dependent diabetics (IDD) following dietary supplementation with either the fish oil concentrate Max EPA or olive oil. The contribution of the small quantity of cholesterol in Max EPA to these changes was also examined. Twenty-seven subjects were matched in groups of three and randomly allocated to one of three treatment groups of nine subjects each. Subjects were given 15 1-g capsules of oil daily for 3 weeks, consisting of either Max EPA, olive oil, or olive oil to which was added the same amount of cholesterol as contained in Max EPA, respectively. There was a significant increase in eicosapentaenoic acid, and a decrease in arachidonic acid, in the platelet membrane phospholipids of subjects taking Max EPA. In this group, there was an approximately 30% increase in serum HDL 2-cholesterol (0.59 ± 0.07 to 0.77 ± 0.11 mmol/L, mean ± SEM; P < .01) and a corresponding decrease in HDL 3-cholesterol (0.79 ± 0.03 to 0.71 ± 0.03 mmol/L; P < .05). Although total and LDL-cholesterol concentrations were also higher after Max EPA, the changes were not significant. Triglycerides were significantly decreased by Max EPA. There were no significant changes in lipids in the groups given olive oil. These results show that compared with olive oil, dietary supplementation with Max EPA substantially increases HDL 2-cholesterol in insulin-dependent diabetics. This is most likely due to a selective effect of ω3 fatty acids. An increase of this proportion in the cardioprotective HDL 2-cholesterol, if sustained over time, could have a major impact on vascular health in diabetics.