Comparing palmolein with different predominantly monounsaturated oils: effect on plasma lipids

Abstract

Our group has compared plasma lipids in randomised crossover trials in which approximately half the fat intake of subjects was changed from palmolein to each of three predominantly monounsaturated oils in a series of experiments in free living volunteers. With canola oil total cholesterols were lower than on palmolein; part of this reduction was due to lower HDL-cholesterol (HDL-c) so that total cholesterol/ HDL-c was only 2% lower. With olive oil mean total cholesterols were the same as on palmolein but HDL-cholesterols were a little lower and LDL-cholesterols a little higher. Plasma lipid fatty acid patterns confirmed the diet change, showing 5% higher 16 : 0 on palmolein and 11% higher 18 : 1 on olive oil. To test the possibility that lack of effect of the extra palmitic acid in the palmolein–olive oil comparison was because subjects were young, thin and active, comparison of a third oil, high oleic sunflower oil (HOSO) with palmolein was made in both young and middleaged subjects. Plasma total and LDL-cholesterols were 7% lower in the whole group on HOSO but HDL-c was also 5% lower so total cholesterol/HDL-c was only 3% lower than on palmolein. There was no difference in lowering of LDL-c on HOSO between young and older subjects. In comparisons of all three predominantly monounsaturated oils with palmolein a higher HDL-c on palmolein reduced the presumed health benefit of lower total cholesterols on canola and high oleic sunflower oil. The reason for no reduction of total cholesterol on olive oil compared with palmolein was presumably due to the higher linoleic and higher phytosterols in palmolein and higher squalene in the olive oil.