OLIVE OIL AND RAPESEED OIL DIFFER IN THEIR EFFECT ON PLASMA LOW-DENSITY-LIPOPROTEIN METABOLISM IN THE GUINEA-PIG

The effects of olive oil and rapeseed oil, two different high-oleic-ac id oils, on plasma LDL and hepatic cholesterol metabolism were compare d in guinea-pigs. Animals were fed on semipurified diet containing 150 g fat/kg as either olive oil (OL), rapeseed oil plus 100 g palm oil/k g (C-P) or olive oil plus 350 g safflowerseed oil/kg (OL-S). Olive oil was enriched with safflowerseed oil (OL-S diet) to increase linoleic acid and to decrease palmitic acid concentrations, in order to evaluat e whether differences in plasma LDL concentrations were due to intrins ic effects of the specific oil (rapeseed or olive oil) or to differenc es in the content of specific fatty acids. No differences due to dieta ry fat source were found in plasma total and HDL-cholesterol levels or in LDL composition. Plasma LDL-cholesterol levels were lower on the C -P diet than the OL diet (P<0.05) while plasma LDL-cholesterol levels in animals fed on the OL-S diet were not significantly different from either dietary group (P>0.05). The number of hepatic apo B/E (LDL) rec eptors was on average 25% higher in animals fed on the C-P diet compar ed with those fed on diets containing olive oil. Likewise, cardiac mus cle lipoprotein lipase (EC 3.1.1.34) activity was significantly higher in the C-P group than in the OL and OL-S dietary groups. Dietary fat source had no effect on hepatic cholesterol levels or 3-hydroxy-3-meth ylglutaryl (HMG) CoA reductase (EC 1.1.1.34) activity. The results ind icate that olive oil and rapeseed oil, both rich sources of monounsatu rated fatty acids, differ in their effect on LDL metabolism in the gui nea-pig.