Comparison of the effects of rapeseed oil, olive oil and hydrogenated plant oil on postprandial lipids and fatty acid oxidation

Olive and rapeseed oil are both considered beneficial for lipid metabolism because of their high content of monounsaturated fatty acids. We compared postprandial lipid metabolism after test meals with these plant oils including hydrogenated plant oil as a reference. Subjects and Methods: Twenty normolipidemic subjects (age: 25.1±4.9 year, M±SEM, body mass index 21.5±0.6 kg/m) underwent three one week diet periods in a cross over study design with consumption of muffins containing either olive, rapeseed or hydrogenated oil. On the seventh day of each diet week subjects consumed a test meal with 0.5 g of the corresponding oil and 0.5 mg C labelled linoleic acid per kg body weight after a 12 h fast. Blood was sampled before the meal and in hourly intervals thereafter. Breath was collected at baseline and in half hourly intervals. After 8 hours sampling was stopped. Results: Fasted plasma phospholipid fatty acids showed significantly higher oleic acid after olive oil (12.3±0.3 %), significantly higher α-linolenic acid after rapeseed oil (0.32±0.03 %) and significantly higher palmitic acid after hydrogenated oil (30.3±0.3 %), although stool fat indicated that hydrogenated oil was not adequately absorbed. Fasted plasma triacylglycerol and cholesterol (total, LDL, VLDL and HDL) were not different between the diets. Postprandial increase of triacylglycerol was similar with olive and rapeseed oil, but lower after hydrogenated oil reflecting its poor absorption. Cumulative recovery of C after 8 h was 10.7±0.6 % after olive oil, 11.6±0.6 % after hydrogenated oil and 13.1±0.8 % after rapeseed oil, indicating significantly greater linoleic oxidation after rapeseed oil. Conclusion: Postprandial lipid metabolism is similar with rapeseed and olive oils. Rapeseed oil enhances linoleic acid oxidation, possibly mediated by an interaction of n-3 fatty acids with peroxisome proliferator activated receptors.