Comparison of an oleic acid enriched-diet vs NCEP-I diet on LDL susceptibility to oxidative modifications

Objective: The objective of this trial was to compare the effect on the sus ceptibility of plasma Low Density Lipoprotein (LDL) to oxidative modificati ons of consumption of two oleic rich diets, prepared with two different pla nt oils, virgin olive oil (OL)(1) and refined high monounsaturated fatty ac ids (MUFA sunflower oil (SU)), with the susceptibility of plasma LDL to oxi dation after an National Cholesterol Education Program step 1 (NCEP-I) phas e diet. Design: A randomized crossover design. Subjects and interventions: Twenty-two healthy normolipidemic young males c onsumed an NCEP-I diet for a 4-week period. Subjects were then assigned to two diets each of 4-weeks duration. Group one was placed on an olive oil en riched diet (40% fat, 22% MUFA) followed by a 4-week period of a MUFA diet enriched in sunflower oil (40% fat, 22% MUFA). In group two, the order of t he diets was reversed. Results: Both MUFA diets induced a decrease in saturated (14 : 0, 16 : 0, a nd 18 : 0) and an increase in monounsaturated and polyunsaturated n-6 (18 : 2, 20 : 3, and 20 : 5) plasma LDL-phospholipid fatty acids, compared to th e NCEP-I diet (P < 0.01). No significant differences in lag times were obse rved between the olive oil and the NCEP-I diet periods. However there was a greater inhibition time (P < 0.001) when subjects consumed the MUFA rich s unflower oil diet compared to the NCEP-I diet. These differences were proba bly related to the relative enrichment of plasma LDL particles in cc-tocoph erol due to the high vitamin E content of the MUFA-rich sunflower oil. Inde ed, the alpha-tocopherol content was positively correlated with lag time (r = 0.338; P < 0.008). Conclusion: Our findings suggest that changes in plasma LDL alpha-tocophero l content with practical solid-food diets can decrease its susceptibility t o oxidation.