Antiatherogenic effect of olive and corn oils in cholesterol-fed rabbits with the same plasma cholesterol levels

Two groups of 18 rabbits were fed isocaloric, cholesterol-enriched diets for 8 weeks. The diet for one group was supplemented with 5% corn oil. The concentration of cholesterol in plasma was determined weekly and the amount of cholesterol in the diet was adjusted individually so that each rabbit had a mean plasma cholesterol concentration of about 45 mM during the experimental period. The aortic cholesterol concentrations were 122 +/- 29 and 193 +/- 38 (mean +/- SEM) mumol/g protein for the corn-oil group and the control group, respectively (p less than 0.05). In a similar experiment, each of 36 rabbits was given a mean plasma cholesterol level of about 20 mM over a period of 12 weeks. One-third of the rabbits received 10% to 15% corn oil, another third 10% to 15% olive oil, while the last third served as a control group. The aortic cholesterol concentrations were 98 +/- 25, 57 +/- 9, and 131 +/- 32 mumol/g protein, respectively. The value for the olive-oil group was significantly (p less than 0.01) lower than the value for the control group. The triglyceride concentrations and the distributions of cholesterol between HDL, LDL, and VLDL in plasma showed no significant differences between the plant-oil groups and their control groups. This suggests that plant oils have a direct effect on the aortic cholesterol metabolism.