REPLACEMENT OF DIETARY SATURATED FAT WITH MONOUNSATURATED FAT - EFFECT ON ATHEROGENESIS IN CHOLESTEROL-FED RABBITS CLAMPED AT THE SAME PLASMA-CHOLESTEROL LEVEL

The aim was to compare the effect on atherogenesis of dietary monounsa turated and saturated fatty acids in cholesterol-clamped rabbits. To o btain an average plasma cholesterol concentration of 20 mmol/l in each rabbit during the 13-week cholesterol-feeding period, dietary cholest erol was adjusted weekly. The amount of fat fed daily was 10 g per rab bit in Expts A (n 23), C (n 36), and D (n 58) and 5 g per rabbit in Ex pt B (n 24). The source of monounsaturated fatty acids was olive oil i n all four experiments. The source of saturated fatty acids was butter in Expt A, lard in Expt B, coconut oil in Expt C, and butter or lard in Expt D. Generally, olive oil-fed groups received more cholesterol a nd tended to have more cholesterol in VLDL and less in LDL compared wi th groups receiving saturated fat. Analysis of variance of the combine d results of all four experiments showed that, in comparison with satu rated fat, olive oil lowered aortic cholesterol by 13 (-9-30, 95% conf idence interval) % in the aortic arch, and by 10 (-10-26) % in the tho racic aorta, which was not significant, In the comparison with olive o il, no differences in effects on aortic cholesterol content were detec ted between butter, lard and coconut oil. These findings do not suppor t the view that replacement of dietary saturated fat with olive oil ha s a major impact on the development of atherosclerosis in addition to that accounted for by changes in plasma cholesterol levels.