Cholesterol response and foam cell formation in hamsters fed two levels of saturated fat and various levels of cholesterol

Two levels of saturated fat (31 and 39% of the calories) and several levels of cholesterol were fed to weanling male hamsters in order to evaluate their atherogenicity and foam cell formation in the aortic arch. Diets contained 5% cellulose, 20% casein, and either 15% butterfat plus 0, 0.05, 0.5 or 3% cholesterol (C) or 20% butterfat plus 0 or 0.5% C. Total plasma cholesterol (TC) was significantly (P less than or equal to 0.05) elevated when dietary fat was increased from 15 to 20% with no added cholesterol (232 vs 262 mg/dl). Addition of 0.05, 0.5 or 3% C to 15% fat diet, or 0.5% C to 20% fat diet resulted in significant TC elevations compared with their respective no added C controls (301, 383 and 533 vs 232 and 490 vs 262 mg/dl, respectively). With 0.5% added C, plasma cholesterol values with 20% fat diet were significantly greater than those with 15% fat (490 vs 383 mg/dl). Increased TC was mainly due to significant elevations in VLDL and LDL cholesterol levels, which resulted in a significant decrease in HDL/LDL cholesterol ratios. Elevations in TC and reductions in HDL/LDL cholesterol ratios were similar in hamsters fed 15% fat with 3% cholesterol or 20% fat with 0.5% cholesterol. Liver cholesterol increased significantly with increased dietary cholesterol up to 0.5%. Foam cell formation was significantly greater in animals fed 0.5 or 3% added cholesterol with 15 or 20% fat diet compared with low (0 or 0.05% added) C diets. Significant plasma and liver cholesterol elevations, lower HDL/LDL cholesterol ratios and increased foam cell formation indicate that a diet containing a higher level of saturated fat and lower cholesterol is as atherogenic as a diet with lower fat and high cholesterol. Significant foam cell formation in 6 weeks by feeding 0.5% cholesterol and 20% butterfat diet to hamsters suggests that this model is suitable for atherosclerosis progression and regression studies within a reasonable time frame.