The effects of different dietary fats and cholesterol on serum lipoprotein concentrations in hamsters

(i) We have studied the effect of dietary cholesterol and fat on lipoprotein concentrations in the male Golden Syrian hamster. (ii) On a low fat diet, dietary cholesterol increased the cholesterol concentration in all the major serum lipoprotein fractions. It also increased the storage of cholesterol ester in the liver. (iii) In the absence of added dietary cholesterol, additional dietary fat had little influence on serum or hepatic cholesterol concentrations, and this is irrespective of the nature of the dietary fat. (iv) In the presence of 0.12% (w/w) cholesterol, lard (rich in saturated fatty acids) increased serum VLDL cholesterol and triacylglycerol concentrations. By contrast, olive oil (rich in oleic acid) had no effect on VLDL lipid concentrations and sunflower oil, rich linoleic acid, reduced them. (v) Lard also increased serum LDL cholesterol concentrations in cholesterol-fed animals. Olive oil reduced LDL cholesterol concentrations and sunflower oil had no effect. (vi) In cholesterol-fed animals, lard had no effect on the hepatic cholesterol ester concentration, while both olive and sunflower oil increased it. This increase was significantly higher in olive oil-fed hamsters compared to those fed sunflower oil. (vii) Thus, in this species, the primary effects of dietary fat on lipoprotein metabolism appear to represent a modulation of the effects of dietary cholesterol. In cholesterol-fed hamsters we confirm the hypercholesterolaemic effects of saturated fatty acids and highlight important differences in the effects of mono- and poly-unsaturated fatty acids on lipoprotein metabolism.