Plasma cholesterol levels and liver cholesterol biosynthesis in rabbits fed commercial or semisynthetic diets with and without added fats or oils

Abstract

Rabbits were fed semisynthetic or commercial diets, low in fat or containing 15 % by weight of various added fats or oils, and after 2 weeks on diet, plasma cholesterols were measured and the ability of liver slices to incorporate acetate into cholesterol and fatty acids was determined. Plasma cholesterol levels were high in rabbits fed semisynthetic diets containing no fat or saturated fats. They were normal or only slightly elevated on the corresponding commercial diets and on either semisynthetic or commercial diets containing polyunsaturated oils. Addition of casein to commercial diets elevated plasma cholesterol except when polyunsaturated oils were present but added dextrose had little effect. Growth was better on commercial than on semisynthetic diets and was stimulated by adding casein but was inhibited by adding dextrose to the commercial diet. Acetate incorporation into cholesterol was generally lower on semisynthetic than on commercial diets, and added fats had no consistent effects. Incorporation into fatty acids tended to be higher on semisynthetic than on commercial diets but was decreased by adding fats to either diet. Liver levels of cholesterol and fatty acids were generally higher on high fat diets. Addition of casein to commercial diet depressed acetate incorporation into cholesterol. Added dextrose had no effect and neither casein nor dextrose had any consistent effect on incorporation into fatty acids.