In this study, they fed four groups of rabbits different diets:
- Regular low-fat rabbit chow
- Regular low-fat rabbit chow plus 0.5 g cholesterol per day
- High-fat diet with 30% calories as coconut oil (saturated) and no added cholesterol
- High-fat diet with 30% calories as sunflower oil (polyunsaturated) and no added cholesterol
Total cholesterol was also the same between all groups except the cholesterol-fed group. TBARS, a measure of lipid oxidation in the blood, was elevated in the cholesterol and sunflower oil groups but not in the chow or coconut groups. Oxidation of blood lipids is one of the major factors in atherosclerosis, the vascular disease that narrows arteries and increases the risk of having a heart attack. Serum vitamin C was lower in the cholesterol-fed groups but not the others.
This supports the idea that saturated fat in the absence of excess dietary cholesterol does not necessarily increase LDL, and in fact in most animals it does not.