Short-term egg yolk feeding in humans. Increase in apolipoprotein B and low density lipoprotein cholesterol

In animal studies, hypercholesterolemia induced by cholesterol feeding results in the plasma cholesterol being transported by lipoproteins of lower densities. Little information is available for humans. To determine the specific lipoprotein responses to dietary cholesterol challenge in humans, four volunteer subjects ingested a liquid formula diet containing 5000 mg of egg yolk cholesterol per day for 30 days and the changes in their lipoprotein fractions were examined. The high dietary cholesterol (above the range of normal diet) was associated with marked increases in apolipoprotein B and low density lipoprotein (LDL) cholesterol levels. An elevated cholesterol : triglyceride ratio in the LDL fraction indicated that the diet altered both LDL level and composition. High density lipoprotein cholesterol and apolipoprotein AI increased slightly. Very low and intermediate density lipoprotein cholesterol and apolipoprotein E levels did not increase during the diet. Thus, high dietary cholesterol was associated with major changes in LDL level and composition, but only minor changes in the other lipoprotein fractions and suggested only minor accumulation of remnant particles.