(HDLs, which are higher in protein and lower in cholesterol than LDLs) transport cholesterol from the tissues to the liver. HDLs are also called "good cholesterol," because in this form cholesterol is more easily removed from the blood by the liver and excreted in bile.
A diet low in total fat, with most of it unsaturated fat, tends to raise HDL levels and lower LDL levels. The benefit is the delaying of atherosclerosis and coronary artery disease. A simple blood test called a lipid profile (or lipid panel) can determine levels of total cholesterol, triglycerides, HDLs, and LDLs. A high HDL level, above 50 mg/dl, is considered good, but some researchers now believe that the LDL level is more important and should be as low as possible, below 100 mg/dl.
Other factors contribute to coronary artery disease, such as heredity, smoking, being overweight, and lack of exercise. Diet alone cannot prevent atherosclerosis. However, a diet low in total fat and high in polyunsaturated fats is a good start (Seeley, 2003).