Cardiovascular diseases have been the leading cause of death in the United States in recent years. Mortality statistics show that of the various cardiovascular diseases, atherosclerotic process occurring in the coronary or cerebral vessels are responsible for a large majority of deaths. A strong correlation exists between elevated plasma cholesterol and triglyceride levels and the development of atherosclerotic disease. Accordingly, it is considered desirable to reduce plasma cholesterol and triglyceride levels toward normal in treating diseases characterized by elevated blood lipid levels, e.g., coronary heart disease and stroke.