IN VIEW OF the generally accepted fact that atherosclerosis is related to the concentration of the circulating cholesterol, efforts to prevent, retard, arrest, or reverse the atherosclerotic process have been directed towards cholesterol reduction. There are basically three approaches to cholesterol lowering employed today: diet, drugs, and surgery. The diet most commonly used to achieve cholesterol reduction is a diet low in cholesterol, with a high ratio of polyunsaturated to saturated fats (P/S ratio). These general principles were derived from the observations of epidemiologists on the importance of dietary constituents in influencing the circulating cholesterol.1-4 Kinsell et al5 studied in a controlled experiment the cholesterol lowering effect of diets containing large amounts of unsaturated fats. Connor et al6,7 and Grande et al8 demonstrated the role of dietary cholesterol in influencing serum cholesterol. The paper of Green et al9 on the use of fat-modified foods for