CURRENT available knowledge is sufficient to warrant a general statement regarding the relation of diet to the possible prevention of atherosclerosis (Appendix I). A heart attack, also called coronary thrombosis or myocardial infarction, or just plain "coronary," is almost always caused by atherosclerosis (arteriosclerosis or hardening of the arteries). Stroke, or apoplexy, is often caused by the same condition. The problem of preventing or retarding these diseases is, then, one of preventing or retarding atherosclerosis. How Does Atherosclerosis Develop?— Athero-Atherosclerosis is a complex disease of the arteries. It is known that a number of factors influence or are related to its development. Among these factors are a high content in the blood of a type of fat called cholesterol, elevation of blood pressure above normal, presence of diabetes, obesity, and a habit of excessive cigarette smoking. Age, sex, and heredity are also important. What Types of Research Relate Diet to