The concept that an excess of cholesterol in the blood may lead to hardening of the arteries has led to use of low cholesterol diets. The eating of saturated animal fats in excess, such as butter, cream, eggs, and similar substances, may result in too much cholesterol in the blood. Particularly important in low cholesterol diets is the substitution for the animal fats of polyunsaturated fats derived from corn, peanuts, cottonseed, coconut oil, and similar sources. Special margarines have been prepared for use instead of butter. In general the recommendation is to reduce weight by lowering the total diet, particularly of fat, and in cases of extraordinarily high cholesterol to take a low cholesterol diet. However, many persons using an ordinary diet do not have high cholesterol levels in the blood and do not show any signs of atherosclerosis. In each instance the physician, after determining the amount of cholesterol in the blood, will make the decision as to the special diet to be used.