particularly liquid oils, have largely replaced them in cooking. Most vegetable oils are naturally high in polyunsaturated fats, having 50 to 90 percent polyunsaturates. Chocolate ("cocoa butter"), coconut, coconut oil, and palm oils are high in saturated fats. These are sometimes referred to in food labels as "tropical oils". For comparison purposes, butterfat is 60 percent saturated fat.

Of the commercially available cooking and salad oils, safflower and sunflower oils have the most polyunsaturates; about 86 percent. Soy and corn oils have somewhat less; about 82 percent. Peanut oil has 78 percent polyunsaturates. Cottonseed oil is relatively low in polyunsaturates at 70 percent. Some commercial cooking oils are blended oils; the label must be consulted to determine the relative amounts of saturated and polyunsaturated oils present. Even a single brand may vary from time to time in the proportion of oils present, depending on market conditions. "Hydrogenating", or "saturating" an oil which is normally unsaturated is done to harden the oil, producing the solid shortening used in baking. Hydrogenating also helps retard spoilage. Olive and canola oils are in a class called "monounsaturated". Olive oil has only 12 percent polyunsaturated component, and is about 15 percent saturated oils. The monounsaturated fraction of olive oil, about 73 percent, is not thought to be associated with increased cholesterol.

Decreasing total fat intake, for weight control, and limiting saturated fats, for cholesterol control, has been shown to decrease the risk of coronary artery disease. Increasing numbers of people are making the necessary changes in their diet and life style to protect themselves  from arteriosclerotic diseases. The essentials of a low saturated fat diet are:
1) Limiting sources of saturated fat, including fats in beef, pork, butter, lard, hydrogenated oils, whole milk, cream, ice cream, whole milk cheese, palm oil, coconut oil, avocados. This means decreasing the amount of beef and pork in the diet and increasing poultry, fish, and shellfish. It means cutting off and discarding all visible fat from meat servings, and discarding the skin of poultry, in which fat is concentrated.
2) Increasing the proportion of unsaturated oil sources, which are safflower oil, sunflower seed oil, soybean oil, corn oil, fish and shell fish. Soft margarines are to be substituted for butter, liquid vegetable oils used for baking and frying instead of solid shortenings or lard. Low fat salad dressings are available which use emulsifiers and thickeners to reproduce the viscous consistency usually associated with oil.

Cholesterol and Lipoproteins
Cholesterol is a much misunderstood substance. It has been characterized as the villain responsible for heart attack, but it is also essential to life. Chemically, cholesterol is an alcohol, with a pearly, waxy appearance, often described as "fat . Cholesterol is available in foods, but is also synthesized by the human body. About 93 percent of the total cholesterol in the body is found within cell membranes; only 7 percent actually circulates in the blood plasma. This relatively small amount of circulating cholesterol, however, is causally associated with atherosclerosis and coronary heart disease.

Understandably, there has been a great deal of research into the role of cholesterol in the body, and the understanding of how it is produced and what factors regulate the level of cholesterol in the blood. Dietary cholesterol is not an essential nutrient for humans &endash;&endash; the body is able to manufacture all it needs for itself. About 40 percent of the cholesterol that is ingested with food is absorbed into the blood stream; the rest is eliminated in bowel movements. Cholesterol in the diet is added to that already manufactured by the body. A high cholesterol diet, especially in a person whose hereditary tendency is to manufacture too much cholesterol, may lead to an excess of cholesterol in the body, which must be deposited, stored or excreted by the body. Most cholesterol is used by the liver to form bile salts, which then aid in the digestion and absorption of dietary fats. Some is removed by other body cells, which use cholesterol in membranous structures. The adrenal glands, ovaries, and testicles use cholesterol as a "building block" in the formation of cortisone, sex hormones, and other steroid compounds.

Cholesterol is transported in the blood by substances called lipoproteins. Lipoproteins are large molecules composed of varying amounts of specific proteins or peptides, combined with fat or fat like substances including cholesterol, cholesteryl esters, triglycerides, and phospholipids. Lipoproteins are classified according to their weight, or density. There are five major lipoprotein groups. These are: 1) Chylomicrons, 2) Very Low Density Lipoproteins (VLDL), 3) Intermediate Density Lipoproteins (IDL), 4) Low Density Lipoproteins (LDL), and 5) High Density Lipoproteins (HDL).

Chylomicrons are the primary transport system for triglycerides, and have relatively little to do with cholesterol. The IDL represents a mid way product in the conversion of VLDL to LDL. The lipoproteins are usually measured by the cholesterol attached to the lipoprotein molecule, and therefore the units of measurement most used in medicine are "HDL cholesterol", or "LDL cholesterol". The cholesterol