The low cholesterol diet is designed to lower an individual’s cholesterol level. Cholesterol is a waxy substance made by the liver and also acquired through diet. Cholesterol does not dissolve in blood. Instead it moves through the circulatory system in combination with carrier substances called lipoproteins. There are two types of carrier-cholesterol combinations, low-density lipoprotein (LDL) or “bad” cholesterol and high-density lipoprotein or “good” cholesterol.
LDL picks up cholesterol in the liver and carries it through the circulatory system. Most of the cholesterol in the body is LDL cholesterol. When too much LDL cholesterol is present, it begins to drop out of the blood and stick to the walls of the arteries. The arteries are blood vessels carrying blood away from the heart to other organs in the body. The coronary arteries are special arteries that supply blood to the heart. The sticky material on the artery walls is called cholesterol plaque. (It is different from dental plaque that accumulates on teeth.) Plaque can reduce the amount of blood flowing through the arteries and encourage blood clots to form. A heart attack occurs if the coronary arteries are blocked. A stroke occurs if arteries carrying blood to the brain are blocked.
Researchers believe that HDL works opposite LDL. HDL picks up cholesterol off the walls of the arteries and takes it back to the liver where it can be broken down and removed. This helps to keep the blood vessels open. Cholesterol can be measured by a simple blood test. To reduce the risk of cardiovascular disease, adults should keep their LDL cholesterol below 160 mg/ dL and their HDL cholesterol above 40 mg/dL.
Cholesterol is a necessary and important part of cell membranes. It also is converted into some types of steroid (sex) hormones. Cholesterol comes from two sources. The liver makes all the cholesterol the body needs from other nutrients. However, other animals also make cholesterol. When humans eat animal products, they take in more cholesterol. Cholesterol is found only in foods from animals, never in plant foods. The foods highest in cholesterol are organ meats such as liver, egg yolk (but not egg whites), whole-fat dairy products (butter, ice cream, whole milk), and marbled red meat. To reduce the risk of cardiovascular disease, adults should keep their consumption of cholesterol below 300 mg daily. In 2007, the average American man ate 337 mg of cholesterol daily and the average woman ate 217 mg.
Cholesterol and fats
There are three types of fats in food. Saturated fats are animal fats such as butter, the fats in milk and cream, bacon fat, the fat under the skin of chickens, lard, or the fat a piece of prime rib of beef. These fats are usually solid at room temperature and they are considered “bad” fats because they raise LDL cholesterol.
Unsaturated fats can be monounsaturated or polyunsaturated (This refers to one aspect of their chemical structure.) Monounsaturated fats are “good” fats that help lower cholesterol levels. Olive oil, canola oil, and peanut oil are high in monounsaturated fats. Corn oil, soybean oil, safflower oil, and sunflower oil are high in polyunsaturated fats. Polyunsaturated fats are not bad, they just are not as good as monounsaturated fats. Fish oils that are high in omega-3 fatty acids are polyunsaturated and are very beneficial in preventing heart disease.
Trans fat is made by a manufacturing process that creates hydrogenated or partially hydrogenated vegetable oils. Trans fat acts like saturated fat, raising the level of LDL cholesterol. It is found in some margarines and in many commercially baked and fried foods. Dietary Guidelines for Americans 2005 recommends that no more than 30% of an individual’s daily calories should come from fat, no more than 10% of calories should come from saturated fat, and people should consume as little trans fat as possible.
