Cholesterol describes a type of fat produced by the liver and other cells of the body. Although doctors bombard you with warnings to stay away from fats and to keep cholesterol levels low, the body actually needs fat and cholesterol in order to function effectively. In reality several types of dietary fats exist and only some of them adversely affect cholesterol levels. In addition, the body contains different types of cholesterol including LDL and HDL.
Lipoproteins
Cells in the body produce approximately 75 percent of the cholesterol found in the blood, according to the American Heart Association. In order for cholesterol to move between cells, it must be transported by the blood. Because cholesterol is a waxy fat-like substance it cannot dissolve in the water-based blood. Therefore specialized proteins, known as lipoproteins, carry the cholesterol through the bloodstream.
LDL
LDL is the abbreviation for one of the specialized lipoproteins known as low-density lipoprotein. Low-density lipoproteins bind the majority of the cholesterol in the body so as the amount of cholesterol increases the LDL also increases. Because LDL remains in the bloodstream, as cholesterol levels and therefore LDL levels increase the amount of cholesterol in the blood vessels also increases. LDL can therefore accumulate along the walls of the blood vessels restricting the flow of blood and contributing to heart disease. Doctors therefore refer to LDL as the "bad" cholesterol.
HDL
Some cholesterol binds to the other type of lipoprotein known as high-density lipoprotein, or HDL. HDL only accounts for approximately one-third to one-fourth of all the cholesterol in the body, according to the American Heart Association. Because HDL carries cholesterol to the liver which breaks it down and removes it from the body doctors refer to it as the "good" cholesterol.
LDL and Diet
In addition to the cholesterol produced by cells in the body, diet contributes approximately 25 percent of the total cholesterol. Therefore the foods we eat can significantly affect the total cholesterol levels which affect the amount of LDL. Eating foods that contain unsaturated fats, which includes polyunsaturated and monounsaturated fats, actually helps to lower LDL cholesterol levels and increase HDL cholesterol levels. The bad fats, including saturated fats found in animal products and trans fats created through a process of hydrogenation, increase LDL levels. Trans fats, the worst type of fat as reported by the Harvard School of Public Health, also reduces HDL levels.
Healthy LDL Levels
As LDL levels increase the cholesterol accumulates in the blood vessels forming a substance known as plaque which leads to a condition known as atherosclerosis -- the formation of scar tissue on the artery walls. To reduce the risk of atherosclerosis, and therefore the risk of developing heart disease, doctors recommend keeping LDL levels at less than 100 mg/dL. Knowing your total cholesterol level can help monitor LDL levels. To maintain a healthy heart, keep the total cholesterol levels at 200 mg/dL or less.
