Many people associate cholesterol with bad health. The human body actually needs cholesterol, a type of fat, to produce hormones, provide structure to cell membranes and make bile acids necessary for the digestion of fats. To get to cells throughout the body, cholesterol travels through the blood. Because it is a fat, and therefore waxy, it cannot mix with blood without being packaged with specialized proteins known as lipoproteins. Different types of lipoprotein mean different types of cholesterol, some good and some bad.
LDL
LDL stands for low-density lipoprotein. This type of lipoprotein consists of a lot of fat and cholesterol in the center with a small amount of protein. LDL binds to cholesterol in the liver, which produces 75 percent of all the cholesterol in your body, and carries it through the blood to the cells for use. LDL serves a vital function, but when cholesterol levels increase beyond what the cells can use, the LDL builds up in the blood vessels. For this reason doctors refer to it as the "bad" cholesterol. The accumulation of cholesterol contributes to atherosclerosis--the formation of plaque and hardening of the arteries, and leads to heart disease. Doctors recommend keeping LDL cholesterol levels as low as possible, striving to stay below 100 milligrams per deciliter.
HDL
HDL, also known as high-density lipoprotein, differs in both structure and function from LDL. High-density lipoproteins are small, with very little fat and cholesterol in the center and a large amount of protein, therefore making them more dense. Because HDL can carry less cholesterol, it binds to only one-fourth to one-third of the cholesterol in the body, according to the American Heart Association. HDL picks up excess cholesterol from tissues and blood vessels and carries it back to the liver. The liver then breaks down the molecules and excretes the remnants out with the waste. Because HDL clears excess cholesterol from the body, doctors call it the "good" cholesterol. This makes higher levels of HDL more desirable. Men should try to maintain their HDL cholesterol level at 40 mg/dL or higher and women at 50 mg/dL or higher. HDL cholesterol levels above 60 mg/dL protect against heart disease.
Total
When doctors perform a nonfasting cholesterol test, they usually report back a total cholesterol level. The total cholesterol level takes into account the amount of HDL and LDL along with triglycerides and other lipids. Although LDL serves as an important factor in determining your risk for heart disease, knowing your total cholesterol can help you monitor your health. Optimally you should keep your total cholesterol under 200 mg/dL. Those with total cholesterol levels of 240 mg/dL or higher receive a diagnosis of high blood cholesterol and have twice the risk of developing heart disease than those with levels under 200 mg/dL, according to the Centers for Disease Control and Prevention.
Other
Very low-density lipoprotein is another type of cholesterol less talked about than LDL or HDL. VLDL contains the highest amount of fat, or triglycerides, of any of the lipoproteins. VLDL, similar to LDL, promotes the buildup of cholesterol along the walls of blood vessels. This classifies it as a "bad" cholesterol. A normal VLDL level ranges between 5 and 40 mg/dL, according to MedLinePlus. Higher levels are associated with an increased risk for heart disease. Triglycerides, another type of fat, differ from cholesterol but are a component of the lipoprotein and do impact the risk for heart disease. Doctors recommend maintaining your triglyceride levels to less than 150 mg/dL, according to MayoClinic.com.
References
- Centers for Disease Control and Prevention; America's Cholesterol Burden; February 2010
- American Heart Association; Good vs. Bad Cholesterol; July 2010
- National Heart Lung and Blood Institute; What is High Blood Cholesterol?; September 2008
- American Heart Association; What Your Cholesterol Levels Mean; February 2011
- MedLinePlus; VLDL Test; February 2011
- MayoClinic.com; Triglycerides -- Why do They Matter?; June 2010
