What are the different types of cholesterol?

There are three kinds of cholesterol. I like to categorize them according to an old cowboy film: The Good, the Bad and the Ugly. GOOD=HDL (high-density lipoprotein), BAD=LDL (low-density lipoprotein), UGLY=triglycerides. Here's LDL's role: it takes cholesterol from the liver and carries it to our tissues and organs. Plaques are formed by LDL. The good cholesterol, HDL, takes cholesterol from our veins and carries it to the liver where it is discarded through our intestines. HDL's job prevents the formation of plaques. Triglycerides are another type of fat found in our blood. If they exceed normal levels, they are also harmful, although not as harmful as LDL. Triglyceride levels can be high in people who have poorly managed diabetes, are taking certain medications and/or are obese.

Cholesterol and triglycerides are the two major forms of fat that circulate in the blood, and together they are referred to as lipids. You know that oil and water don't mix, and so it is with cholesterol or triglycerides and blood. These fats don't dissolve in the blood, but are packaged into particles along with special proteins. There are different types of particles, and each has a different metabolic part to play. The major particles are termed high-density lipoprotein, or HDL; low-density lipoprotein, or LDL; and very-low-density lipoprotein, or VLDL.

All cholesterol is chemically the same, but when it's packaged in one type of particle it does one thing, and when packaged in a different kind of particle it does another. HDL particles help remove cholesterol from the linings of blood vessels, so the higher the HDL cholesterol level, the lower the risk of heart disease. HDL is usually termed "good" cholesterol for this reason. LDL particles put more cholesterol into the plaques lining arteries, so the higher the LDL cholesterol level, the greater the risk of heart disease. LDL cholesterol is therefore called "bad" cholesterol. VLDL particles contain mostly triglycerides. HDL cholesterol levels of 40 mg/dL or more for a man and 50 or more for a woman are generally considered normal, but the higher you go the better off you are. Similarly, LDL cholesterol levels should be less than 100 to be normal, but there is evidence that even lower values help reduce your risk of heart disease.

Some cholesterol comes from the foods you eat, but most is made by your liver and comes in two basic forms: low-density lipoprotein (LDL) or high-density lipoprotein (HDL). LDL particles carry and deliver cholesterol to cells throughout the body; HDL particles mop up excess cholesterol and carry it back to the liver for disposal. If the body produces more LDL cholesterol than the cells can absorb, the excess settles in artery walls and contributes to atherosclerotic plaque. That's why LDL is often called "bad" cholesterol and HDL "good" cholesterol -- even though the body needs both.