High density lipoprotein, or HDL for short, is a substance found within the body that is used to transport
cholesterol. It is also referred to as HDL cholesterol or "good" cholesterol.
Understanding Cholesterol and Lipoproteins
In order to better understand HDL, it may be helpful to understand a little more about cholesterol and lipoproteins.
Cholesterol is a soft, waxy substance found in all of your body's cells. Your body needs this cholesterol in order to work properly. However, in order to get to all of your cells, cholesterol needs to travel through the bloodstream. But because cholesterol is a fat, it separates from the blood similar to the way that oil separates from water.
To keep this from happening, proteins form a shell around the cholesterol, making a "cholesterol complex." It is then released into the bloodstream and travels to where it needs to go.
A protein that is linked to cholesterol to form this cholesterol complex is called a "lipoprotein." There are several different types of lipoproteins. When talking about cholesterol, though, we normally talk about two types. One is good and the other
can be bad. You have probably heard about "good" cholesterol and "bad" cholesterol. What is interesting is that for both
good cholesterol (HDL) and
bad cholesterol (
LDL), the cholesterol is the same; what makes it good or bad is the type of lipoprotein that it is inside.
HDL: The "Good" Cholesterol
HDL
cholesterol is "good" because it picks up the extra cholesterol that was dropped off by the
LDLs and brings it to your liver. This way, your liver can repackage it to use it later or simply get rid of it. Because HDL cholesterol removes excess "bad" cholesterol (LDL), it is good to have high levels of HDL in your system and low levels of LDL. Think of "H" for "high" to help you remember this. And "L" stands for low, which is a way to remember that you want low levels of LDL.
Understanding Your HDL Numbers
Because HDL helps remove cholesterol from the blood, it can help keep cholesterol from building up in the walls of the arteries (known as
plaque). Plaque buildup can lead to a condition called
atherosclerosis, which is narrowing of the arteries. Narrowing of the arteries can lead to
heart disease (see Cholesterol and Heart Disease).
This explains why if your HDL
cholesterol level is low (below 40 mg/dL), you are at substantially higher risk for
heart disease. The higher your level, the better off you are, as the following table shows.
|
HDL Cholesterol Level
|
HDL Cholesterol Category
|
|
Less than 40 mg/dL
|
A major risk factor for heart disease
|
|
40–59 mg/dL
|
The higher, the better
|
|
60 mg/dL and above
|
Considered protective against heart disease
|
(Cholesterol levels are measured in milligrams [mg] of cholesterol per deciliter [dL] of blood.)
The average HDL cholesterol level for men is about 45 mg/dL; for women, it is about 55 mg/dL.
There are several ways for people with low HDL to raise it. Lifestyle changes that are known to
increase HDL include:
- Losing weight
- Quitting smoking
- Moderate exercise
- Moderate alcohol use, especially red wine.
Certain medications can also raise these levels, including:
