Cholesterol
Cholesterol is a waxy, fat-like substance that occurs naturally in all parts of the
body, and your body needs it to function normally. If you have too much cholesterol in your
bloodstream, the excess is deposited in arteries, including the coronary arteries, where it
contributes to the narrowing and blockages that cause the signs and symptoms of heart disease.
Cholesterol is carried in small packages called lipoproteins, made of fat (lipid) on the
inside and proteins on the outside. Two kinds of lipoproteins carry cholesterol throughout your
body, and it's important to have healthy levels of both:
- Low-density lipoprotein (LDL) cholesterol is sometimes called bad cholesterol. High LDL cholesterol leads to a buildup of cholesterol in arteries, and the higher the LDL level in your blood, the greater the chance you have of getting heart disease.
- High-density lipoprotein (HDL) cholesterol is sometimes called good cholesterol. HDL carries cholesterol from other parts of your body back to your liver, and the liver removes the cholesterol from your body. The higher your HDL cholesterol level, the lower your chance of getting heart disease.
Too much cholesterol in the blood, or high blood cholesterol, can be serious. People
with high blood cholesterol have a greater chance of getting heart disease. High blood cholesterol
on its own does not cause symptoms, so many people are unaware that their cholesterol level is too
high. Cholesterol can build up on the walls of your arteries (blood vessels that carry blood from
the heart to other parts of the body). This buildup of cholesterol is called plaque, and, over
time, can cause narrowing of the arteries, a condition known as atherosclerosis or
hardening of the arteries.
Causes of high blood cholesterol
A variety of things can affect the cholesterol levels in your blood. Some of these things you can control and others you cannot. You can control:
- What you eat. Certain foods have types of fat that raise your cholesterol level. Saturated fat raises your low-density lipoprotein (LDL) cholesterol level more than anything else in your diet. Also raising cholesterol levels are trans fatty acids (trans fats), which are made when vegetable oil is hydrogenated to harden it. Cholesterol is found in foods that come from animal sources, such as egg yolks, meat, and cheese.
- Your weight. Being overweight tends to increase your LDL level, lower your high-density lipoprotein (HDL) level, and increase your total cholesterol level.
- Your activity. Lack of regular exercise can lead to weight gain, which could raise your LDL cholesterol level. Regular exercise can help you lose weight and lower your LDL level, as well as raise your HDL level.
Factors you cannot control include:
- Heredity. High blood cholesterol can run in families. An inherited genetic condition (familial hypercholesterolemia) results in very high LDL cholesterol levels. It begins at birth, and may result in a heart attack at an early age.
- Age and sex. Starting at puberty, men have lower levels of HDL than women. As women and men get older, their LDL cholesterol levels rise. Younger women have lower LDL cholesterol levels than men, but after age 55, women have higher levels than men.
Testing and prevention
High blood cholesterol is diagnosed by checking levels of cholesterol in your blood,
and a blood test called a lipoprotein profile measures your cholesterol levels. Most people
will need to avoid eating or drinking anything (i.e., fast) for 9 to 12 hours before taking the
test.
The lipoprotein profile will provide information about your:
- Total cholesterol
- Low-density lipoprotein (LDL) bad cholesterol (the main source of cholesterol buildup and blockage in the arteries)
- High-density lipoprotein (HDL) good cholesterol (the good cholesterol that helps keep cholesterol from building up in arteries)
- Triglycerides (another form of fat in your blood)
If it isn't possible to get a lipoprotein profile done, knowing your total
cholesterol and HDL cholesterol can give you a general idea about your cholesterol levels. Testing
for total and HDL cholesterol does not require fasting. If your total cholesterol is 200 mg/dL or
more, or if your HDL is less than 40 mg/dL, you will need to have a lipoprotein profile done.
Cholesterol levels are measured in milligrams (mg) of cholesterol per deciliter (dL) of
blood. See how your cholesterol numbers compare to the tables below.
|
Total Cholesterol Level |
Total Cholesterol Category |
|
Less than 200 mg/dL |
Desirable |
|
200–239 mg/dL |
Borderline high |
|
240 mg/dL and above |
High |
|
|
|
|
LDL Cholesterol Level |
LDL Cholesterol Category |
|
Less than 100 mg/dL |
Optimal |
|
100–129 mg/dL |
Near optimal/above optimal |
|
130–159 mg/dL |
Borderline high |
|
160–189 mg/dL |
High |
|
190 mg/dL and above |
Very high |
|
|
|
|
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 |
Triglycerides can also raise your risk for heart disease. If you have levels that are borderline high (150–199 mg/dL) or high (200 mg/dL or more), you may need treatment. Things that can increase triglyceride levels include being overweight, physical inactivity, smoking, excessive alcohol use, a high-carbohydrate diet, certain diseases and drugs, and genetic disorders.