What Is Cholesterol?

To understand high blood cholesterol (ko-LES-ter-ol), it is important to know more about cholesterol.

• Cholesterol is a waxy, fat-like substance that is found in all cells of the body. Your body needs some cholesterol to work the right way. Your body makes all the cholesterol it needs.

• Cholesterol is also found in some of the foods you eat.

• Your body uses cholesterol to make hormones, vitamin D, and substances that help you digest foods.

Blood is watery, and cholesterol is fatty. Just like oil and water, the two do not mix. To travel in the bloodstream, cholesterol is carried in small packages called lipoproteins (lip-o-PRO-teens). The small packages are made of fat (lipid) on the inside and proteins on the outside. Two kinds of lipoproteins carry cholesterol throughout your body. It is 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. The higher the LDL level in your blood, the greater 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. The liver removes the cholesterol from your body. The higher your HDL cholesterol level, the lower your chance of getting heart disease.

What Is High Blood Cholesterol?

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 (plak). Over time, plaque can cause narrowing of the arteries. This is called atherosclerosis (ath-er-o-skler-O-sis), or hardening of the arteries.

Special arteries, called coronary arteries, bring blood to the heart. Narrowing of your coronary arteries due to plaque can stop or slow down the flow of blood to your heart. When the arteries narrow, the amount of oxygen-rich blood is decreased. This is called coronary artery disease (CAD). Large plaque areas can lead to chest pain called angina (an-JI-nuh or AN-juh-nuh). Angina happens when the heart does not receive enough oxygen-rich blood. Angina is a common symptom of CAD.

Some plaques have a thin covering and burst (rupture), releasing fat and cholesterol into the bloodstream. The release of fat and cholesterol may cause your blood to clot. A clot can block the flow of blood. This blockage can cause angina or a heart attack.

Lowering your cholesterol level decreases your chance for having a plaque burst and cause a heart attack. Lowering cholesterol may also slow down, reduce, or even stop plaque from building up.

Plaque and resulting health problems can also occur in arteries elsewhere in the body.

What Causes 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.

  • Trans fatty acids (trans fats) are made when vegetable oil is hydrogenated to harden it. Trans fatty acids also raise cholesterol levels.

  • Cholesterol is found in foods that come from animal sources, for example, 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. It can also help you raise your HDL level.

You cannot control:

• 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.

What Are The Signs and Symptoms of High Blood Cholesterol?

There are usually no signs or symptoms of high blood cholesterol. Many people don't know that their cholesterol level is too high.  Everyone age 20 and older should have their cholesterol levels checked at least once every 5 years. 

How Is High Blood Cholesterol Diagnosed?

High blood cholesterol is diagnosed by checking levels of cholesterol in your blood. It is best to have a blood test called a lipoprotein profile to measure your cholesterol levels. Most people will need to not eat or drink anything (fast) for 9 to 12 hours before taking the test.

The lipoprotein profile will give 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 is not 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.

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:

• Overweight

• Physical inactivity

• Cigarette smoking

• Excessive alcohol use

• Very high carbohydrate diet

• Certain diseases and drugs

• Genetic disorders

How Is High Blood Cholesterol Treated?

The main goal of cholesterol-lowering treatment is to lower your low-density lipoprotein (LDL) level enough to reduce your risk of having a heart attack or diseases caused by hardening of the arteries. In general, the higher your LDL level and the more risk factors you have, the greater your chances of developing heart disease or having a heart attack. (A risk factor is a condition that increases your chance of getting a disease.) Some people are at high risk for heart attack because they already have heart disease. Other people are at high risk for developing heart disease because they have diabetes or a combination of risk factors for heart disease. 

Check the list to see how many of the following risk factors you have. These are the risk factors that affect your LDL goal:

• Cigarette smoking

• High blood pressure (140/90 mg/dL or higher), or if you are on blood pressure medicine

• Low high-density lipoprotein (HDL) cholesterol (less than 40 mg/dL)

• Family history of early heart disease (heart disease in father or brother before age 55; heart disease in mother or sister before age 65)

• Age (men 45 years or older; women 55 years or older)

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