WHAT IS CHOLESTEROL?
To understand high blood cholesterol (ko-LES-ter-ol), it helps to learn about cholesterol. Cholesterol is a waxy, fat-like substance that’s found in all cells of the body.
Your body needs some cholesterol to make hormones, vitamin D, and substances that help you digest foods. Your body makes all the cholesterol it needs. However, cholesterol also is found in some of the foods you eat.
Cholesterol travels through your bloodstream in small packages called lipoproteins (lip-o-PRO-teens). These packages are made of fat (lipid) on the inside and proteins on the outside.
Two kinds of lipoproteins carry cholesterol throughout your body: low-density lipoproteins (LDL) and high-density lipoproteins (HDL). Having healthy levels of both types of lipoproteins is important.
LDL cholesterol sometimes is called “bad” cholesterol. A high LDL level leads to a buildup of cholesterol in your arteries. (Arteries are blood vessels that carry blood from your heart to your body.)
HDL cholesterol sometimes is called “good” cholesterol. This is because it carries cholesterol from other parts of your body back to your liver. Your liver removes the cholesterol from your body.
WHAT IS HIGH BLOOD CHOLESTEROL?
High blood cholesterol is a condition in which you have too much cholesterol in your blood. By itself, the condition usually has no signs or symptoms. Thus, many people don’t know that their cholesterol levels are too high.
People who have high blood cholesterol have a greater chance of getting coronary heart disease, also called coronary artery disease. (In this article, the term “heart disease” refers to coronary heart disease.)
The higher the level of LDL cholesterol in your blood, the GREATER your chance is of getting heart disease. The higher the level of HDL cholesterol in your blood, the LOWER your chance is of getting heart disease.
Coronary heart disease is a condition in which plaque (plak) builds up inside the coronary (heart) arteries. Plaque is made up of cholesterol, fat, calcium, and other substances found in the blood. When plaque builds up in the arteries, the condition is called atherosclerosis (ATH-er-o-skler-O-sis).
Figure A shows the location of the heart in the body. Figure B shows a normal coronary artery with normal blood flow. The inset image shows a cross-section of a normal coronary artery. Figure C shows a coronary artery narrowed by plaque. The buildup of plaque limits the flow of oxygen-rich blood through the artery. The inset image shows a cross-section of the plaque-narrowed artery.
Over time, plaque hardens and narrows your coronary arteries. This limits the flow of oxygen-rich blood to the heart.
Eventually, an area of plaque can rupture (break open). This causes a blood clot to form on the surface of the plaque. If the clot becomes large enough, it can mostly or completely block blood flow through a coronary artery.
If the flow of oxygen-rich blood to your heart muscle is reduced or blocked, angina (an-JI-nuh or AN-juh-nuh) or a heart attack may occur.
Angina is chest pain or discomfort. It may feel like pressure or squeezing in your chest. The pain also may occur in your shoulders, arms, neck, jaw, or back. Angina pain may even feel like indigestion.
A heart attack occurs if the flow of oxygen-rich blood to a section of heart muscle is cut off. If blood flow isn’t restored quickly, the section of heart muscle begins to die. Without quick treatment, a heart attack can lead to serious problems or death.
Plaque also can build up in other arteries in your body, such as the arteries that bring oxygen-rich blood to your brain and limbs. This can lead to problems such as carotid artery disease, stroke, and peripheral arterial disease (P.A.D.).
where does cholesterol come from?
Cholesterol is a waxy substance that comes from two sources: your body and food. Your body, and especially your liver, makes all the cholesterol you need and circulates it through the blood. But cholesterol is also found in foods from animal sources, such as meat, poultry and full-fat dairy products. Your liver produces more cholesterol when you eat a diet high in saturated and trans fats.
Excess cholesterol can form plaque between layers of artery walls, making it harder for your heart to circulate blood. Plaque can break open and cause blood clots. If a clot blocks an artery that feeds the brain, it causes a stroke. If it blocks an artery that feeds the heart, it causes a heart attack. View an animation of cholesterol
There are two types of cholesterol: "good" and "bad." Too much of one type — or not enough of another — can put you at risk for coronary heart disease, heart attack or stroke. It's important to know the levels of cholesterol in your blood so that you and your doctor can determine the best strategy to lower your risk.
Making healthy eating choices and increasing exercise are important first steps in improving your cholesterol. For some people, cholesterol-lowering medication may also be needed to reduce the risk for heart attack and stroke. Use the information provided here to start a conversation with your doctor about how cholesterol affects your heart attack and stroke risk and what you can do to lower your risk.
Good Cholesterol vs. Bad Cholesterol
Cholesterol can't dissolve in the blood. It must be transported through your bloodstream by carriers called lipoproteins, which got their name because they’re made of fat (lipid) and proteins.
The two types of lipoproteins that carry cholesterol to and from cells are low-density lipoprotein, or LDL, and high-density lipoprotein, or HDL. LDL cholesterol and HDL cholesterol, along with one fifth of your triglyceride level, make up your total cholesterol count, which can be determined through a blood test.
LDL cholesterol is considered the “bad” cholesterol because it contributes to plaque, a thick, hard deposit that can clog arteries and make them less flexible. This condition is known as atherosclerosis. If a clot forms and blocks a narrowed artery, heart attack or stroke can result. Another condition called peripheral artery disease can develop when plaque buildup narrows an artery supplying blood to the legs.
HDL (Good) Cholesterol
HDL cholesterol is considered “good” cholesterol because it helps remove LDL cholesterol from the arteries. Experts believe HDL acts as a scavenger, carrying LDL cholesterol away from the arteries and back to the liver, where it is broken down and passed from the body. One-fourth to one-third of blood cholesterol is carried by HDL. A healthy level of HDL cholesterol may also protect against heart attack and stroke, while low levels of HDL cholesterol have been shown to increase the risk of heart disease.
Triglycerides
Triglycerides are another type of fat, and they’re used to store excess energy from your diet. High levels of triglycerides in the blood are associated with atherosclerosis. Elevated triglycerides can be caused by overweight and obesity, physical inactivity, cigarette smoking, excess alcohol consumption and a diet very high in carbohydrates (more than 60 percent of total calories). Underlying diseases or genetic disorders are sometimes the cause of high triglycerides. People with high triglycerides often have a high total cholesterol level, including a high LDL cholesterol (bad) level and a low HDL cholesterol (good) level. Many people with heart disease or diabetes also have high triglyceride levels.
Lp(a) Cholesterol
Lp(a) is a genetic variation of LDL (bad) cholesterol. A high level of Lp(a) is a significant risk factor for the premature development of fatty deposits in arteries. Lp(a) isn't fully understood, but it may interact with substances found in artery walls and contribute to the buildup of fatty deposits.
Cholesterol Levels
How’s your cholesterol? Time to get it checked!
Keeping your cholesterol levels healthy is a great way to keep your heart healthy – and lower your chances of getting heart disease or having a stroke.
But first, you have to know your cholesterol numbers.
The American Heart Association recommends all adults age 20 or older have their cholesterol, and other traditional risk factors, checked every four to six years.
Your test report will show your cholesterol levels in milligrams per deciliter of blood (mg/dL). Your total cholesterol and HDL (good) cholesterol are among numerous factors your doctor can use to predict your lifetime or 10-year risk for a heart attack or stroke.
Your test report will show your cholesterol levels in milligrams per deciliter of blood (mg/dL). To determine how your cholesterol levels affect your risk of heart disease, your doctor will also take into account other risk factors such as age, family history, smoking and high blood pressure.
A complete fasting lipoprotein profile will show the following for:
Total blood (or serum) cholesterol
Your total cholesterol score is calculated using the following equation: HDL + LDL + 20 percent of your triglyceride level. A total cholesterol score of less than 180 mg/dL is considered optimal.
A complete fasting lipoprotein profile will show the following for:
Total blood (or serum) cholesterol
Your total cholesterol score is calculated using the following equation: HDL + LDL + 20 percent of your triglyceride level. A total cholesterol score of less than 180 mg/dL is considered optimal.
HDL (good) cholesterol
With HDL cholesterol, higher levels are better. Low HDL cholesterol puts you at higher risk for heart disease. People with high blood triglycerides usually also have lower HDL cholesterol. Genetic factors, type 2 diabetes, and certain drugs, such as beta-blockers and anabolic steroids, also lower HDL cholesterol levels. Smoking, being overweight and being sedentary can all result in lower HDL cholesterol.
With HDL cholesterol, higher levels are better. Low HDL cholesterol puts you at higher risk for heart disease. People with high blood triglycerides usually also have lower HDL cholesterol. Genetic factors, type 2 diabetes, and certain drugs, such as beta-blockers and anabolic steroids, also lower HDL cholesterol levels. Smoking, being overweight and being sedentary can all result in lower HDL cholesterol.
LDL (bad) cholesterolA low LDL cholesterol level is considered good for your heart health. However, your LDL number should no longer be the main factor in guiding treatment to prevent heart attack and stroke, according to new guidelines from the American Heart Association. For patients taking statins, the guidelines say they no longer need to get LDL cholesterol levels down to a specific target number. A diet high in saturated and trans fats raises LDL cholesterol.
TriglyceridesTriglyceride is the most common type of fat in the body. Normal triglyceride levels vary by age and sex. A high triglyceride level combined with low HDL cholesterol or high LDL cholesterol is associated with atherosclerosis, the buildup of fatty deposits in artery walls that increases the risk for heart attack and stroke
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