Cholesterol is a waxy, fat-like substance that's found in all the cells in your 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. Cholesterol is also found in foods from animal sources, such as egg yolks, meat, and cheese.
If you have too much cholesterol in your blood, it can combine with other substances in the blood to form plaque. Plaque sticks to the walls of your arteries. This buildup of plaque is known as atherosclerosis. It can lead to coronary artery disease, where your coronary arteries become narrow or even blocked.
High cholesterol has no obvious symptoms. A blood test is the only way to detect if you have it.
Having high level of cholesterol in your body can increase your risk for conditions that do have symptoms, including:
Cholesterol is carried through your blood system, attached to proteins. This combination of proteins and cholesterol is called a lipoprotein.
Based on what the lipoprotein carries, there are different types of cholesterol:
Low-density lipoprotein (LDL). LDL, or "bad" cholesterol, transports cholesterol particles throughout your body. LDL cholesterol builds up in the walls of your arteries, making them hard and narrow.
High-density lipoprotein (HDL). HDL, or "good" cholesterol, picks up excess cholesterol and takes it back to your liver.
A lipid profile also typically measures triglycerides, a type of fat in the blood. Having a high triglyceride level can also increase your risk of heart disease.
Cholesterol causes you can control:
Cholesterol causes beyond your control (that may play a part):
Your body genetic makeup keeps cells from removing LDL cholesterol from your bloodstream efficiently or cause your liver to produce too much cholesterol.
When to see a doctor
Ask your doctor if you should have a cholesterol test. Children and young adults with no risk factors for heart disease are usually tested once between the ages of 9 and 11 and again between the ages of 17 and 19.
Retesting for adults with no risk factors for heart disease is usually done every five years.
If your test results aren't within desirable ranges, your doctor might recommend more frequent measurements.
If you have a family history of high cholesterol, heart disease or other risk factors, such as smoking, diabetes or high blood pressure, your doctor might also suggest more frequent tests in such conditions.
Factors that can increase your risk of bad cholesterol include:
Poor diet, consuming saturated fat, found in animal products, and trans fats, found in some commercially baked cookies and crackers and microwave popcorn, can raise your cholesterol level.
Foods that are high in cholesterol, such as red meat and full-fat dairy products, will also increase your cholesterol.
Obesity, having a body mass index (BMI) of 30 or greater puts you at risk of high cholesterol.
Lack of exercise, exercise helps boost your body's HDL, or "good," cholesterol while increasing the size of the particles that make up your LDL, or "bad," cholesterol, which makes it less harmful.
Smoking, cigarette smoking damages the walls of your blood vessels, making them more prone to accumulate fatty deposits. Smoking might also lower your level of HDL, or "good," cholesterol.
Age, because your body's chemistry changes as you age, your risk of high cholesterol climbs. For instance, as you age, your liver becomes less able to remove LDL cholesterol.
Diabetes, high blood sugar contributes to higher levels of a dangerous cholesterol called very-low-density lipoprotein (VLDL) and lower HDL cholesterol. High blood sugar also damages the lining of your arteries.
High cholesterol can cause a dangerous accumulation of cholesterol and other deposits on the walls of your arteries (atherosclerosis). These deposits (plaques) can reduce blood flow through your arteries, which can cause serious complications, including:
Chest pain, if the arteries that supply your heart with blood (coronary arteries) are affected, you might have chest pain (angina) and other symptoms of coronary artery disease.
Heart attack, if plaques tear or rupture, a blood clot can form at the plaque-rupture site, blocking the flow of blood or breaking free and plugging an artery downstream. If blood flow to part of your heart stops, you'll have a heart attack.
Stroke, similar to a heart attack, a stroke occurs when a blood clot blocks blood flow to part of your brain.