Cholesterol is a waxy substance found in your blood. Your body needs cholesterol to build healthy cells, but high levels of cholesterol can increase your risk of heart disease.
With high cholesterol, you can develop fatty deposits in your blood vessels. Eventually, these deposits grow, making it difficult for enough blood to flow through your arteries. Sometimes, those deposits can break suddenly and form a clot that causes a heart attack or stroke.
High cholesterol can be inherited, but it's often the result of unhealthy lifestyle choices, which make it preventable and treatable. A healthy diet, regular exercise and sometimes medication can help reduce high cholesterol.
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High cholesterol has no symptoms. A blood test is the only way to detect if you have it.
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. Your doctor might also suggest more-frequent tests if you have a family history of high cholesterol, heart disease or other risk factors, such as smoking, diabetes or high blood pressure.
Cholesterol is carried through your blood, attached to proteins. This combination of proteins and cholesterol is called a lipoprotein. There are different types of cholesterol, based on what the lipoprotein carries. They are:
- 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.
Factors you can control — such as inactivity, obesity and an unhealthy diet — contribute to high cholesterol and low HDL cholesterol. Factors beyond your control might play a role, too. For example, your genetic makeup might keep cells from removing LDL cholesterol from your blood efficiently or cause your liver to produce too much cholesterol.
Factors that can increase your risk of bad cholesterol include:
- Poor diet. Eating 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.
Development of atherosclerosis
If you have too many cholesterol particles in your blood, cholesterol may accumulate on your artery walls. Eventually, deposits called plaque may form. The deposits may narrow — or even block — your arteries. The plaque can also rupture, causing a blood clot to form.
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 complications, such as:
- 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.
The same heart-healthy lifestyle changes that can lower your cholesterol can help prevent you from having high cholesterol in the first place. To help prevent high cholesterol, you can:
- Eat a low-salt diet that emphasizes fruits, vegetables and whole grains
- Limit the amount of animal fats and use good fats in moderation
- Lose extra pounds and maintain a healthy weight
- Quit smoking
- Exercise on most days of the week for at least 30 minutes
- Drink alcohol in moderation, if at all
- Manage stress