Cholesterol is a type of fat (lipid) in your blood. Your cells need cholesterol, and your body makes all it needs. But you also get cholesterol from the food you eat.

If you have too much cholesterol, it starts to build up in your arteries. (Arteries are the blood vessels that carry blood away from the heart.) This is called hardening of the arteries, or atherosclerosis camera.gif. It is the starting point for some heart and blood flow problems. The buildup can narrow the arteries and make it harder for blood to flow through them. The buildup can also lead to dangerous blood clots and inflammation that can cause heart attacks and strokes.

There are different types of cholesterol.

LDL is the "bad" cholesterol. It's the kind that can raise your risk of heart disease, heart attack, and stroke.
HDL is the "good" cholesterol. It's the kind that is linked to a lower risk of heart disease, heart attack, and stroke.

What you eat. Eating too much saturated fat, trans fat, and cholesterol can cause high cholesterol.
Saturated fat and cholesterol are in foods that come from animals, such as meats, whole milk, egg yolks, butter, and cheese.
Trans fat is found in fried foods and packaged foods, such as cookies, crackers, and chips.
Your weight. Being overweight may increase triglycerides and decrease HDL (good cholesterol).
Your activity level. Lack of physical activity can lower your HDL.
Your age and gender. After you reach age 20, your cholesterol naturally begins to rise.
In men, cholesterol generally levels off after age 50.
In women, it stays fairly low until menopause. Then it rises to about the same level as in men.
Some diseases. Certain diseases may raise your risk of high cholesterol. These include hypothyroidism, chronic kidney disease, and some types of liver disease.
Your family history. High cholesterol may run in your family. If family members have or had high cholesterol, you may also have it.
Cigarette smoking. Smoking can lower your HDL cholesterol.
Certain medicines. Some medicines can raise triglyceride levels and lower HDL (good) cholesterol levels. These medicines include thiazide diuretics, beta-blockers, estrogen, and corticosteroids.

High cholesterol does not cause symptoms. It is usually found during a blood test that measures cholesterol levels.

Some people with rare lipid disorders may have symptoms such as bumps in the skin, hands, or feet, which are caused by deposits of extra cholesterol and other types of fat.

Some people need to take medicines to reduce their risk of a heart attack or stroke. Your doctor may recommend that you take medicines called statins.

You and your doctor can work together to decide what treatment is best for you. Your doctor may recommend that you take statins if the benefits outweigh the risks.

Statins are always used along with a plan for a heart-healthy lifestyle, not instead of it.

Other medicines can improve cholesterol levels, but they have not been proven to lower the risk of a heart attack or a stroke. Your doctor may recommend these medicines if there is a reason you can't take a statin. These medicines include bile acid sequestrants, cholesterol absorption inhibitors, fibric acid derivatives, and nicotinic acid (niacin).

A heart-healthy lifestyle can help you prevent heart and blood flow problems, such as heart attacks and strokes.

This lifestyle includes:

Eating a heart-healthy diet that is rich in fruits, vegetables, whole grains, fish, and low-fat or nonfat dairy foods.
Being active on most, if not all, days of the week.
Losing weight if you need to, and staying at a healthy weight.
Not smoking.
Heart-healthy diets include the DASH diet, the Mediterranean diet and the American Heart Association diet recommendations. This chart compares several heart-healthy diets(What is a PDF document?).

Remember that cholesterol is just one of the things that increase your risk for heart attack and stroke. Controlling other health problems, such as high blood pressure and diabetes, can also help reduce your overall risk.