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 usually a slow process that gets worse as you get older.

To understand what happens, think about how a clog forms in the pipe under a kitchen sink. Like the buildup of grease in the pipe, the buildup of cholesterol narrows your arteries and makes it harder for blood to flow through them. It reduces the amount of blood that gets to your body tissues, including your heart. This can lead to serious problems, including heart attack and stroke.

Your cholesterol is measured by a blood test:

- High cholesterol is 240 or above.
- Borderline-high is 200 to 239.
- Best is less than 200.

What are the different kinds of cholesterol?

- LDL is the "bad" cholesterol, the kind that can clog your arteries if you have too much of it. This is the cholesterol you need to lower, if you have high cholesterol.

- HDL is the "good" cholesterol. HDL helps clear fat from your blood. You want your HDL to be high. A high HDL level is linked to a lower risk of heart disease.

- Triglycerides are another type of fat in your blood. If you have high triglycerides and high LDL, your chances of having a heart attack are higher.

What are the symptoms?

High cholesterol doesn't make you feel sick. By the time you find out you have it, it may already be narrowing your arteries. So it is very important to start treatment even though you may feel fine.

What causes high cholesterol?  Many things can cause high cholesterol, including:

- The foods you eat. Eating too much saturated fat, trans fat, and cholesterol can raise your cholesterol.
- Being overweight.
- Being inactive.
- Age. Cholesterol starts to rise after age 20.
- Family history. If family members have or had high cholesterol, you may also have it.
- Overall health. Diseases such as hypothyroidism can raise cholesterol.

How is high cholesterol diagnosed?

You need a blood test to check your cholesterol. There are several kinds of tests:

- A fasting cholesterol test is the most complete test because it measures all of the fats in your blood, including LDL and HDL cholesterol and triglycerides.
- A direct LDL test measures your LDL level only.
- A simple cholesterol test can measure total cholesterol and HDL.

How is it treated?

If you have high cholesterol, you need treatment to lower your risk of heart attack and stroke. The two main treatments are lifestyle changes and medicine.