To help you understand high blood cholesterol, the National Heart, Lung, and Blood Institute offers this explanation on what it is and why it can be dangerous to your health.
Cholesterol is a waxy, fat-like substance that is found in all cells of the body. Your body needs some cholesterol to work the right way and makes all the cholesterol you need. Cholesterol is also found in some of the foods you eat.
You use cholesterol to make hormones, Vitamin D, and substances that help you digest foods.
Blood is watery and cholesterol is fatty. Just like water and oil, the two do not mix. So, in order to travel in the bloodstream, cholesterol is carried in small packages called lipoproteins. The small packages are made of fat (lipid) on the inside and proteins on the outside.
Two kinds of lipoproteins carry cholesterol throughout your body. It is important to have healthy levels of both: LDL (low-density lipoprotein) cholesterol, sometimes called "bad" cholesterol, and HDL (high-density lipoprotein), sometimes called "good" cholesterol.
High LDL cholesterol leads to a buildup of cholesterol in arteries. The higher the LDL level in your blood, the greater chance you have of getting heart disease.
HDL carries cholesterol from other parts of your body back to your liver. The liver removes the cholesterol from your body. The higher your HDL cholesterol level, the lower your chance of getting heart disease.
Too much cholesterol in your blood can build up in the walls of your arteries (blood vessels that carry blood from the heart to other parts of the body). This buildup of cholesterol is called plaque.. Over time, plaque can cause narrowing of the arteries. This is called atherosclerosis or hardening of the arteries.
Special arteries, called coronary arteries, bring blood to the heart. Narrowing of your coronary arteries due to plaque can stop or slow down the flow of blood to your heart. When the arteries narrow, the amount of oxygen-carrying blood is decreased. This is called coronary artery disease (CAD). Large plaque areas can lead to chest pain called angina. Angina happens when the heart does not receive enough blood and the oxygen it carries. Angina is a common sign of CAD.
Some plaques have a thin covering and burst (rupture), releasing fat and cholesterol into the bloodstream. The release of fat and cholesterol may cause your blood to clot. A clot can block the flow of blood. This blockage can cause angina or a heart attack.
Lowering your cholesterol level decreases your chance of having a plaque burst and cause a heart attack. Lowering cholesterol may also slow down, reduce, or even stop plaque from building up.
Plaque and resulting health problems can also occur in arteries elsewhere in the body.