What is Cholesterol and how it affects me?

You've heard about cholesterol and know that you have to "watch it" to stay healthy. But what is cholesterol, and what exactly are you watching?

Cholesterol is a fatty substance that your body needs to function. In fact, it is essential for life. You need cholesterol to form cell membranes, many hormones and bile acids (which digest fat), to name just a few. Without cholesterol, you couldn't live. But, as is so often the case, too much cholesterol can hurt you.

When there's too much cholesterol in your blood, it can build up on the inside walls of your arteries. Over time, the cholesterol build-up, called plaque, can narrow the space for blood to flow through. This can happen in the arteries everywhere in the body but is most dangerous in the arteries that feed the heart and other vital organs.

When plaque build-up narrows the coronary arteries, which supply oxygen-rich blood to the heart, chest pain, shortness of breath and other symptoms of coronary heart disease occur. If a coronary artery is blocked completely, a heart attack results. Decreased blood flow to your brain can cause a stroke.

The higher your cholesterol levels, the greater your risk of heart disease and stroke. Given that heart disease is a top killer of men and women, this isn't a risk that you should ignore. However, eating in a heart-healthy way, being physically active and losing weight are things everyone can do to lower their cholesterol levels and their risks.

What's being measured when your cholesterol is checked? Why should some cholesterol referred to as "good," putting people at lower risk for heart disease, and another "bad"?

Types of cholesterol:
Your doctor may order tests to check your blood levels of cholesterol. Since cholesterol can't dissolve in the blood (it's not water-soluble), it doesn't circulate by itself. Instead, cholesterol travels through the bloodstream linked to "carriers" called lipoproteins.

There are three different types of lipoproteins. The two that are most important to remember in terms of your possible risk of heart disease are high-density lipoproteins (HDL) and low-density lipoproteins (LDL).

Cholesterol that is carried on low-density lipoproteins is called LDL cholesterol, the "bad" cholesterol. Higher levels of LDL cholesterol are associated with an increased risk for heart disease.

Cholesterol molecules that are linked to high-density lipoproteins are called HDL cholesterol, the "good" cholesterol. If you have higher levels of HDL cholesterol, you're at lower risk for heart disease.
Can't remember which cholesterol is "bad" and which is "good?"
Try this as a way to remind yourself: LDL cholesterol ("bad") is "low-down." HDL cholesterol ("good") comes "highly recommended."

"Good" and "bad" cholesterol:
Why should one type of cholesterol be labelled "good," putting people at lower risk for heart disease, and another labelled "bad?" Because LDL is the main carrier of cholesterol to body tissues, and HDL carries cholesterol away from body tissues.

When you have a lot of LDL cholesterol, there is a greater danger that too much may be deposited in artery walls, which may then become damaged. The arteries may develop a cholesterol and fatty build-up called a plaque on the inside, referred to as atherosclerosis, or "hardening of the arteries."

Cholesterol build-up can prevent adequate amounts of blood from flowing to the heart and may lead to complete blockage of an artery. It is the most common cause of CHD, and happens so slowly that you are not even aware of it. The higher your LDL cholesterol, the greater your chance of this build-up.

When you have higher levels of HDL in your blood, it means that more high-density lipoproteins carry cholesterol away from arterial walls and to the liver. The liver then eliminates the cholesterol from the body by excreting it in the bile. Clearly, the more this happens, the less likely is cholesterol to accumulate in arterial walls and worsen the progression of atherosclerosis.