Updated 31 July 2014

Knowing cholesterol better

Good, bad, high density, low density? What is cholesterol exactly and why is it such a health issue?


What is cholesterol?

Cholesterol is a soft, waxy, fatty substance made naturally in the body, and we need a certain amount because it's vital for the formation of cell structures, hormones and substances that aid digestion.

The body makes most of the cholesterol it needs. But cholesterol is also found in some animal food products, and consuming too many can contribute to blood cholesterol becoming dangerously high.

Some people have a heriditary condition where their bodies make too much cholesterol.

“Good” and “bad” cholesterol

There are basically two kinds of cholesterol:

  1. “Good” or HDL cholesterol (the full term is High Density Lipoprotein cholesterol). HDL cholesterol is sometimes called “good” because it helps remove cholesterol from the arteries, the blood vessels that carry oxygen-rich blood from your heart to the body’s cells.
  2. “Bad” or LDL cholesterol (Low Density Lipoprotein cholesterol). LDL cholesterol is sometimes called “bad” because high levels are linked to build-up in your arteries.

A helpful way to remember the difference between HDL and LDL:

  • You want HDL cholesterol levels to be HIGH.
  • You want LDL cholesterol levels to be LOW.

Total cholesterol is a measure of the total amount of cholesterol in your blood, including both LDL and HDL cholesterol.

What is high cholesterol?

High cholesterol is when you have too much cholesterol in your blood. It may also be called high blood cholesterol, hypercholesterolemia or hyperlipidemia.

Your total cholesterol or LDL cholesterol may be too high, or your HDL cholesterol too low.

The most important effect of high cholesterol is that it can cause narrowing and blockages in the arteries.

Excess cholesterol, and other substances normally found in the blood like calcium and fat, can start to build up just under the lining of artery walls. 

The areas of the artery wall where cholesterol and other matter collects are called “plaques”.

The formation of plaques in the arteries is a condition called atherosclerosis, arteriosclerosis or “hardening of the arteries”.

How arteriosclerosis progresses

Over time, the plaques get harder and narrow the arteries further, limiting blood flow and damaging the artery wall. The rougher the plaques make the artery lining, the more likely substances like platelets, which make the blood sticky and promote clotting, will also get trapped there.

If narrowing occurs in the coronary arteries, which carry oxygen-rich blood to the heart muscle itself, the condition is called coronary artery disease or coronary heart disease, which raises risk for heart attack.

Coronary artery disease may cause angina: pain or a sensation of pressure in your chest. You may also feel angina pain in your arms, shoulders, neck, jaw or back; it may even feel like indigestion.

A section of plaque can break open, causing a blood clot to form: this can suddenly and dramatically block blood flow to a vital organ. Blood clots can also break free and travel in the body to cause blockages elsewhere.

A heart attack occurs if blood flow to part of the heart muscle suddenly becomes blocked. If you don't have emergency treatment to quickly get the blood flowing again, the section of heart muscle starved of oxygen-rich blood can die. A heart attack may be fatal.

Blockages in the arteries that supply the brain can lead to stroke, which damages the section of brain tissue deprived of oxygen-rich blood. Strokes are  also sometimes fatal.

- Olivia Rose-Innes, December 2012, Health24

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