Cholesterol for dummies

What is cholesterol?

Cholesterol is a type of fat which is carried around in your blood. Cholesterol is essential for your body – it is necessary for building cells and it helps to produce some hormones, such as oestrogen and testosterone. Unless you are severely malnourished, your body produces all the cholesterol it needs, so you do not need to eat foods containing cholesterol. There are two types of cholesterol – one good and one bad.

Where does cholesterol come from?

Cholesterol is found in animal products. This includes meat, dairy and eggs. There is no cholesterol in plant products. Although animal products contain cholesterol, it is not necessary to cut them out of your diet. You can safely eat up to six eggs per week, and the benefits you get from eating seafood far outweigh the cholesterol content.

What is bad cholesterol?

The scientific name for bad cholesterol is low density lipoprotein (LDL). It is often referred to as simply LDL. LDL is known as ‘bad’ cholesterol because having high levels of LDL is associated with an increased risk of coronary heart disease, stroke and peripheral artery disease. If there is too much bad cholesterol in your blood it ends up sticking to the walls of your arteries, which causes your artery walls to thicken and your arteries to narrow, decreasing the blood flow through the area. This process is called ‘atherosclerosis’.

What is good cholesterol?

The scientific name for good cholesterol is high density lipoprotein (HDL). It is often referred to as simply HDL. HDL is known as ‘good’ cholesterol because HDL extracts bad cholesterol from your artery walls and disposes of it through your liver. Good cholesterol helps to protect you against heart disease and stroke.

What is total cholesterol?

Total cholesterol is the sum of all the cholesterol in your blood. This includes HDL, LDL and triglycerides. Triglycerides are not technically a type of cholesterol, but they come with their own health risks, and are often associated with high levels of bad cholesterol.

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What is high cholesterol?

Having healthy levels of cholesterol is not just about having low levels of bad cholesterol. You need to make sure you have a healthy ratio of good to bad cholesterol. It might sound strange, but it is actually healthy to have high levels of good cholesterol. Having high levels of bad cholesterol and low levels of good cholesterol puts you at risk of atherosclerosis, or hardening and narrowing of the arteries. To protect you from heart disease and stroke, the most desirable ratio to have is a high level of good cholesterol and a low level of bad cholesterol.

How is cholesterol measured?

Your cholesterol levels can be measured with a simple blood test. The test results will give you four measures: your levels of good cholesterol, bad cholesterol, triglycerides and total cholesterol, which is the sum of all cholesterols and triglycerides. There are two systems of measuring cholesterol. They will give you different numbers, but they mean the same thing. InAustraliait is most common to see cholesterol measured in mmol/L, or millimoles per litre. You might also see cholesterol measured in mg/dl, or milligrams per decilitre, but this is more common in theUSA.

What do the numbers mean?

There is no measurable ‘healthy’ cholesterol level. Two people may have very different cholesterol levels and still be equally healthy. Having said that, health professionals do need a way to decide whether or not to take action. The following tables are a guide to what is generally considered to be ‘healthy’ cholesterol. The numbers may vary slightly depending on your information source.

Bad cholesterol

Australian (mmol/L)

USA (mg/dL)

Optimal if at high risk of heart disease

Below 1.8

Below 70


Below 2.6

Below 100

Slightly above optimal



Borderline high






Very high

5 and above

190 and above

Good cholesterol


Australian (mmol/L)

USA (mg/dL)


1.6 and above

60 and above



1–1.3 for men

1.3–1.5 for women

40–49 for men

50–59 for women



Below 1 for men

Below 1.3 for women

Below 40 for men

Below 50 for women

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How can I lower my bad cholesterol?

Lowering your bad cholesterol will decrease your risk of heart attacks and strokes. There are two ways to lower your bad cholesterol – through lifestyle changes and by taking medication. If your bad cholesterol levels are high you should start by losing any excess weight, exercising regularly (a brisk 30-minute walk most days of the week) and following a diet which is low in saturated fat and cholesterol – try changing to lean meats and low-fat dairy products. Quitting smoking is another good way to lower your bad cholesterol, and you should also limit your alcohol intake to two standard drinks per day.

There are also some foods which help to lower bad cholesterol. These include polyunsaturated oils, such as sunflower oil, oats and legumes.

If these lifestyle changes do not reduce your bad cholesterol to an acceptable level, your GP may prescribe medication. The most commonly used medications to lower bad cholesterol are called statins. If you are taking medication to lower your cholesterol you should also continue with the lifestyle changes, as the combination of the two will give you the best results.

How can I increase my good cholesterol?

Regular exercise, loss of excess weight and cessation of smoking will all increase your good cholesterol levels. There are also medications which can be used to bring your good cholesterol levels up, which can be prescribed by your GP if it becomes necessary.

How often should I get my cholesterol tested?

Everyone over the age of 20 should be getting their cholesterol tested every five years, and some experts recommend that men over 35 and women over 45 years of age get tested more frequently. If you are already having a yearly checkup then you may wish to ask for a cholesterol test at the same time.

To find out more you can read the CSIRO’s guide to The facts about cholesterol levels.