Cholesterol facts

Cholesterol is an essential type of fat that is carried in the blood but too much of it is a risk factor for coronary artery disease. Managing your cholesterol by maintaining a healthy diet and lifestyle can help reduce your cholesterol levels.

What is cholesterol?

Cholesterol is an essential type of fat that is carried in the blood. All cells in the body need cholesterol for internal and external membranes. It is also needed to produce some hormones and for other functions. Too much cholesterol in the blood can damage your arteries and lead to heart disease.

About ¾ of the cholesterol in your bodies is made in the liver and the rest may come from the types of fats we eat. Your genes will also partly determine what your blood cholesterol levels are as will your diet and lifestyle. Cholesterol itself in food has only a very small effect on blood cholesterol. However eating too much saturated fat may lead to excess cholesterol in the blood stream.

Why is high cholesterol a problem?

High blood cholesterol is one risk factor for coronary artery disease (heart attacks and angina). If your cholesterol level is 6.5 mmol/L or greater your risk of heart disease is about four times greater than that of a person with a cholesterol level of 4 mmol/L. Not all people with high cholesterol levels get heart disease.

About 30 per cent of the community will die from heart disease and most of these will be over 65 years old. Heart disease usually takes 60-70 years to develop, but if you discover your cholesterol level is high you should see your doctor within the next 2-3 months, not necessarily tomorrow.

Other risk factors for heart disease include smoking, high blood pressure, type 2 diabetes and obesity. If you have more risk factors it is even more important to keep blood cholesterol levels in check and seek your doctor’s advice.

Cholesterol - the good and the bad

Cholesterol is carried in the blood stream in particles called lipoproteins. These are named according to how big they are:

  • The very large particles are called Very Low Density Lipoproteins (VLDL)  
  • The intermediate size ones are called Low Density Lipoprotein (LDL) and these particles cause heart disease 
  • The smallest particles are called High Density Lipoproteins (HDL) and these particles actually protect against heart disease.

What to do if your cholesterol level is high

The most effective way to lower your LDL cholesterol is to reduce the amount of saturated fat and follow a healthy diet. You could:

  • Limit cakes, biscuits, pastries 
  • Choose reduced fat milks 
  • Use polyunsaturated or monounsaturated margarine or oils instead of butter 
  • Choose lean cuts of meat and remove visible fat 
  • Remove fat from chicken  
  • Include more fish and beans in your meals 
  • Lose weight if overweight.

If you make a number of changes to your diet you can expect your cholesterol to fall by 10 per cent. About 15 per cent of people will see no change and another 15 per cent will see changes of 20-30 per cent. The CSIRO Healthy Heart Program has been shown to effectively lower LDL cholesterol levels by 15 per cent and includes comprehensive diet and lifestyle information for heart health.

How high is high cholesterol?

If your cholesterol level is between 5.5 and 6.5 your risk of heart disease is only increased by a small amount. Don’t panic but make a few moderate changes to your diet. However if you already have heart disease, or one of your parents developed heart disease at an early age, (less than 55 years of age) then you need to make bigger changes.

If your cholesterol level is higher than 6.5 then you need to make more changes.

If despite changes to your diet your cholesterol level remains above 6.5 you may need medication, especially if you have the other risk factors mentioned or you have a family history of heart disease – see your doctor.

What about triglycerides?

Triglycerides are a stored energy source. Most of the triglyceride in blood is found in the very large particles, the VLDL.

Under some circumstances high blood triglyceride can be a risk factor for heart disease. If your cholesterol is high, 6.5 and above is considered a high cholesterol level, and your HDL cholesterol is low (less than 0.9) then triglycerides can increase the risk of heart disease if they are greater than 1.7. 

Triglyceride levels greater than 10 can cause inflammation of the pancreas which is a very serious condition.

How can I lower my triglycerides?

To lower your triglycerides you should:

  • reduce excess weight, 
  • increase exercise, 
  • drink alcohol only in moderation as alcohol is very powerful at elevating triglyceride, and 
  • reduce the amount of refined starchy foods and sugary drinks in your diet. 

Your family doctor is best able to advise you if medications may be needed to control cholesterol, triglycerides and other risk factors.

At CSIRO we're carrying out research into how diet can improve heart health and reduce blood cholesterol levels. A high level of blood cholesterol is one of the risk factors for coronary artery disease (heart attacks and angina). If you're aged between 30-75 you might be eligible to participate in our cholesterol lowering study.

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