Cholesterol overview

by | Heart Attacks and Strokes

When your blood cholesterol level is raised you may be at increased risk of heart attack, stroke and other cardiovascular diseases.

Some other risk factors for heart disease include diabetes, high blood pressure, having a family history of heart disease, increasing age and lifestyle factors such as smoking, obesity and lack of physical activity. Many people have more than one risk factor for heart disease and the level of risk increases with the number of risk factors.

It is, therefore, really important to know what your cholesterol levels are, and to keep them at a healthy level before you develop any problems.

What is cholesterol?

Cholesterol is a white, waxy substance which is a member of the lipid (fat) family. Without cholesterol our bodies could not manufacture a number of important hormones. It is also an essential component of the outer membrane of some cells.

Our liver manufactures most of our cholesterol, while the rest comes from the food we eat. The mix of fats in your diet (saturated versus unsaturated) has a greater effect on your blood cholesterol than the amount of cholesterol you eat.

‘Good’ and ‘bad’ cholesterol

Cholesterol and triglycerides (another important blood fat) are carried through the bloodstream by proteins called lipoproteins.

There are several types of lipoproteins, including:

  • Low-density lipoproteins (LDL) – LDL forms deposits in the wall of the arteries which turn into plaque, which can block the artery. It’s important to have low levels of LDL cholesterol. It is dubbed the ‘bad’ cholesterol.
  • High-density lipoproteins (HDL) –  HDL carries cholesterol back to the liver. You want to have high levels of HDL in your blood as a kind of cholesterol police, picking up the bad cholesterol. HDL-cholesterol is known as ‘good cholesterol’.
  • Very low-density lipoproteins (VLDL)  – VLDLs are made in the liver and their job is to carry fats called triglycerides to different parts of the body. Once the VLDLs drop off some of their fat load, they become LDLs, which carry the remaining cholesterol around the body.

Triglycerides are stored in your fat cells, to be used later when you need extra energy. They contribute to narrowing and hardening of the arteries and so raise the risk of heart disease, heart attack and stroke.


People with high LDL-cholesterol (bad cholesterol) generally have no symptoms. That’s why it is important to have a cholesterol test at regular intervals, so that if you have high cholesterol it can be picked up early.

Risk factors for high cholesterol

Some risk factors make it more likely that you will have high cholesterol:

  • Unhealthy diet: eating a diet that is too high in saturated and trans fats.
  • High BMI (Body Mass Index): having a high BMI puts you at risk of high cholesterol. Obesity is linked to higher LDL-cholesterol (‘bad’ cholesterol) and triglyceride levels and lower HDL-cholesterol (‘good’ cholesterol) levels. Find out your BMI, with our BMI calculator.
  • Diabetes: having diabetes increases the risk of high cholesterol.
  • Being inactive: exercise increases good cholesterol (HDL-cholesterol), which removes bad cholesterol from the body – so not getting enough physical activity can put you at risk of having high LDL (bad) cholesterol.
  • Genetic susceptibility: having a genetic (inherited) susceptibility to high blood cholesterol. If any member of your family has this condition, known as familial hypercholesterolaemia, it is important to have your cholesterol levels checked.


High blood cholesterol is a risk factor for cardiovascular diseases, such as heart attack and stroke. The excess cholesterol in the bloodstream causes fatty deposits (plaques) to gradually build up in the walls of the blood vessels (atherosclerosis), narrowing the blood vessels and making it harder for blood to flow through.

This can result in:

  • Angina – when the arteries supplying the heart are affected, angina can result.
  • Heart attack – If a plaque is damaged, then a blood clot will form and may plug the artery, or break off and block another artery downstream, causing a heart attack.
  • Stroke – a blood clot may block an artery to the brain, causing a stroke.
  • Peripheral arterial disease – if arteries in the legs are affected, you may have leg pain when you walk and other problems resulting from reduced blood supply to the legs. This is known as peripheral arterial disease

Tests and diagnosis

A cholesterol test is a simple blood test which measures the amount of cholesterol and other lipids you have in your bloodstream. It usually measures your total cholesterol, LDL cholesterol and HDL cholesterol levels, as well as your levels of triglycerides, another important fat in the blood. Your GP can organise the test. You normally have to fast for 12 hours before the test, but you can drink water during this time.

Your doctor will review your results in the light of any risk factors you have for heart disease, such as diabetes or smoking, and make individualised recommendations for your specific cholesterol targets. These may be different from those of other people.

Who should be tested?

Australian guidelines recommend that the following groups should have regular blood cholesterol and triglyceride tests:

  • All adults aged 45 years and above.
  • Aboriginal and Torres Strait Islander people from the age of 35 years – because they are at a higher risk of cardiovascular disease.

How often your cholesterol should be tested varies depending on your individual risk factors – and could be anything between every year to once every 5 years.


If your lipid results are abnormal, your doctor will suggest you make some changes to your diet and physical activity levels. In some people, lifestyle changes may be all that’s needed to bring cholesterol levels back into line, avoiding the need for medicines.

If lifestyle changes do not lower your cholesterol levels sufficiently, your doctor may suggest you take cholesterol-lowering medicines. However, this does not mean that you should abandon your lifestyle changes – they are still working to lower your risk of cardiovascular disease and may mean you take less medication than you would need otherwise.


Changes to diet and physical activity can play an important role in lowering cholesterol. By simply making changes to their diet and activity levels, some people can reduce their need for cholesterol-lowering medicines or avoid them entirely.

Saturated fat and trans fat

Too much saturated fat in the diet can lead to raised LDL (‘bad’) cholesterol levels, so it’s advisable to reduce your intake of saturated fat. Saturated fats are found in foods from animal sources, such as red meat, poultry fat, dairy products, and also in some plant oils, including coconut oil and palm oil.

Where possible, saturated fat should be replaced with heart-healthy unsaturated fats, such as olive oil, avocados, nuts and canola oil.

Trans fat is a type of unsaturated fat that acts like a saturated fat in the body. Trans fat is thought to be especially damaging to heart health because it increases your LDL (‘bad’) cholesterol level and decreases your HDL (‘good’) cholesterol level. Trans fats can be found in commercially baked cakes, biscuits, crackers and chips, but at the moment are not required to be listed on food labels in Australia. Foods labelled as containing “partially hydrogenated” vegetable oils contain trans fats.

Healthy diet

The Australian Dietary Guidelines provide general guidance for everyone, but if you follow them they will reduce your risk of heart disease. The Guidelines stress that healthy eating should be followed long term.

The Guidelines recommend Australians:

  • consume a variety of vegetables, fruit, wholegrain breads and cereals, and legumes (such as chickpeas, lentils and kidney beans);
  • eat 2-3 serves of oily fish per week;
  • replace full-fat dairy foods with low-fat dairy products;
  • choose lean meat and poultry;
  • do not add salt to cooking or meals;
  • avoid highly processed foods;
  • limit intake of foods containing saturated fat, added salt, added sugars and alcohol;
  • drink water.

Cholesterol-lowering foods

The Australian Dietary Guidelines form general advice for healthy eating which will result in a lowering of your risk of cardiovascular (heart, stroke and blood vessel) disease. But some of the following foods have been shown to have specific cholesterol-lowering properties.

  • Soluble fibre: Soluble fibre can reduce the absorption of cholesterol into your bloodstream. Examples of foods that contain soluble fibre are oats, lentils, kidney beans, barley, apples and pears and psyllium husks.
  • Monounsaturated fats such as avocado and olive oil have been shown to improve blood cholesterol.
  • Tree nuts (also monounsaturated fats) such as almonds, walnuts, hazelnuts, pecan nuts and pistachio nuts have been shown to improve cholesterol levels. Remember they are high in calories, so a handful a day is a good serve.
  • Fish contains polyunsaturated fatty acids, which may help heart health, and for this reason the Heart Foundation recommends that you eat 2 to 3 (preferably oily) fish meals per week. Fish oil supplements are often part of treatment to lower triglycerides.

Plant sterols (phytosterols) and plant stanols are compounds naturally occurring in plants, which have been shown to have LDL-cholesterol-lowering properties. The Heart Foundation recommends that adult Australians at high risk of cardiovascular disease consume 2-3 g of phytosterols per day. While a small amount of this can come from eating vegetable oils, seeds, legumes, and fruit and vegetables, to obtain a cholesterol-lowering effect, a person needs to eat some plant-sterol enriched foods, such as special margarines, breakfast cereals, reduced fat yoghurt, reduced fat milk, or lower fat cheese. These enriched foods can be found in most supermarkets. Plant sterols will be listed as an ingredient on the nutrition label. They should not be taken by pregnant women or children without seeking medical advice first. Taking more than the recommended amount will not lower your cholesterol any further than already achieved.

Healthy weight

Maintain a healthy weight or lose weight if you are overweight or obese. This means you should aim for a BMI (body mass index) between 18.5 and 24.9, however, even a weight loss of 5-10% of your original bodyweight can have a beneficial effect on your heart risk.

Losing weight has a favourable effect on heart disease risk by reducing LDL-cholesterol levels and triglycerides and increasing HDL (good) cholesterol for people who are overweight or obese.

Your doctor or a registered dietitian will be able to advise you on the best way to go about losing weight.

Physical activity

Being physically active can help increase your HDL (‘good’) cholesterol levels. This is a good thing as HDL takes ‘bad’ cholesterol (LDL-cholesterol) out of circulation and back to the liver.

  • Australian guidelines recommend 30 minutes of moderate intensity physical activity, such as brisk walking, on most or preferably every day. This can be accumulated in sessions of 10 minutes if it’s not possible to do it all at once. For moderate intensity activity, it should require effort, but you should still be able to have a conversation.
  • Increasing your physical activity can also help you lose weight, reduce your blood pressure, and improve both your cardiovascular and mental health.
  • Doing any physical activity is better than doing none.
  • Start with a comfortable level of activity, and build up gradually to the recommended amount. If you have any concerns about your health, get advice from your doctor first.
  • Try to build activity into your daily routine. For example, take the stairs instead of the lift, get off the train or bus one stop early, or walk in your lunch break at work.


If you drink alcohol, then drink only in moderation.

Alcohol seems to have a strong effect on raising triglyceride levels – a type of blood fat that increases the risk of heart, stroke and blood vessel disease by contributing to atherosclerosis (hardening or narrowing of the arteries). So if you have raised triglycerides it is recommended that you reduce your alcohol consumption. In any event, general Australian guidelines recommend limiting alcohol to 2 or fewer standard drinks per day.


Cigarettes damage your heart and blood vessels in several ways, including reducing the level of ‘good’ HDL cholesterol in the blood. The good news is that quitting smoking can improve your HDL levels and can halve your risk of heart disease within 12 months. There are various resources available to help you quit, including counselling, nicotine replacement therapy and other medicines. Your doctor will be able to advise you on the best resources to help you quit. You should also try to avoid exposure to second-hand smoke.


Some people need medicines in addition to lifestyle changes to bring their cholesterol levels down sufficiently. The type of medicine will depend on the results of your cholesterol test and your lipid profile.

Medicines commonly used for cholesterol/lipid lowering include:

  • Statins. These are used to reduce LDL-cholesterol (bad cholesterol) levels.
  • Ezetimibe. Can be used where statins are not suitable, or in addition to statins.
  • Cholestyramine and colestipol. Can be used where statins are not suitable, or in addition to statins.
  • Nicotinic acid. This is sometimes used in addition to other cholesterol-lowering medicines.

If you also have high triglycerides, your doctor may prescribe:

  • Fibrates, e.g. gemfibrozil and fenofibrate.
  • Fish oil.

According to Australian guidelines, people who need to be treated for high cholesterol (usually with statins) should generally aim for the following targets:

  • Total cholesterol – less than 4.0 mmol/L
  • LDL-cholesterol – less than 2.0 mmol/L
  • HDL-cholesterol – 1.0 mmol/L or more
  • Triglycerides – less than 2.0 mmol/L

People who have existing coronary heart disease may need to aim for an even lower LDL-cholesterol level of less than 1.8 mmol/L.

Remember, any lowering of either total cholesterol or LDL-cholesterol would be beneficial, even if you don’t reach the target levels.

Complementary therapies

Policosanol – a complementary therapy made from sugar cane – has been shown not to work in lowering cholesterol.


Following the same lifestyle advice as given above to lower cholesterol will also prevent most people from developing high cholesterol in the first place.

High cholesterol in children

Clinical signs of atherosclerosis — fatty build-ups in the arteries — can sometimes be seen as early as childhood. These fatty build-ups lead to a progressive narrowing and hardening of the arteries that can cause premature death or disability through heart attack or stroke.

The same risk factors that put adults at risk of developing atherosclerosis also put children at risk. These risk factors include high blood pressure, obesity, cigarette smoking, diabetes and high cholesterol. Some children will be more at risk because of a genetic (inherited) predisposition to high blood cholesterol.

High blood cholesterol levels in children make these fatty build-ups in the arteries more likely and there is evidence that the process of atherosclerosis can start in childhood and then progress slowly into adulthood.

Just as for adults, in children with high cholesterol, the higher the number of cardiovascular risk factors, the greater the risk of atherosclerosis, even though there may be no symptoms. For example, an overweight teenager who has raised cholesterol levels and smokes is likely to have more fatty deposits in their arteries than a similar aged non-smoker with a healthy body weight, who might also have an elevated cholesterol level.

Testing cholesterol in children

Most children do not need to be tested for blood cholesterol levels. However, children with diabetes or children who have a first-degree relative (parent, brother or sister) who has had coronary heart disease before the age of 60 may be tested to identify whether any steps should be taken to prevent future heart disease. Testing may also be recommended for children with a family history of high cholesterol. Testing may also be appropriate in other conditions such as liver or thyroid disease, or chronic kidney disease.

Testing is usually unnecessary for children under 2 years old, as they should not undergo dietary restrictions prior to that age because they have special nutritional needs for fat.

There is some evidence to show that testing of adolescent blood cholesterol levels can be inaccurate as the hormonal changes at puberty can mask high blood cholesterol levels. This means that there is a risk of getting a falsely low cholesterol reading, so teenagers at high risk of heart disease should be tested again after reaching young adulthood to get a more accurate result.

Healthy lifestyle

All children, but particularly those with elevated cholesterol levels, should be encouraged to lead an active lifestyle and follow a healthy diet. And, of course, smoking should be strongly discouraged.

A heart-healthy diet means eating less saturated fat, less total fat and less cholesterol. This can be achieved by eating lean meat, a wide variety of fruits, vegetables and wholegrain cereal products, using low-fat dairy products, eating fish 2-3 times a week, and limiting snack food, takeaway food, cakes and biscuits. Such a diet also has the added advantages of meeting the increased needs of children and teenagers for nutrients such as calcium, iron and zinc.

Research has also shown that cholesterol-lowering products enhanced with plant sterols can reduce cholesterol levels. In Australia, the foods that are approved for enrichment with plant sterols include margarine spreads, breakfast cereal, low-fat yogurt, low-fat milk, lower fat cheese and processed cheese. Most children do not need these products, but they may be useful in the diets of children with elevated cholesterol. However, studies have found that the cholesterol-lowering effect of these products is reduced in children compared with adults. Longer term studies are required to evaluate the safety of plant sterols in children.

As well as dietary restrictions, encouraging regular aerobic exercise and reducing the number of hours that children spend watching the television or using the computer can also help reduce their risk of cardiovascular disease.

Obese children and adolescents are more likely to have poorer health as adults, regardless of whether they are obese as an adult or not.

Cholesterol-lowering medicines for children

For some children, lifestyle measures alone will not be enough to reduce cholesterol levels. The choice to use medication to treat high cholesterol in children depends on various factors including age, cholesterol level and the presence or absence of other risk factors for cardiovascular disease. This decision is usually made by a cardiologist specialising in children.

A class of medicine called ‘statins’, used to treat high cholesterol in adults, can be used to treat elevated cholesterol in children. A child taking a statin medicine will need to be monitored for side effects and have blood tests periodically.

Another type of medicine that may be used is a bile-acid binding resin, but this type of medicine is often not tolerated well by children due to its side effects.

Other types of medicines used to treat high cholesterol in adults are undergoing further investigation to see whether they can be used safely in children.