Cholesterol

What is cholesterol?

Cholesterol is a type of fat that is part of all animal cells.

It is essential for many of the body’s metabolic processes, including the production of hormones, bile and vitamin D.

Cholesterol is important

Cholesterol is produced by the liver and also made by most cells in the body. It is carried around in the blood by little ‘couriers’ called lipoproteins.

We need a small amount of blood cholesterol because the body uses it to:

• build the structure of cell membranes
• make hormones like oestrogen, testosterone and adrenal hormones
• help your metabolism work efficiently, for example, cholesterol is essential for your body to produce vitamin D
• produce bile acids, which help the body digest fat and absorb important nutrients.

How cholesterol moves around the body

Cholesterol is a waxy fat-like substance. It is carried around the body by 2 key transport systems in the blood, which include:

• Low-density lipoprotein (LDL) cholesterol – carries most of the cholesterol that is delivered to cells. It is called the ‘bad’ cholesterol because when its level in the bloodstream is high, it can lead to blockages that prevent blood flow to your heart.
• High-density lipoprotein (HDL) cholesterol – is called the ‘good’ cholesterol, because it helps remove excess cholesterol out of the cells, including cells in the arteries.

How to check your cholesterol levels

Your doctor can check your cholesterol levels through a blood test.

The blood test measures:

• total cholesterol
• HDL cholesterol
• LDL cholesterol
• triglycerides, another type of fat in the blood.

You should have your cholesterol checked every 5 years from the age of 45 years, or from 18 years if you are an Aboriginal and Torres Strait Islander.

If you have a family history of high cholesterol, speak to your doctor about your heart attack risk.

There are no symptoms for high cholesterol.

Safe blood cholesterol levels

Many factors influence your cholesterol levels.

Total cholesterol levels should be lower than 5.5 mmol/L, if you have no other risk factors.

If you have cardiovascular risk factors such as high blood pressure, pre-existing cardiovascular (heart) disease or diabetes, or you smoke, the aim for LDL cholesterol levels would be less than 2 mmol/L.

Approximately half of all adult Australians have a blood cholesterol level above 5 mmol/L. This makes high blood cholesterol a major health concern in Australia.

There are guidelines for target cholesterol levels in different people. Your doctor will talk to you about your cholesterol test results and how to lower cholesterol and reduce your risk of heart disease.

Risk factors for high cholesterol

There is no single cause of high cholesterol, but there are some controllable risk factors (smoking) and non-controllable risk factors (age).

Risk factors for high cholesterol include:

• age
• smoking
• lack of physical activity
• overweight or obesity
• family history
• unhealthy diet.

Effects of high cholesterol levels

The liver is the main processing centre for cholesterol and dietary fat. When we eat animal fats, the liver transports the fat, together with cholesterol in the form of lipoproteins, into our bloodstream.

Too much cholesterol circulating within LDL in our bloodstream leads to fatty deposits developing in the arteries. This causes the vessels to narrow and they can eventually become blocked. This can lead to heart disease and stroke.

Foods that contain cholesterol

Research has shown that cholesterol in food has a neutral relationship with blood cholesterol levels.

For those not at high risk of cardiovascular disease or diabetes or who have not previously had LDL lowering treatment, there is no limit to the amount of cholesterol which can be consumed in foods such as eggs and animal products. However, if you do have these risk factors a maximum of 7 eggs per week is advised.

Dietary tips to avoid cholesterol

Following a healthy diet and lifestyle can help to lower your cholesterol levels over time, including:

• Increase the amount and variety of fresh fruit, vegetables and wholegrain foods you have each day.
• Choose unflavoured and low or reduced-fat milk, yoghurt and other dairy products, or have ‘added calcium’ (at least 100 mg/100mL) alternatives. People with high cholesterol should choose reduced fat varieties.
• Choose a variety of healthy proteins such as lean meat, chicken, seafood, legumes, nuts and seeds. Also limit red meat to one to 3 times per week.
• Eat oily fish such as salmon, sardines and mackerel at least twice a week.
• Incorporate healthy fat choices such as nuts, seeds, avocados, olives and oils for cooking.
• Use herbs and spices to flavour meals, instead of salt.

How to avoid saturated fats

To assist with lowering cholesterol levels, reducing foods high in saturated fats can help. Try to minimise intake of:

• fatty meats
• processed meats like salami and sausages
• snack foods like chips
• most takeaway foods, especially deep-fried foods
• cakes, biscuits and pastries.

Foods that may lower cholesterol levels

LDL cholesterol can be lowered by polyunsaturated oil (for example, sunflower or safflower oil).

Eating oats and legumes can lower LDL cholesterol by 5%.

Food components like saponins (found in chickpeas, alfalfa sprouts and other foods) and sulphur compounds (like allicin – found in garlic and onions) may also have a positive effect in lowering cholesterol levels.

Plant sterols can lower cholesterol levels

Plant sterols can lower cholesterol levels and are found naturally in plant foods including sunflower and canola seeds, vegetable oils and (in smaller amounts) in nuts, legumes, cereals, fruit and vegetables.

Some margarine, milks and cereals have concentrated plant sterols added to them. The recommended dose is 2 to 3 g per day. Consuming more than this amount does not lead to any harm, however, there are no additional benefits.

Lifestyle tips to cut cholesterol

Changing some of your lifestyle habits may also help to reduce your cholesterol and triglyceride levels. Suggestions include:

• Stop alcohol consumption or reduce your alcohol intake to no more than one or 2 drinks a day. Avoid binge drinking. This may help lower your triglyceride levels.
• Don’t smoke. Smoking increases the ability of LDL cholesterol to get into artery cells and cause damage.
• Exercise regularly (for example, at least 30 minutes of brisk walking daily). Exercise increases HDL levels while reducing LDL and triglyceride levels in the body.
• Reduce excess body fat. Being overweight may contribute to raised blood triglyceride and LDL levels.
• Manage your blood sugar levels within your target range if you have diabetes. High blood sugars are linked to an increased risk of atherosclerosis (‘hardening of the arteries’), heart attacks and strokes.

Medication may be needed for high cholesterol

For some people, diet and lifestyle changes are not enough to lower cholesterol. High blood cholesterol levels often have a genetic component. Some people inherit altered genes that cause high cholesterol and this cannot usually be changed sufficiently by lifestyle or diet.

If you are at risk of coronary heart disease and your LDL cholesterol level doesn’t drop after making dietary and lifestyle changes, your doctor may recommend medications to reduce your blood LDL levels.

Statins are the most common medication used to lower blood cholesterol.

Satins slow the amount of cholesterol made in your liver. The liver uses the cholesterol already in your blood instead. This lowers the level of LDL cholesterol in your blood.

If statins do not lower your cholesterol enough, you may need additional medicines.

Some people get muscle aches from statins. However, diet and exercise will still be important, even if you are taking medication. Your doctor may also refer you to a specialist who treats cardiovascular disease.

Where to get help

• Your doctor (GP)
• Dietitians Australia Tel. 1800 812 942
• Heart Foundation Tel. 13 11 12