High cholesterol: get the lowdown

Cholesterol is a type of fat used by our body for important everyday functions such as making hormones, and building and repairing cells. Cholesterol is made by your liver and is also found in some foods.

To reach cells throughout the body, cholesterol attaches to a carrier substance called lipoprotein that can travel in the bloodstream. The two most common types of lipoprotein are HDL (high density lipoprotein) and LDL (low density lipoprotein). They are often known as 'good' and 'bad' cholesterol, respectively.

HDL is good for your heart and blood vessel health because this lipoprotein helps to prevent blockages by moving cholesterol from cells through the blood and into the liver to be processed or excreted from the body.^1,3

LDL on the other hand carries cholesterol from the blood into cells of the body. This type of lipoprotein can deposit cholesterol in your artery walls, causing a build up of cholesterol (called plaques), which may ultimately cause the arteries to narrow.^1,3 This is known as atherosclerosis and depending on the arteries affected may result in chest pain (angina), a heart attack or a stroke.^1,3 Having high levels of LDL cholesterol can increase your risk of developing cardiovascular disease.1 This is especially important if you also have other risk factors, and is why lowering LDL cholesterol levels (and ideally raising HDL cholesterol levels) can have cardiovascular benefits – whether you already have, or are at risk of developing, cardiovascular disease, or just want to reduce your chances of ever having one of these conditions.

You are at higher risk of heart disease and stroke if you have high cholesterol and you:

• smoke
  
• aren't physically active
  
• have high blood pressure
  
• have diabetes
  
• are overweight or obese.
  

What causes high cholesterol levels?

Having high total cholesterol in your blood stream does not happen as the result of eating one high-fat meal. However, if you regularly eat foods that are high in saturated and trans fats (eg,. fatty and processed meats, take-away foods and store-bought baked goods) then you are more likely to have elevated levels of total and LDL cholesterol.³

Certain medical conditions (eg, diabetes, underactive thyroid) can also contribute to abnormal cholesterol levels.⁴

High cholesterol can also be inherited, which is the case in familial hypercholesterolaemia – where the body doesn't remove enough cholesterol from the blood. This condition affects 1 in every 500 Australians, although many do not know they have it.⁵

Most people won't experience any symptoms of high cholesterol until blood flow to parts of the body, especially heart or brain, is affected. When blood flow to the heart is reduced a person may experience chest pain (angina), and reduced or interrupted blood flow to the brain may result in stroke. Restrictions to blood flow can also increase the chance of blood clots forming, and the risk of complete arterial blockage, which can lead to a heart attack or stroke.

Eating a healthy diet and exercising regularly can help to lower your cholesterol. Prescription medicines that lower cholesterol are also available if diet and physical activity on their own are unable to reduce your cholesterol sufficiently.

Healthy lifestyle

Small changes can make a big difference to your health. Aim to:

• quit smoking
  
• be physically active for 30 minutes every day
  
• cut down on salt intake
  
• eat foods containing poly- and mono-unsaturated fats (eg, lean meats, oily fish, nuts, seeds, legumes)
  
• remove trans fats from your diet (often found in store-bought baked goods and snack foods).
  

Medicines

Statins are medicines that can be prescribed for people with high cholesterol who are at high risk of heart disease or stroke.

Statins are also commonly prescribed for people with various forms of cardiovascular disease – including those who have had a heart attack in the past – regardless of their cholesterol level.

Muscle pain is a commonly reported side effect of statin medicines; however, serious muscle problems are rare.⁶ If you are taking a statin and experience any muscle pain or weakness, report it to your doctor.

Other medicines that can help to lower cholesterol are available for people who can't take statins.

Fish oil supplements have been shown to lower blood trigycerides (a type of fat), but do not change LDL levels when given in standard doses.³ A recent review looking at the effect of omega 3 fatty acids (the active ingredient in fish oils) on heart disease has reported that these supplements do not reduce the risk of heart attacks, although eating fish does appear to be beneficial.⁷ Fish oil supplements should not be taken as a substitute for cholesterol-lowering medicines.

If you are 45 years or older (35 years or older for Aboriginal and Torres Strait Islander people), it is recommended that you have your cholesterol levels checked as part of a regular, more comprehensive, cardiovascular disease risk assessment – conducted at intervals as advised by your doctor.⁸ Talk to your doctor about your risk of heart disease and stroke especially if you have:

• had a heart attack or stroke
  
• high blood pressure
  
• diabetes
  
• a family history of high cholesterol or heart disease
  
• chronic kidney disease.
  

Visit the Heart Foundation website for more information.