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What is cholesterol?

Cholesterol is a soft, fatty substance in the blood which plays an important role in cell membranes, to manufacture many hormones and bile for digestion. Most of the cholesterol in the body is manufactured in the liver and then transported by the blood to the rest of the body. Some foods we eat from animal sources contain cholesterol, and this is referred to as dietary cholesterol.

Why are high cholesterol levels dangerous?

Everyone has cholesterol in their blood but too much cholesterol increases the risk of having a heart attack or a stroke. High blood cholesterol levels can slowly cause build-up of cholesterol and other waste products in the inner walls of arteries.

If left unchecked, it can eventually form plaques; thick hard deposits that can narrow arteries and make them less flexible. This process is called atherosclerosis. If a clot forms and blocks a narrowed artery that feeds the heart or brain, it can result in a heart attack or stroke. High cholesterol is one of the most important risk factors for cardiovascular disease.

‘Good’ and ‘bad’ cholesterol

Cholesterol that is transported from the liver to the rest of the body is carried in transporters called low density lipoproteins, commonly known as LDL. A different transporter, called high density lipoprotein or HDL, collects cholesterol from the rest of the body and the blood vessels, and returns it to the liver.

Because high levels of LDL cholesterol are associated with heart disease, it is often called ‘bad cholesterol’. HDL ‘cleans’ the blood vessels of cholesterol and is therefore commonly referred to as ‘good’ cholesterol.

Blood cholesterol tests often also include a triglyceride test. This is a measure of the amount of fat that is being transported in the blood, which could be from fatty food that was recently eaten, or from fat production in the liver. High fasting levels of triglycerides in the blood increases the risk of heart diseases and strokes.

How can cholesterol levels be lowered?

Depending on the individual’s risk profile, a doctor may recommend medication or first making lifestyle changes. Whether someone is started on medication or not, diet, physical activity and lifestyle changes are critical.

Changes to the eating habits and other lifestyle factors can help to improve abnormal cholesterol levels. Read more about how this can improve the different types of blood cholesterol levels below.

For more advice, contact The Heart and Stroke Foundation South Africa on 021 422 1586 or email

Content was last reviewed in November 2017. Dietary advice for the management of cholesterol is based on the 2016 European Society of Cardiology and European Atherosclerosis Society Guidelines for the Management of Dyslipidaemias.