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.
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.
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.
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.
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.
Most people with high cholesterol feel perfectly healthy, there are usually no warning signs, which is why high cholesterol is often called a “silent killer”. The only way to find out is to have a blood test. For an accurate result, fast from food and liquids for at least 8 hours before the test. If a total cholesterol level is high, it is important to know what type of cholesterol is high.
What should my cholesterol reading be?
For most healthy people normal cholesterol levels are:
People who are at a higher than normal risk for cardiovascular events may have stricter individual targets as advised by their doctor or specialist. This includes people who have:
How often should cholesterol be tested?
All adults should have a fasting lipogram at least once in young adulthood (from age of 20). If cholesterol levels are normal, the test should be repeated again in a few years. People with diabetes, kidney disease or who are overweight should have their cholesterol levels monitored frequently by their doctor.
If ‘bad’ cholesterol levels are high or someone is at a high risk of heart disease, cholesterol levels should be checked every six months. Children don’t need to have their levels tested unless they have a family history.
There are various physical and lifestyle factors that can increase the likelihood of developing high blood cholesterol. Being aware of risk factors will help to identify the changes necessary to lower risk. Some of these risk factors include:
The most common medication to treat high cholesterol levels is a group of medications called statins. These medications reduce the amount of cholesterol produced in the liver, effectively reducing total and LDL cholesterol levels. Other medications include fibrates, ezetimibe, and several others. A doctor will decide whether someone should start cholesterol medication, and which type and dosage they need. As with most medications, a small percentage of people may experience side effects. If side effects occur, medication should not be stopped, but rather alternatives should be discussed with a doctor.
Cholesterol medication should be taken regularly to work, and may need to be taken indefinitely. Importantly, starting cholesterol medical should be done together with lifestyle changes, not instead of them!