Cholesterol is found in every cell of the body and has important natural functions. It is manufactured by the body but can also be taken in from food. It is waxy and fat-like in appearance.
Cholesterol is oil-based and so does not mix with the blood, which is water-based. It is therefore carried around the body in the blood by lipoproteins.
The parcels of cholesterol are carried by two types of lipoprotein:
Cholesterol has four main functions, without which we could not live. It:
High levels of LDL lead to a build-up of cholesterol in the arteries, whereas HDL carries cholesterol to the liver for removal from the body. A build-up of cholesterol forms part of the process that narrows arteries, called atherosclerosis, in which plaques form and cause restriction of blood flow.
Two types of cause lead to high cholesterol levels – modifiable and non-modifiable risk factors. The major two risk factors are highly modifiable – something can be done to change them:
Limiting intake of fat in the diet helps manage cholesterol levels, limiting foods, in particular, that contain:
Being overweight or obese can lead to higher blood LDL levels so exercise can help manage this risk factor.
The primary causes of high cholesterol are genetic – very high LDL levels are found in the inherited condition familial hypercholesterolemia.
Abnormal cholesterol levels may also be secondary to the following:
Fast facts on cholesterol
Here are some key facts about cholesterol. Find more detail and supporting information in the article.
Having high cholesterol levels, while a risk factor for other conditions, does not itself present any signs or symptoms. Unless routinely screened through regular blood testing, high cholesterol levels will go unnoticed and could present a silent threat of heart attack or stroke.
High cholesterol can only be diagnosed by blood testing. Doctors’ guidelines state that everyone over the age of 20 years should have their cholesterol levels checked once every five years.
The cholesterol test is done after a period of fasting – no food, drink or pills for 9 to 12 hours – to enable an accurate reading of LDL cholesterol from the blood test. The screening also gives information about total cholesterol, HDL cholesterol and triglyceride levels.
The guidelines set cholesterol levels that help determine the individual heart risk, as follows:
Guidance is also set out for the other measures in the lipid profile:
Four changes to lifestyle are recommended for all people with high cholesterol levels – including those receiving drug treatment – in order to reduce the risk of coronary heart disease and heart attack:
Cholesterol levels play a major part in an individual’s risk of having a heart attack within the next ten years. The National Heart, Lung and Blood Institute provide an online calculator of cardiovascular risk. Using research evidence, it weighs the risk dictated by these factors:
Monitoring the ten-year risk according to data from the Framingham Heart Study, which continues today, helps in the management of lifestyle and other measures to reduce cholesterol levels, and so cut the chances of cardiovascular disease leading to heart attack or stroke.