Cholesterol is needed for the body to function normally. It's mainly made by the liver, but can also be found in some foods. High cholesterol itself doesn't usually cause any symptoms, but it increases your risk of serious health conditions.
Cholesterol is carried in your blood by proteins. When the two join, they're called lipoproteins.
The two main types of lipoprotein are:
- high-density lipoprotein (HDL) – HDL is known as ’good cholesterol’, and higher levels are better
- low-density lipoprotein (LDL) – can build up in the artery walls, leading to disease of the arteries; for this reason, LDL is known as ’bad cholesterol’
The amount of cholesterol in the blood – both HDL and LDL – can be measured with a blood test.
Evidence indicates that high cholesterol can increase the risk of:
- narrowing of the arteries (atherosclerosis)
- heart attack
- transient ischaemic attack (TIA) – often known as a ’mini stroke’
- peripheral arterial disease (PAD)
This is because cholesterol can build up in the artery wall. This restricts the blood flow to your heart, brain and the rest of your body. It also increases the risk of a blood clot developing somewhere in your body.
Your risk of developing coronary heart disease also rises as your blood's cholesterol level increases. This can cause pain in your chest or arm during stress or physical activity (angina).
Causes of high cholesterol
Many factors can increase your chances of having heart problems or a stroke if you have high cholesterol.
- an unhealthy diet – in particular, eating high levels of saturated fat
- having diabetes or high blood pressure (hypertension)
- having a family history of stroke or heart disease
There's also an inherited condition which can cause high cholesterol even in someone who has a healthy lifestyle and does not have other risk factors.
Getting tested for cholesterol levels
Your GP may recommend that you have your blood cholesterol levels tested if you:
- have been diagnosed with coronary heart disease, stroke or mini stroke (TIA), or peripheral arterial disease (PAD)
- have a family history of early cardiovascular disease
- have a close family member who has a cholesterol-related condition
- are overweight
- have high blood pressure, diabetes, or a health condition that can increase cholesterol levels
You should probably be asked not to eat for 10-12 hours before the cholesterol test, usually including when you're asleep at night. This ensures all food is completely digested and won't affect the outcome of the test.
After your cholesterol test, your GP or nurse will explain your results and calculate whether you have a high, moderate or low risk of developing heart disease, stroke or other circulation problems (cardiovascular disease) within the next 10 years.
However, this risk isn't just based on your cholesterol reading. It also takes into account:
- your BMI (body mass index) – which measures your weight compared to your height
- treatable risk factors – such as high blood pressure (hypertension), diabetes and other medical conditions
- your age, sex, family history and ethnicity
As a general guide, total cholesterol levels should be:
- 5mmol/L or less for healthy adults
- 4mmol/L or less for those at high risk
Based on your results, your GP or nurse will recommend steps you can take to reduce your risk of developing cardiovascular disease (see below). Cholesterol-lowering medication, such as statins, may also be recommended.
Things to help lower cholesterol level
The first step in reducing your cholesterol is to maintain a healthy, balanced diet. It's important to keep your diet low in fatty food.
You can swap food containing saturated fat for fruit, vegetables and wholegrain cereals.
If these measures don't reduce your cholesterol and you continue to have a high risk of developing heart disease, your GP may prescribe a cholesterol-lowering medication
Your GP will discuss treatment options with you.