High cholesterol

Your health expert: Dr Lewis Caplin, Lead Physician, Bupa
Content editor review by Rachael Mayfield-Blake, November 2023
Next review due November 2026

Cholesterol is a type of fat that’s made by your body and is found in some foods. You have cholesterol in every cell of your body – it’s vital for good health. But although your body needs cholesterol to work properly, too much of some types of cholesterol can harm your health.

About high cholesterol

Cholesterol has an important role in the way your body works. Your body needs cholesterol to:

• make hormones and vitamin D
• make bile acids, which help your gut to digest the food you eat
• construct the outer layer (membrane) of your body’s cells

But if you have a high level of certain types of cholesterol, you increase your risk of cardiovascular disease – for example, heart disease and stroke. This is because one type of cholesterol can cause fatty deposits (known as plaques) to build up inside your arteries. Over time, these can make your arteries narrower and narrower, which restricts the flow of blood to organs such as your heart. This can affect other parts of your body too, including your arms and legs (peripheral arterial disease).

There’s plenty you can do to manage cholesterol and keep it at healthy levels

Types of cholesterol

A protein in your blood carries cholesterol around your body. This combination of fat and protein is called a lipoprotein. There are different types of lipoprotein, and they may be harmful or beneficial to your health. This is why you may have heard about ‘good’ cholesterol and ‘bad’ cholesterol.

Good cholesterol

High-density lipoprotein (HDL) helps to get rid of excess cholesterol by carrying it from your tissues to your liver. Your liver then breaks down the cholesterol so your body can get rid of it. Your liver uses it to make bile that helps with digestion, and some of this is removed from your body as a waste product in your poo.

Having modest amounts of HDL cholesterol in your blood is a good thing – it helps to prevent heart disease, so HDL is often called ‘good’ cholesterol.

Bad cholesterol

Non-high-density lipoproteins or non-HDL, including low-density lipoprotein (LDL) carries cholesterol from your liver to the cells around your body where it’s needed. But if the level of non-HDL in your blood is too high, it can cause fatty deposits to build up in your blood vessels (atherosclerosis). This can increase your risk of heart disease and stroke, so LDL is often called ‘bad’ cholesterol.

LDL is the main ‘bad’ cholesterol, but there are some other types which can also be harmful. That’s why all non-HDL cholesterol is known as the ‘bad’ cholesterol. Non-HDL cholesterol is ‘all the cholesterol in your blood which isn’t good cholesterol’.

Causes of high cholesterol

High cholesterol is can be caused by a number of things, which all act to increase your cholesterol level. As well as your family history, high cholesterol causes may include:

• a diet that’s high in saturated fat or trans fats
• not doing much exercise
• being overweight or obese
• drinking too much alcohol
• smoking

Sometimes, high cholesterol is caused by a condition that runs in your family called familial hypercholesterolaemia. This means you may have a very high cholesterol level, even if you have a healthy lifestyle.

Other health conditions may be linked to high cholesterol. These include:

• poorly controlled diabetes
• high blood pressure
• certain kidney and liver diseases
• an underactive thyroid (hypothyroidism)
• menopause

Some medicines can raise your cholesterol. These include:

• oral contraceptives or menopause medicines
• steroids
• beta blockers

Symptoms of high cholesterol

High cholesterol doesn’t cause any symptoms by itself. But if you have high cholesterol, it can lead to serious problems that affect your heart and circulation – for example, heart attack and stroke. You may start to develop symptoms of heart disease – for example, angina (chest pain that comes on with exertion and is relieved by rest). Or you may have pain in your calves on exercise which goes away when you rest.

Contact your GP if you have symptoms you’re concerned about. If you have chest pain, contact your GP as soon as possible.

Diagnosis of high cholesterol

Measuring cholesterol

Your GP can measure your cholesterol levels with a blood test. The test measures the different types of cholesterol and the total amount of cholesterol in your blood. It may also measure another type of fat called triglycerides. A high level of triglycerides is also a risk factor for heart disease and stroke.

Your GP surgery will tell you how to prepare for the test. They may ask you not to eat anything for about 10 to 12 hours before you have the blood test but this is not always the case. Always follow any instructions your doctor or GP surgery gives you.

It’s important for everyone to aim for healthy blood cholesterol levels. This means:

• low total cholesterol
• low level of non-HDL cholesterol
• a moderately high level of HDL cholesterol

Here’s a general guide to cholesterol levels in healthy adults:

• total cholesterol (TC): 5mmol/L or below
• non-HDL (all ‘bad’) cholesterol: 4mmol/L or below
• LDL (main ‘bad’) cholesterol: 3mmol/L or below
• HDL (‘good’) cholesterol: 1mmol/L or above for men, 1.2 mmol/L for women
• cholesterol ratio TC/HDL: 6mmol/L or below
• triglycerides: 2.3mmol/L or below

These figures only give a general idea of normal cholesterol levels. It’s important to discuss with your doctor or nurse what your test results mean for you individually. They’ll take into account other factors, such as your age, sex, body mass index (BMI), blood pressure, family history, and if you smoke. They’ll also consider other health conditions you may have or medicines that you take.

Cholesterol levels in your blood can vary from day to day. So, your doctor may want to repeat the test before they recommend any treatment.

Who should have a cholesterol test?

When you reach 40, your GP may offer you a cholesterol test. This will be part of a health check that you have every five years to work out your risk of developing heart disease and stroke.

Your GP may also offer you a cholesterol test if you:

• have a high blood pressure
• have diabetes
• are overweight or obese
• have a family history of high cholesterol (known as familial hypercholesterolaemia)
• have heart disease
• smoke
• are unable to get or maintain an erection (erectile dysfunction)
• have kidney disease

Treatment of high cholesterol

The main group of medicines for high cholesterol are called statins. Your GP may recommend you take a statin if you have made changes to your lifestyle but they haven’t reduced your cholesterol level enough. You should still stick to these lifestyle changes while you take statins. Or your GP may recommend statins from the start if you have a risk of problems like heart disease.

It’s your choice whether or not you take statins. To help you to make a decision, your doctor will discuss their risks and benefits with you before you start any treatment.

Your GP will usually ask to check your cholesterol level again around three months after you’ve started this high cholesterol treatment, to see how well it’s working. If you don’t get on with your treatment or it’s not working well, your GP may suggest changing the dose or trying a different statin. They may recommend alternative medicines or seek specialist advice if you find you can’t tolerate statins even after trying three different kinds. Most people don’t have any side-effects from statins and can take them without any problems.

You shouldn’t take statins if you’re pregnant. And if you plan to get pregnant, stop taking statins three months before you start trying.

Prevention of high cholesterol

High cholesterol is often preventable if you make changes to your lifestyle and diet. See our self-help section for information on how to make these healthy changes. You can also find some tips on maintaining healthy cholesterol levels.