Cholesterol is carried around your body by a protein in your blood. 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 ‘bad’ cholesterol and ‘good’ cholesterol. We describe the two main types of lipoprotein below.
High-density lipoprotein (HDL)
High-density lipoprotein (HDL) helps to get rid of excess cholesterol from your blood vessels. It does this by carrying cholesterol from your tissues (including the walls of arteries) to your liver. Your liver then breaks down the cholesterol so your body can get rid of it. As HDL helps prevent cholesterol building up in your blood vessels, it helps to reduce your risk of heart disease and stroke. This is why HDL is often referred to as ‘good’ cholesterol.
Low-density lipoprotein (LDL)
Low-density lipoprotein (LDL) carries cholesterol from your liver to the cells around your body where it’s needed. But if the level of LDL in your blood is too high, it can form fatty deposits in your arteries. This increases your risk of heart disease and stroke. For this reason, LDL is often called ‘bad’ cholesterol.
High cholesterol doesn’t cause any symptoms by itself. But if you have it, it can lead to serious problems affecting your heart and circulation, such as heart attack and stroke. You may start to develop symptoms of heart disease such as angina (chest pain that comes on with exertion and is relieved by rest). Contact your GP as soon as possible if you have this type of chest pain.
Your cholesterol level can be measured with a simple blood test. Your doctor or nurse may take a blood sample using either a needle and syringe, or a finger prick.
There are different types of cholesterol in your blood, and your blood test will show how much of each type you have. ‘Good’ cholesterol (high-density lipoprotein, HDL) helps to protect your body from heart disease and stroke, while ‘bad’ cholesterol (low-density lipoprotein, LDL) increases your risk. See our section on types of cholesterol above for more information.
Your doctor will look at how much HDL you have compared to your total cholesterol. The higher the ratio of total cholesterol to HDL, the higher your risk of getting heart disease and stroke. The blood test will also measure the levels of another type of fat in your blood, called triglycerides. A high level of triglycerides is also a risk factor for heart disease and stroke. You may be asked not to eat or drink anything except water for eight hours before your blood test. It’s important to follow any instructions you are given.
The levels of cholesterol in your blood can vary from day to day. For this reason, your doctor may want to repeat the test before recommending 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 to work out your risk of developing heart disease and stroke. The health check might also include measuring other factors, such as your weight and your blood pressure. Your GP will use the results from all these tests to calculate your risk of having a heart attack or stroke.
You’re said to be at higher risk if your risk of heart disease or stroke is 10 per cent or more over the next 10 years. This means, of 100 people with a similar risk factor, 10 or more would have a heart attack or stroke in the next 10 years.
Your GP may offer you a cholesterol test at other times if you have other reasons for an increased risk of heart disease and stroke. These include:
To begin with, your GP will recommend some lifestyle changes you can make in order to reduce your risk of heart attack and stroke. These may include:
- reducing the fat in your diet, particularly saturated fats. See our FAQ on fats in your food below for more information
- making other healthy changes to your diet – such as eating more fruit and vegetables, having less salt, and having some oily fish
- doing more physical activity
- losing any excess weight
- making sure you don’t drink more than the recommended alcohol limits
- stopping smoking if you smoke
Some foods have quite a lot of cholesterol in them. These include eggs, shellfish and offal. You might think you always need to avoid these if you have high cholesterol. However, experts think that it’s much more important to reduce the amount of saturated fats you eat. You should cut down on the high cholesterol foods if your doctor or dietitian advises you to.
The main group of medicines for lowering cholesterol are called statins. Your GP may recommend you take a statin if changes to your lifestyle haven’t reduced your cholesterol level enough. There are some other instances when you may be offered statins. These include if you have type I diabetes or kidney disease, or if you’ve already had a heart attack or stroke. Your GP may also offer you statins if you are 85 or over, taking into account whether the treatment is right for you personally.
Your GP will usually ask to check your cholesterol level again around three months after you’ve started treatment, to see how well it’s working. If you don’t get on with your treatment, or it’s not working very well, your doctor may suggest changing the dose or trying another statin.
It’s your choice whether or not you take statins. Your doctor will discuss the risks and benefits of taking statins with you before you start any treatment, to help you to make a decision. If you decide to take statins, there’s a chance you may get some side-effects (the unwanted effects of taking a medicine). Some common side-effects of statins include:
- muscle pain
- stomach and gut problems, such as indigestion, feeling sick, having constipation or diarrhoea
Statins can also cause inflammation of your liver. Your doctor will monitor possible side-effects by doing a liver function blood test before you start taking the statin and again a few months later. If your liver function is greatly affected, you may need a lower dose, or to take a different statin. However, if you only have mild changes then routine monitoring may be all that’s needed.
If you’d like more information about these and other side effects, read the patient information leaflet that comes with your medicine or ask your pharmacist. If the statins don’t help to lower your cholesterol, your GP may offer you a different type of medicine. You may be referred to a specialist for further treatment. Your GP may also seek specialist advice if you find you can’t tolerate statins even after trying three different kinds.
See our FAQ on statins below for more information about these medicines.
High cholesterol is often caused by a number of factors, which all act to increase your cholesterol level. These may include:
- having a diet high in saturated fat. See our FAQ on fats below for more information.
- not doing much exercise
- being overweight or obese
- drinking too much alcohol
Sometimes, high cholesterol can be 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. In the UK, about one in 500 people have this condition.
Other conditions, such as poorly controlled diabetes, certain kidney and liver diseases and underactive thyroid (hypothyroidism) may also cause high cholesterol. Some medicines can also raise your cholesterol, such as oral contraceptives, steroids and thiazide diuretics (a type of medicine to reduce your water level).
In most cases, high cholesterol is preventable through changes to your lifestyle and diet.
You can help to keep your cholesterol level low by staying at a healthy weight and eating a healthy diet. Your diet should be low in saturated fat and trans fats. Foods high in saturated fats include fatty meat (particularly red meat), biscuits, cakes and pastries. Trans fats are found in processed foods, such as cakes and biscuits. Try to replace these in your diet with foods that contain unsaturated fats – such as nuts and olive oil. See our FAQ on fats in your diet below for more information.
It also helps to take regular exercise, stop smoking if you smoke, and stick to recommended limits of alcohol.
Some fat is an essential part of a healthy diet. But it’s important that you’re careful about the type of fat that you eat and that you don’t eat too much of it. Eating certain types of fat can increase the amount of cholesterol your liver produces.
These are the different types of fat in the food we eat.
- Saturated fats – these increase your cholesterol levels. Examples of foods high in saturated fats include cakes and biscuits, pastry, meat products and hard cheese.
- Trans fats – these are similar to saturated fats in their effect on your cholesterol levels. Foods containing hydrogenated vegetable oil (which must be listed in the ingredients on the label) might contain trans fats. Trans fats currently don’t need to be labelled separately on food labels. They can be found in biscuits and cakes, fast food and some margarines.
- Monounsaturated fats – these help lower harmful cholesterol levels and increase protective cholesterol. Examples of foods high in monounsaturated fats include olive oil, avocados and nuts (eg, almonds, cashews, peanuts and pistachios).
- Polyunsaturated fats – these lower harmful cholesterol levels. Examples of foods high in polyunsaturated fats include sunflower oil, oily fish, and nuts and seeds (eg, walnuts, pine nuts, sesame and sunflower seeds).
When you’re shopping for food, compare the labels and pick those with less total fat or less saturated fat. Aim to replace saturated and trans fats in your diet with monounsaturated or polyunsaturated fats whenever you can. This may mean using olive or rapeseed oil to cook with rather than lard or butter, and using spreads based on these oils. Try to go for lower fat versions of dairy foods, such as semi-skimmed or skimmed milk, and reduced-fat yoghurt.
There’s a particular type of polyunsaturated fat called omega-3 which can help to reduce your cholesterol levels and keep your heart healthy. The best source of omega-3 fats is oily fish, such as mackerel, sardines and salmon. Try to eat two portions of fish per week, including a portion of oily fish. But don’t have more than two portions per week if you’re pregnant.
There’s no set recommended target for your cholesterol level. Generally, the lower your cholesterol, the better. Blood cholesterol is measure in units called milllimoles per litre (mmol/L). Most doctors agree that a total cholesterol level below 5 mmol/L and an LDL (‘bad’) cholesterol below 3 mmol/L is healthy. The figures to aim for may be lower if you have a high risk of heart disease and stroke. Your doctor or nurse will discuss this with you. See our section on types of cholesterol above for more information about ‘good’ and ‘bad’ cholesterol.
Whether or not you need treatment to lower your cholesterol level depends on your overall risk of having a heart attack or stroke. Your doctor will look at several factors to calculate this risk, not just your cholesterol level. These include your age, sex, body mass index (BMI), blood pressure, family history and whether you smoke. If you have any other illnesses such as diabetes, this will also be taken into account. This means you may be offered treatment to reduce your cholesterol, even if your cholesterol level is lower than someone who doesn’t need treatment.
If your doctor recommends you take a statin, they will be aiming to lower your cholesterol level by at least 40 per cent, no matter what your cholesterol level.
There are several different types of statin available in the UK. They vary in how well they work at reducing cholesterol. Your doctor will offer you a statin at a dose that is suitable for reducing your cholesterol levels, with as few side-effects as possible.
Examples of statins used in the UK include atorvastatin, simvastatin, and fluvastatin. All statins work in the same way. Statins lower the level of cholesterol in your blood, especially low-density lipoprotein (LDL) or ‘bad’ cholesterol.
If you need to take a statin, your doctor will usually offer you atorvastatin to try first. They’ll check your cholesterol levels regularly and if necessary, adjust the dose of your statin.
As with any medicine, you may have some side-effects when taking statins, but these are similar for all types of statin. See our section on treatment of high cholesterol above for more information.
Plant sterols and stanols are often added to certain food products, including certain spreads, yoghurts and mini-drinks. There’s some evidence that regularly consuming these products can help to reduce your level of LDL cholesterol. This is the ‘bad’ cholesterol in your blood that can cause the build up of fatty plaques in your arteries. However, there’s no evidence yet to prove that taking them also reduces your risk of heart attack and stroke.
It’s your choice whether or not to try sterols and stanols. Medical guidelines currently do not recommend them for people who have been advised to reduce their risk of heart disease and stroke. If you do decide to try taking them, you should still aim to make any lifestyle changes or take any medicines that your doctor advises. See our section on treatment of high cholesterol above for more information.
You shouldn’t take products containing sterols and stanols if you’re pregnant or breastfeeding, and they’re not suitable for children under the age of 5.
You can find more information about sterols and stanols from the websites shown in our resources section below.
- Hypercholesterolaemia. BMJ Best Practice. bestpractice.bmj.com, last updated January 2016
- Hyperlipidaemia. PatientPlus. patient.info/patientplus, last checked 31 July 2014
- Cholesterol-lowering sterols and stanols. PatientPlus. patient.info/patientplus, last checked 29 August 2014
- Overview of lipid metabolism. The MSD Manuals. www.msdmanuals.com, last full review/revision August 2015
- Atherosclerosis. The MSD Manuals. www.msdmanuals.com, last full review/revision September 2012
- Dyslipidaemia. The MSD Manuals. www.msdmanuals.com, last full review/revision August 2015
- Lipid modification – CVD prevention. NICE Clinical Knowledge Summaries. cks.nice.org.uk, last revised October 2015
- CVD risk assessment and management. NICE Clinical Knowledge Summaries. cks.nice.org.uk, last revised September 2014
- Cardiovascular disease: risk assessment and reduction, including lipid modification. National Institute for Health and Care Excellence (NICE), July 2014. www.nice.org.uk
- Atorvastatin. Joint Formulary Committee. British National Formulary (online) London: BMJ Group and Pharmaceutical Press. www.medicinescomplete.com, accessed 25 August 2016
- Cardiology and vascular disease. Oxford handbook of general practice (online). Oxford Medicines Online. www.oxfordmedicine.com, published April 2014
- Cholesterol. Food fact sheet. BDA: The Association of UK Dietitians, 2014. www.bda.uk.com
- Trans fats. Food fact sheet. BDA: The Association of UK Dietitians, 2014. www.bda.uk.com
- Fats. Food fact sheet. BDA: The Association of UK Dietitians, 2015. www.bda.uk.com
- Stanols and sterols. Food fact sheet. BDA: The Association of UK Dietitians, 2015. www.bda.uk.com
- High cholesterol. British Heart Foundation. www.bhf.org.uk, accessed 24 August 2016
- Cholesterol test. Lab tests online. The Association for Clinical Biochemistry & Laboratory Medicine. Labtestsonline.org.uk, last reviewed 29 May 2015
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Reviewed by Dr Kristina Routh, Freelance Health Editor, Bupa Health Content Team, August 2016.
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