Cholesterol is a type of fat (lipid) made by the body. It's essential for good health and is found in every cell in the body. However, having a high cholesterol level in the blood (hypercholesterolaemia) can increase the risk of heart disease and stroke.
About two in three adults have a cholesterol level that is higher than recommended. Having high cholesterol affects your heart and blood vessels and increases your risk of developing cardiovascular disease (CVD). High cholesterol causes fatty deposits (known as plaques) to build up inside your blood vessels.
In time, the blood vessels supplying your heart may become so narrow that they can't deliver enough oxygen to the heart muscle, particularly when you're exerting yourself. This can cause you to feel chest pain (angina). If a fatty plaque breaks off, it may cause a blood clot which can block blood flow to your heart (heart attack) or brain (stroke).This information was published by Bupa's health information team and is based on reputable sources of medical evidence. It has been peer reviewed by Bupa doctors. The content is intended for general information only and does not replace the need for personal advice from a qualified health professional.
Cholesterol is transported around your body attached to a protein in your blood. This combination of fat and protein is called a lipoprotein. There are different types of lipoprotein, depending on how much fat there is in relation to protein.
HDL (high-density lipoprotein)
A small amount of cholesterol is transported as HDL, which is mostly protein and not much fat. The role of HDL is to transport excess cholesterol from the tissues (including the walls of arteries) to the liver for disposal. As HDL helps prevent cholesterol building up in your blood vessels, you have a decreased risk of heart disease if you have high levels of this type. HDL is considered to be the "good" type of cholesterol. Women tend to have higher HDL levels than men. HDL can be increased by physical exercise.
LDL (low-density lipoprotein)
Most of your body's cholesterol (around 70 percent) is transported in this form. It consists mainly of fat, with not much protein. LDLs are chiefly involved in transporting cholesterol from the liver to the cells. High levels of LDL are associated with an increased risk of CVD as LDL causes cholesterol to be deposited in your blood vessels. LDL is considered to be the "bad" type of cholesterol.
VLDL (very low-density lipoprotein) and chylomicrons
These lipoproteins account for a small percentage of your body's cholesterol, but they are rich in triglycerides and transport them to the tissues.
Triglycerides are a different type of fat, mostly coming from fats in your food. Energy from food that is eaten and not used immediately is converted into triglycerides and transported to fat cells for storage. This provides you with an important source of stored energy.
Although most triglycerides are stored as fat, low levels are also found in your blood. A raised level of blood triglycerides together with high LDL can increase your risk of heart disease, particularly if you have diabetes.
Total cholesterol (TC)
Having a high TC level is a risk factor for future health problems. However, it's important to consider the relative amounts of HDL and LDL. This is often referred to as the TC:HDL ratio. You should aim for a high level of HDL and a low level of LDL (a low TC:HDL ratio).
A high cholesterol level may only be revealed if you develop symptoms of heart disease. Sometimes, yellow patches (known as xanthomas) may develop around your eyes or elsewhere on your skin - these are cholesterol deposits and indicate that you have high cholesterol levels in your blood.
There is an increased risk of heart disease, arterial disease and strokes. Your GP will discuss possible complications of high cholesterol with you.
There are several factors that may contribute to you having high blood cholesterol. These include:
- a diet high in saturated fat and cholesterol
- a lack of exercise - this can increase your LDL levels and decrease your HDL levels
- family history - you're more likely to have high cholesterol if you have a close male relative aged under 55 or a female relative aged under 65 affected by heart disease
- being overweight
- age and gender - your cholesterol levels generally rise with increasing age, and men are more likely to be affected than women
- drinking more than the recommended daily amount of alcohol
Rarely, high cholesterol can be caused by a condition which may run in your family - this is called 'familial hypercholesterolaemia'. About one in 500 people have this condition.
Other conditions such as poorly controlled diabetes, certain kidney and liver diseases, and an underactive thyroid may also cause high cholesterol. Some medicines such as beta-blockers, steroids or thiazides (a type of diuretic) may also affect blood lipid levels.
Measuring cholesterol involves a blood test. Usually you will be asked not to eat for 12 hours before the test so that your food is completely digested and doesn't affect the test. A blood sample may be taken either by a needle and a syringe, or by a finger prick. You can have this test done at your GP surgery, at hospital, or as part of a health assessment examination.
Home-testing kits for cholesterol are also available but may not be very accurate. Speak to your pharmacist about your result if you choose to use a kit.
The amount of cholesterol in your blood is measured in units called millimoles per litre of blood, usually shortened to 'mmol/litre', 'mmol/L' or 'mM'. Current UK guidelines state that it's desirable to have a total cholesterol level under 5mmol/L, and an LDL level under 3mmol/L. However, you should aim to have a total cholesterol level under 4mmol/L and an LDL level under 2mmol/L if you're at high risk of heart disease.
Who should have a cholesterol test?
You should have your cholesterol levels regularly checked by your GP if you have CVD (or are at high risk of CVD) or if you have a family history of high cholesterol.
There are two ways to help lower high cholesterol. The first is with lifestyle changes including changing your diet, managing your weight and increasing exercise. The second is to combine lifestyle changes with cholesterol-lowering medicines.
Healthy eating can reduce cholesterol. Your diet should be low in saturated fats in particular, and low in fat overall. Biscuits, cakes, pastries, red meat, hard cheese and butter all tend to be high in saturated fats, so cut down on these foods.
Some foods contain cholesterol. These foods include eggs, prawns and offal such as liver and kidneys. This type of cholesterol is known as dietary cholesterol and it has a much lower effect on blood cholesterol than saturated fat in your diet. You don't need to cut down on these foods unless your doctor has advised you to.
It's also important to eat plenty of fibre, especially soluble fibre, which is thought to lower cholesterol. Soluble fibre is found in fruits and vegetables, beans and oats. Aim to eat at least five portions of fruit and vegetables each day. Foods containing substances called plant sterols or stanols may help to lower cholesterol.
If you're overweight, an excess weight loss plan may help you to reduce your LDL levels and increase your HDL levels. Increasing your physical activity may enhance the cholesterol-lowering effects of diet.
As high cholesterol can increase your risk of heart disease, you should reduce any additional risk of developing heart disease, eg by stopping smoking.
Your GP may prescribe cholesterol-lowering medicines if you already have heart disease, or are at high risk of getting it because you have other risk factors. The aim of treatment is to reduce your total cholesterol levels by a quarter or to less than 4mmol/L.
The main group of medicines for lowering cholesterol are the statins. Available statins include atorvastatin (Lipitor), fluvastatin (Lescol), pravastatin (Lipostat), rosuvastatin (Crestor) and simvastatin (Zocor). They work by reducing the production of cholesterol in the liver. These medicines can have side-effects such as indigestion and muscle pains.
Other types of medicines to reduce cholesterol include fibrates, nicotinic acid and cholesterol-absorption inhibitors such as ezetimibe (Ezetrol), but these are generally less effective than statins or have more side-effects. Your GP can tell you more about these medicines and suggest the most suitable treatment for you.
1. How do the fats in my food affect my cholesterol levels?
Fat is a good source of energy but eating too much of the wrong types of fat increases your cholesterol levels and therefore your risk of heart disease.
Some fat is an essential part of a healthy diet but it's important that you don't eat too much of it and that you're careful about the type of fat that you eat.
The fat in your blood is turned into cholesterol by your liver. The cholesterol then enters your blood to be transported around your body. Not all cholesterol is bad for you; there is a harmful form and a protective form. The harmful form of cholesterol is known as LDL or low-density lipoprotein. The protective form of cholesterol is known as HDL or high-density lipoprotein.
You should reduce the amount and type of fat that you eat to help reduce your cholesterol level. There are different types of fat in food.
- Saturated fats - these increase cholesterol levels. Examples of foods high in saturated fat include cakes and biscuits, pastry, meat products and hard cheese.
- Trans fats - these have a similar effect on cholesterol levels as saturated fats. Foods containing hydrogenated vegetable oil, which must be listed in the ingredients list 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.
- Mono-unsaturated fats - these help lower harmful cholesterol levels. Examples of foods high in mono-unsaturated fats include olive oil and rapeseed oil.
- Polyunsaturated fats - these lower both harmful and protective cholesterol levels. Examples of foods high in polyunsaturated fats include sunflower oil and soya oil.
When you're shopping for food, compare the labels so you can pick those with less total fat or less saturated fat. Try and choose lower fat versions of dairy foods, such as semi-skimmed or skimmed milk, and reduced-fat yoghurt, whenever you can.
There is a particular type of polyunsaturated fat called omega-3 which can help to reduce your cholesterol levels. You can get omega-3 fats from:
- oily fish, such as kippers, mackerel, sardines and salmon
- certain oils, such as rapeseed, walnut and linseed oil
- fish-oil supplements
You should aim to eat at least one portion of oily fish per week, although you should limit this to a maximum of two portions per week if you're pregnant or breastfeeding.
If you're worried about high cholesterol, ask your GP for advice.
2. What is the "normal" level of cholesterol that I should have in my blood?
Cholesterol plays an important role in your body's cells. However, too much cholesterol in your blood can increase your risk of heart problems. If you're not receiving any medicines to reduce your cholesterol levels, you should aim for a total cholesterol level of 5mmol/L or less. If you're at risk of developing heart disease, then your GP may advise you to aim for a total cholesterol level under 4mmol/L.
Most cholesterol is made by your body and this fatty substance plays an essential role in how every cell in your body works. Cholesterol is transported around your body attached to a protein in your blood. This combination of fat and protein is called a lipoprotein and there are several types of lipoprotein, depending on how much protein there is in relation to fat.
Nearly three-quarters of your body's cholesterol is transported in your blood as low-density lipoproteins (or LDL). LDL is considered to be the "bad" type of cholesterol as it causes cholesterol to be deposited in your blood vessels. Smaller amounts of cholesterol are transported in high-density lipoproteins (or HDL) and very low-density lipoproteins (or VLDL). HDL is considered to be the "good" type of cholesterol as it helps prevent cholesterol building up in your blood vessels. VLDLs are rich in triglycerides, a different type of fat from cholesterol, which mostly come from fats in your food.
Generally, the levels of cholesterol in your blood are considered by your GP as part of your overall cardiovascular risk. The following fat levels are generally regarded as being desirable if you're not receiving any cholesterol-reducing medicines.
- Your total cholesterol should be 5mmol/L or less and your total cholesterol/HDL cholesterol ratio should be 4.5 or less.
- You should aim to have an LDL cholesterol level (while fasting) of 3mmol/L or less, while your HDL cholesterol level should ideally be 1.2mmol/L or higher.
- The level of triglycerides in your blood when fasting should ideally be 1.5mmol/L or less.
It's important to remember that there are different types of fat in food, each of which can affect your cholesterol levels.
- Saturated fats increase your cholesterol levels. Foods typically high in saturated fat include cakes and biscuits, pastry, meat products and hard cheese.
- Trans fats have a similar effect on cholesterol levels as saturated fats. Trans fats can be found in biscuits and cakes, fast food and some margarines, although they don't need to be shown on food labels.
- Mono-unsaturated and polyunsaturated fats can help to lower your cholesterol level. Olive oil and rapeseed oil are both high in mono-unsaturated fats. Sunflower oil and soya oil are both high in polyunsaturated fats.
You should aim to reduce your cholesterol level by reducing the overall amount and type of fat that you eat. When you're shopping for food, compare the labels so you can pick those with less total fat or less saturated fat. Try and choose lower-fat versions of dairy foods, such as semi-skimmed or skimmed milk and reduced-fat yoghurt, whenever you can.
If you want to cut down on fats in your diet, you can compare the labels of different food products and choose those with less total fat and less saturated fat. Foods high in fat typically have more than 20g fat per 100g, whereas low-fat foods have 3g of fat or less per 100g. For saturated fat, which increases cholesterol levels, a high level is more than 5g of saturates per 100g. Food low in saturated fats contain 1.5g saturates or less per 100g.
- British Heart Foundation
0300 330 3311
- Heart UK
0845 450 5988
- Food Standards Agency
- British Nutrition Foundation
020 7404 6504
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