High cholesterol

Published by Bupa's Health Information Team, December 2010.

This factsheet is for people who have high cholesterol, or who would like information about it.

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 level of certain types of cholesterol in the blood (hypercholesterolaemia) can increase the risk of heart disease and stroke.

What cholesterol is and what blood tests for high cholesterol show

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About high cholesterol

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 your 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).

Types of cholesterol

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 high-density lipoprotein (HDL), which is mostly protein and not much fat. HDL transports excess cholesterol from the tissues (including the walls of arteries) to your 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 often called ‘good’ cholesterol.

Women tend to have higher HDL levels than men. Physical activity can increase HDL.

LDL (low-density lipoprotein)
Most of your body's cholesterol (around 70 percent) is transported as low-density lipoprotein (LDL). It consists mainly of fat, with not much protein. LDL transports cholesterol from your liver to the cells. High levels of LDL increase your risk of CVD because LDL causes cholesterol to build up in your blood vessels. LDL is often called ‘bad’ cholesterol.

Triglycerides
Triglycerides are a different type of fat, mostly coming from fats in your food. Energy from your food that isn’t 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, smoke or have high blood pressure.

Total cholesterol (TC)
Having a high total cholesterol 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 total to HDL cholesterol ratio (TC:HDL). You should aim for a high level of HDL and a low level of LDL (a low total to HDL ratio).

Symptoms of high cholesterol

You may only find out that you have high cholesterol if you develop symptoms of heart disease. Sometimes, yellow patches (called xanthomas) may develop around your eyes or elsewhere on your skin – these are cholesterol deposits and may show that you have high cholesterol.

Complications of high cholesterol

High cholesterol increases the risk of heart disease, arterial disease and strokes. Your GP will discuss possible complications of high cholesterol with you.

Causes of high cholesterol

There are several factors that may contribute to you having high cholesterol. These include:

• a diet high in saturated fat
• a lack of exercise – exercise can increase your HDL levels
• obesity (BMI of 30 or more)
• age and gender – your cholesterol levels generally rise with increasing age, and men younger than 55 are more likely to be affected than women, but over 55, women are more likely to be affected
• drinking more than the recommended daily amount of alcohol
• smoking

High cholesterol can sometimes be caused by a condition that runs in your family called 'familial hypercholesterolaemia'. About one in 500 people have this condition. It’s not caused by an unhealthy lifestyle but is passed through the family through a faulty gene.

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.

Diagnosis of high cholesterol

Your cholesterol level is measured with 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. Your GP or nurse may take a blood sample using either a needle and syringe, or a finger prick. You can have your cholesterol tested 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'. There is no recommended level for total cholesterol or LDL cholesterol.

When looking at your cholesterol levels, your GP will consider how much HDL you have compared to LDL. This is called your total cholesterol to HDL cholesterol ratio. You can work this out by dividing your total cholesterol level by your HDL level. It’s healthiest to have high HDL, low LDL and low total cholesterol, with a total to HDL ratio of less than four.

Who should have a cholesterol test?

Your GP should check your cholesterol levels every year if you have CVD. If you’re at high risk of CVD or you have a family history of high cholesterol, your GP should check your cholesterol. He or she will talk to you about how often it should be checked.

Treatment 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.

Self-help

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 may need to cut down on these foods if your GP advises you to.

It's also important to eat plenty of fibre, especially soluble fibre, which helps to lower cholesterol. There is soluble fibre 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, losing your excess weight loss can reduce LDL levels and increase HDL levels. Increasing your physical activity may enhance the cholesterol-lowering effects of your 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.

Medicines

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 5mmol/L.

The main group of medicines for lowering cholesterol are the statins. Available statins include simvastatin, atorvastatin, fluvastatin, pravastatin, and rosuvastatin. 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. However if you have very high cholesterol, your GP may prescribe ezetimibe with statins. Your GP can tell you more about these medicines and suggest the most suitable treatment for you.

Prevention of high cholesterol

You may be able to prevent high cholesterol by keeping to a healthy weight and eating a diet that is low in saturated fat. Try to include at least two portions of fish, of which at least one should be an oily fish such as mackerel or salmon. There is no need to take omega-3 supplements or eat spreads, yoghurts or other foods containing plant stanols or sterols. You shouldn’t smoke or drink too much alcohol, and you should take regular exercise. However, if your family has a history of high cholesterol, it may be difficult to prevent yourself from having it too.

For answers to frequently asked questions on this topic, see FAQs.

For sources and links to further information, see Resources.