Cholesterol (Lipids)

Cholesterol is a waxy substance made in liver, from the saturated fats in food. Cholesterol plays a vital role in how every cell works, however too much cholesterol can increase your risk of getting heart and circulatory disease. (Heart and circulatory disease includes coronary heart disease, stroke, and diseases that affect the circulation such as peripheral arterial disease.) There are two main types of cholesterol- called LDL cholesterol (bad cholesterol) and HDL cholesterol (good cholesterol). HDL cholesterol is a ‘good’ type of cholesterol because it removes the bad cholesterol from the bloodstream rather than depositing it in the arteries.

Triglycerides are another type of fatty substance in the blood. They are found in foods such as dairy products, meat and cooking oils. People with a high triglyceride level have a greater risk of coronary heart disease and stroke than people with lower levels.

The best way to control your cholesterol and triglyceride level is to do regular physical exercise (activities) and eating low fatty food.

cholesterol

Blood lipids is the name for all the fatty substances in the blood, including cholesterol and triglycerides.

Cholesterol

Cholesterol is a waxy substance, which is mainly made in the body. The liver makes it mostly from the saturated fats in food. (Very little cholesterol is found in foods, except for eggs, liver and kidneys, and seafood such as prawns, all of which do contain some cholesterol.)

Cholesterol plays a vital role in how every cell works, throughout the body. It is also the material, which the body uses to make other vital chemicals. However, too much cholesterol in the blood can increase your risk of getting heart and circulatory disease. (Heart and circulatory disease includes coronary heart disease, stroke, and diseases that affect the circulation such as peripheral arterial disease.)

LDL cholesterol and HDL cholesterol

Cholesterol has a special ‘transport system’ for reaching all the cells, which need it. It uses the blood circulation as its ‘road system’ and is carried on ‘vehicles’ made up of proteins. These combinations of cholesterol and proteins are called lipoproteins.

There are two main types of lipoproteins – LDL (low-density lipoprotein) and HDL (high-density lipoprotein). The lower the density of the lipoprotein, the more fats it contains.

  • Low-density lipoproteins – sometimes called LDL cholesterol (bad cholesterol) – carry cholesterol from the liver, through the bloodstream, to the cells.
  • High-density lipoproteins – sometimes called HDL cholesterol (good cholesterol) – return the extra cholesterol, that isn’t needed, from the bloodstream to the liver. HDL cholesterol is a ‘good’ type of cholesterol because it removes the bad cholesterol from the bloodstream rather than depositing it in the arteries.

Triglycerides

Triglycerides are another type of fatty substance in the blood. They are found in foods such as dairy products, meat and cooking oils. They can also be produced in the body, either by the body’s fat stores or in the liver. People who are very overweight, eat a lot of fatty and sugary foods, or drink too much alcohol are more likely to have a high triglyceride level.

 Cholesterol, triglycerides and the risk of coronary heart disease and stroke

People who have a high total cholesterol level have a higher risk of coronary heart disease than those with lower levels. The risk is particularly high if you have a high level of LDL cholesterol and a low level of HDL cholesterol (the good cholesterol).

People with a high triglyceride level have a greater risk of coronary heart disease and stroke than people with lower levels. The risk is even greater if you also have other risk factors – for example, if you have a high cholesterol level, or you smoke, or you have diabetes or high blood pressure. (A risk factor is something that increases your chances of getting a disease.)

What part does cholesterol play in coronary heart disease?

Coronary heart disease is caused when the coronary arteries (the arteries that supply the heart muscle with oxygen-containing blood) become narrowed by a gradual build-up of fatty material within their walls. This condition is called atherosclerosis, and the fatty substance is called atheroma.

Atheroma develops when the level of the ‘bad’ LDL cholesterol is too high. On the other hand, HDL cholesterol is ‘good’ because it removes excess cholesterol from the circulation, and helps to protect against coronary heart disease.

 The aim is to have:

  • a low total cholesterol level
  • a low level of LDL cholesterol, and
  • a high level of HDL cholesterol.

 Eating a healthy diet can help to improve your cholesterol levels. The most important thing is to reduce the total amount of fat in your diet, especially saturated fat (animal fat).

When does high blood cholesterol level matter?

A high level of cholesterol is one of the most important risk factors for coronary heart disease. The other major risk factors are:

  • having diabetes
  • smoking
  • having high blood pressure
  • not being physically active enough
  • being overweight or obese
  • having diabetes
  • having a family history of premature coronary heart disease. (This means if a close blood relative of yours developed coronary heart disease before the age of 55 for a man, or 65 for a woman.)

There is also a greater risk of heart attacks among people who have familial hyperlipidaemia – an inherited condition in which the blood cholesterol level is very high.

What causes high blood cholesterol?

The most common cause of high blood cholesterol levels in people is eating too much fat, especially saturated fat. However, some people have high blood cholesterol levels even though they have a healthy diet.

Some people have high cholesterol levels as a result of an underactive thyroid gland, long-term kidney problems, or having too much alcohol. Also, about 1 in 500 people have high cholesterol levels because of the inherited condition familial hyperlipidaemia.

How can physical activity help improve my cholesterol level?

Doing regular physical activity – for example, brisk walking or cycling – for 30 minutes a day on at least five days a week can help improve your cholesterol level. You can do the 30 minutes all in one go, or in shorter bouts of at least 10 minutes a time. Being active can increase the level of HDL cholesterol (the ‘good’ cholesterol).

It can also help lower your blood pressure, help you to maintain a healthy weight and reduce your risk of getting diabetes. To get the most benefit, you need to be active enough to make you feel warm and slightly puffed but still able to have a conversation. It’s important to build up gradually the amount of activity that you do.

Here are some examples of how you can start to include physical activity in your daily routine.

  • Walk rather than use the vehicle.
  • Get off the bus or train a stop early and walk the rest of the way.
  • Climb the stairs rather than use the lift.

How can healthy eating help improve my cholesterol level?

Eating a healthy diet can help reduce your cholesterol levels by over 10%.8 However, some people find that healthy eating can have a greater effect on their cholesterol level than other people.

Choosing healthier fats

Foods containing fat are made up of a combination of saturated fats, monounsaturated fats and polyunsaturated fats.

To help improve your cholesterol level you need to do the following.

  • Cut right down on saturated fats and replace them with monounsaturated fats and polyunsaturated fats.
  • Reduce the total amount of fat you eat – especially if you are overweight. (This is because fat is also very high in calories.) For example, cut down on foods such as pastries, crisps and biscuits, and replace them with healthier alternatives such as fruit or vegetables. Or, at mealtimes, cut down on the amount of fatty foods you eat by filling up with starchy foods such as bread, pasta or rice instead – particularly the wholegrain versions of these foods.
  • Cut down on foods containing trans fats. This means cutting down on processed foods such as cakes, biscuits and pastries.
  • Eat oily fish regularly. Oily fish provide the richest source of a particular type of polyunsaturated fat known as omega-3 fats that can help to lower blood triglyceride levels, help prevent the blood from clotting, and help to regulate the heart rhythm.

How do the different types of fat in foods affect my cholesterol levels?

Saturated fats can increase total cholesterol and LDL cholesterol. LDL cholesterol increases the risk of fatty deposits developing in your arteries.

Monounsaturated fats can lower the LDL level and do not lower the level of HDL cholesterol (the ‘good’ cholesterol).

Polyunsaturated fats are an essential part of the diet. They can help lower LDL cholesterol (which is a good effect), but they also lower HDL cholesterol (the ‘good’ cholesterol).

Oily fish contains a particular type of polyunsaturated fat called omega-3 fats. These can help to reduce triglyceride levels in the blood.

Other ways to improve your cholesterol levels

Eating a high-fibre diet

Eating foods that are high in ‘soluble fibre’ – such as porridge, beans, pulses, lentils, nuts, fruits and vegetables – can help lower cholesterol. A high-fibre diet also helps to fill you up – making you less likely to snack on fattening foods.

What about the cholesterol found in foods?

The cholesterol found in some foods – for example eggs, liver and kidneys, and some types of seafood such as prawns – does not usually make a great contribution to the level of cholesterol in your blood. If you need to reduce your cholesterol level, it is much more important that you eat foods that are low in saturated fat.

Will eating sterol-enriched foods help reduce my cholesterol level?

There is evidence that substances called ‘plant sterols’ and ‘stanols’ – which are added to certain foods including margarines, spreads, soft cheeses and yogurts – may reduce blood cholesterol levels. They may be helpful for people who cannot take cholesterol-lowering drugs, or for those who still have high cholesterol levels even though they have already made changes to their diet. They can also be taken with cholesterol-lowering drugs.

Will I need to take medication?

Whether you need to take cholesterol-lowering drugs or not depends not just on your total cholesterol, HDL and LDL levels, but also on your overall risk of coronary heart disease.

Doctors prescribe cholesterol-lowering medicines for people who are at greatest overall risk of suffering from coronary heart disease. So your doctor is likely to prescribe cholesterol-lowering drugs, such as statins:

  • if you have diabetes
  • if you have high blood cholesterol levels, particularly if you also have other risk factors – for example, if you have high blood pressure or you smoke
  • if you have already had a heart attack or stroke
  • if you have angina or peripheral arterial disease, or
  • if you have had bypass surgery or angioplasty.

The higher your risk of coronary heart disease, the more likely it is that your doctor will recommend cholesterol-lowering drugs.

Even if you don’t have high cholesterol levels, your doctor may still feel that you will benefit from taking cholesterol-lowering drugs, such as statins, if you have a combination of major risk factors for coronary heart disease. These include, for example, if you have high blood pressure, if you smoke, if you have a strong family history of coronary heart disease (if a close relative developed coronary heart disease before the age of 55 for a man, or 65 for a woman). Your age is also relevant as your risk of coronary heart disease and stroke usually increases with age. Your sex is relevant too as women’s risk of heart disease lags about 10 years behind that of men.

There are various sets of guidelines to help doctors decide whether to recommend that you take cholesterol-lowering drugs. All of this means that people with a wide range of cholesterol levels may be treated with cholesterol-lowering drugs. For example, someone with low cholesterol levels but with several major risk factors might be given statins. On the other hand, a person with a high cholesterol level but with no other risk factors might not be treated with cholesterol-lowering drugs.

Cholesterol-lowering medicines are a long-term and effective treatment. However, it is important to lower your overall risk of coronary heart disease as much as possible. This includes getting your lifestyle right as well as taking cholesterol-lowering medicines. Stopping smoking, eating a healthy diet, taking regular physical activity, controlling your weight and making sure your blood pressure is normal, will all help.

How can medication help?

Statins

The main type of drugs used to reduce cholesterol levels is statins. Examples of statins are simvastatin, pravastatin, rosuvastatin, atorvastatin and fluvastatin. Statins can reduce total cholesterol levels by more than 20%, and LDL levels by more than 30%. Overall, they can reduce the risk of having a heart attack or stroke by about a quarter.

Statins can help to stabilise the atheroma (the build-up of fatty deposits) within the lining of the arteries and so reduce your risk of a heart attack or stroke. This is why most people who are at high risk of coronary heart disease, stroke or peripheral arterial disease or who have diabetes are prescribed a statin drug even if they have a normal cholesterol level.

Many of these have been tested in long-term trials that have looked not just at the cholesterol levels they produce but also at their effect on health and long-term safety. For people who are already at high risk of having a heart attack, the benefits of taking statins are likely to outweigh the possible risk of side effects.

Your doctor will choose the best statin and dose for you, depending on your medical history and your target cholesterol level. Simvastatin is no longer patented, which means that it is much cheaper than other statins. So, if you’re taking a statin other than simvastatin, your doctor may suggest that you swap to simvastatin. This is sensible because it can work well for most people. However, if your doctor is planning to change your statin, you should have a blood cholesterol test before and after the change to make sure that simvastatin works well for you.

Statins are not suitable for people who have liver disease or for women who are pregnant or breastfeeding. Most statins should be taken in the evening, because our bodies make most of our cholesterol at night. However, you can take atorvastatin and rosuvastatin at any time.

If you are taking the statin drug simvastatin, you should avoid drinking grapefruit juice or eating grapefruit. However, if you’re taking another statin, such as atorvastatin, you could have small quantities of grapefruit juice (or the grapefruit).

Possible side effects of statins

Unwanted effects of statins can include feeling sick, being sick, diarrhoea and headaches.

A rare side effect of statins is inflammation of the muscles (myositis). If you have any unexpected muscle pain, tenderness or weakness, you should tell your doctor. He or she may change the type of statin you are taking, or the dose. 

Other cholesterol-lowering drugs

There are other types of drugs which can be used to lower blood cholesterol levels. These are:

  • fibrates
  • drugs which bind bile acids
  • nicotinic acid drugs, and
  • ezetimibe.

These drugs all act by preventing the intestine from absorbing cholesterol. 

Fibrates

Examples of fibrates include bezafibrate, ciprofibrate, fenofibrate and gemfibrozil. Fibrates are useful for people who have a high level of both blood cholesterol and triglycerides. You will not usually be given fibrates if you are also taking statins, except under strict medical supervision. You should not use fibrates during pregnancy, or if you have liver or kidney disease.

Drugs which bind bile acids

These drugs (which are also called ‘bile acid binding drugs’) include cholestyramine and colestipol. They work by binding bile acids which the liver makes from the cholesterol in the blood, and preventing the bile acids from getting reabsorbed into the bloodstream.

They come in powder form, in sachets. You have to soak some types in fruit juice before you take them. Others are already mixed with fruit flavouring and you just need to add water. You should take these drugs immediately before or during a meal. They may make you feel fuller than usual at first, but most people gradually get used to this.

These drugs are not absorbed into the body, so they can also be used safely by children and pregnant women.

Possible side effects

Some people who take these drugs may get heartburn or constipation, but this is more likely with larger doses.

Nicotinic acid drugs

Nicotinic acid and acipimox are drugs that help to lower LDL levels and increase the level of ‘good’ HDL cholesterol.

Ezetimibe

Ezetimibe is another type of cholesterol-lowering drug. It can be used along with a statin, or people who cannot take statins can take ezetimibe on its own. Ezetimibe helps to lower blood cholesterol levels by preventing the small intestine from absorbing cholesterol.

Ezetimibe can help reduce LDL cholesterol by about 18%, and if it is combined with low-dose statins it can be even more effective.

Possible side effects

Unwanted effects of ezetimibe include headaches, pain in the abdomen and diarrhoea.

Drugs which reduce triglyeride levels (fish oils)

If you regularly eat oily fish, control your weight, and limit how much alcohol you have and yet you still have a high triglyceride level, your doctor may prescribe fish oils for you.

If you are taking fish oils which you have bought over the counter, tell your doctor about them so that he or she can make sure that they don’t interfere with any other drugs you are taking such as warfarin.

 

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