Cholesterol

What is cholesterol?

Cholesterol is a chemical that is made in the liver from fatty foods that you eat. A certain amount of cholesterol is present in the bloodstream.

You need some cholesterol to keep healthy. However, if you have a high blood cholesterol level, you have an increased risk of developing atheroma. A build up of atheroma can cause heart diseases such as angina and heart attacks, stroke, transient ischaemic attack (TIA or 'mini-stroke'), and peripheral vascular disease (narrowing of the arteries to the legs).

Patches of atheroma are like small fatty lumps which develop within the inside lining of arteries (blood vessels). A patch of atheroma makes an artery narrower, which may reduce the blood flow.

Over time, patches of atheroma can become larger and thicker. The common cause of angina is due to atheroma which narrows one or more of the arteries that supply blood to the heart muscle.

Sometimes a blood clot (thrombosis) forms over a patch of atheroma, and completely blocks the blood flow. Depending on the artery affected, this can cause a heart attack, a stroke, or other serious problems.

Everybody has a chance of developing atheroma. However, you are more likely to develop thick patches of atheroma if you have certain risk factors which include:

• smoking.
• hypertension (high blood pressure).
• high cholesterol level.
• diabetes.
• obesity.
• lack of exercise.
• an unhealthy diet.
• a strong family history. This means if you have a father or brother who developed heart disease or a stroke before they were 55, or in a mother or sister before they were 65.
• being male.
• ethnic group (for example, southern Asians in the UK have an increased risk.)

Some risk factors are more 'risky' than others. For example, smoking causes a greater risk to health than a lack of exercise. Also, risk factors interact. So, if you have two or more risk factors, your health risk is much more increased than if you just have one.

Should I have my cholesterol level checked?

In certain situations it is useful to know your cholesterol level to get a better idea of your health risk, and if necessary, to plan treatment to reduce your health risk. So, a cholesterol blood test is commonly advised if:

• you have other significant risk factors, such as diabetes or high blood pressure. A high blood cholesterol would add to your existing risk.
• you already have angina, had a heart attack, had a stroke or TIA, have peripheral vascular disease, or have another atheroma related condition.
• a very high cholesterol level runs in the family (familial hypercholesterolaemia).

The blood test is not usually advised if you are healthy, and your other risk factors are low.

What is a 'high' cholesterol level?

As a rule, the higher the cholesterol level, the greater the risk to health. As a guide, a level less than 5 mmol/l is considered 'good', and is often the target advised to aim for. However, at least half of adults in the UK have a cholesterol level above 5 mmol/l. An acceptable cholesterol level depends on whether you have other risk factors. For example:

• If you have a raised cholesterol level, and you smoke, and you have a family history of early heart disease, then you have quite an increased risk of developing heart disease in the future.
• But, the increased health risk is small if you have no other risk factors apart from a raised cholesterol level.

A 'risk factor calculator' is used by doctors and nurses to predict the health risk for an individual. The calculated score takes into account all your risk factors. Current guidelines advise that you should lower your cholesterol level if your score gives you a 3 in 10 risk (or more) of developing heart disease within the next 10 years, and your cholesterol level is higher than 5.0 mmol/l.

If you already have an atheroma related disease (angina, etc)
Up until recently, guidelines advised that your cholesterol level should be lowered if it is higher than 5.0 mmol/l. However, recent evidence suggests that the risk of further problems are reduced if the cholesterol level is reduced, whatever the level. Even if it is already below 5.0 mmol/l. So, you may be advised to take cholesterol lowering treatment irrespective of your cholesterol level if you: have angina; have had a heart attack; have had a stroke or a TIA; have peripheral vascular disease; have another atheroma related condition.

What causes high cholesterol?

• In most people, your cholesterol level reflects the amount of fat that you eat. This is not the full story as different people who eat the same amount of fat can make different amounts of cholesterol. However, in general, if you eat less fat your cholesterol level is likely to go down.
• In some people a high cholesterol level is due to another condition. For example, an underactive thyroid gland, obesity, drinking a lot of alcohol, and some rare kidney and liver disorders can raise the cholesterol level.
• In a small number of people a very high level of cholesterol runs in the family due to an inherited genetic problem. One example is called familial hypercholesterolaemia.

• Lose weight if you are overweight or obese. Even a modest amount of weight-loss will help. Another leaflet in this series called 'How to Lose Weight' may help.
• Eating a healthy diet can help to bring your cholesterol level down. A practice nurse or dietician may advise you on how to eat healthily. Also, another leaflet in this series called 'Healthy Eating' gives details. Briefly, a healthy diet means:
  • AT LEAST five portions of a variety of fruit and vegetables per day.
  • THE BULK OF MOST MEALS should be starch-based foods (such as cereals, wholegrain bread, potatoes, rice, pasta), plus fruit and vegetables.
  • NOT MUCH fatty food such as fatty meats, cheeses, full-cream milk, fried food, butter, etc. Use low fat, mono-, or poly-unsaturated spreads.
  • INCLUDE 2-3 portions of fish per week. At least one of which should be 'oily' (such as herring, mackerel, sardines, kippers, pilchards, salmon, or fresh tuna).
  • If you eat meat it is best to eat lean meat, or poultry such as chicken.
  • If you do fry, choose a vegetable oil such as sunflower, rapeseed or olive oil.
  • Try not to add salt to food, and avoid foods which are salty.

What treatments can lower a cholesterol level?

If you do not have an atheroma related disease (such as heart disease)

• Your doctor or nurse may suggest a 3 month trial of healthy eating (and weight loss where relevant), and then re-check your cholesterol level.
• You should aim to reduce any other 'risk factors' too. For example, smoking and lack of exercise.
• Medication to reduce your cholesterol level may be advised if your cholesterol level remains too high after 3 months. A 'statin' medicine is usually used to lower cholesterol. There are several brands of 'statin'. They work by blocking an enzyme (chemical) which is needed to make cholesterol in the liver.

If you already have an atheroma related disease (such as angina, etc)
A statin medicine is usually advised straight away to reduce the cholesterol level.

How much benefit do I get if my cholesterol level is reduced?

If you have an increased risk of developing an atheroma related disease, your risk can be reduced by up to 30% if your cholesterol level is lowered to a target level. Your GP or practice nurse will give you a 'target' level. (This is usually to below 5 mmol/l, or to a level 25-30% lower than the original level.)

If you already have an atheroma related disease, lowering the cholesterol level reduces your risk of further problems.

But remember, you should still do as much as you can to reduce any other risk factors. For example, stop smoking if you smoke, lose weight if you are overweight, eat a healthy diet, and exercise regularly.

Further help and information

Heart UK, 7 North Road, Maidenhead, Berkshire, SL6 1PE
Tel: 01628 628 638   Web: http://www.webmentorlibrary.com/gateway.asp?site=http://www.heartuk.org.uk
Committed to raising awareness of heart disease in the UK and stressing the importance of a healthy lifestyle in reducing the risk of suffering from it.

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