What is cholesterol?

Cholesterol is a fatty substance or lipid, which is found in every cell of the human body. It is very important as it makes up part of the structure of the membranes (walls) of every cell in the body. It is also involved in the manufacturing of hormones and the production of energy.

Even though the body is able to manufacture enough cholesterol on its own, additional cholesterol is absorbed from the foods we eat.

I always assumed cholesterol was a bad thing. Was I wrong?

Yes. There are 'good' and 'bad' forms of cholesterol. Because most people only hear about 'bad' cholesterol, it is important to make the distinction because cholesterol is an essential element of all living cells.

In the bloodstream, cholesterol is attached to proteins and is transported in the form of complex molecules called lipoproteins.

HDL (high density lipoprotein) is known as 'good' cholesterol because a high level of HDL helps to protect against atherosclerosis, which can lead to many heart problems such as heart attack and stroke. HDL works by removing cholesterol from the artery walls.

LDL (low density lipoprotein) is considered 'bad' cholesterol because it deposits cholesterol plaques onto the walls of the arteries. Therefore when LDL levels are high, atherosclerosis (hardening of the arteries) or cardiovascular disease can develop. This is especially the case in somebody who smokes or has high blood pressure (hypertension) or diabetes. (Find out more about atherosclerosis).

Triglycerides are another type of fat, which are carried in the blood by very low density lipoproteins. A high triglyceride level may accompany a high LDL level.

A high total cholesterol level (above 6mmol/litre) is associated with increased risk of cardiovascular disease. However, it is recommended that your total cholesterol should not be any greater than 5mmol/litre.


How can I raise my 'good' cholesterol level and lower my 'bad' cholesterol level?

The same measures that lower 'bad' cholesterol levels can increase 'good' cholesterol levels.

  • Maintain a healthy and varied diet. While fat should not be left out of the diet altogether, try to avoid saturated fats such as those found in fatty red meat or full-fat dairy products.
  • Regular exercise is extremely important. It is associated with an increased ability to clear fat particles from the blood stream after meals. This is especially important if you have eaten a meal with a high fat content. Exercise increases the levels of HDL (‘good’ cholesterol) in the blood, and is thought to lower the levels of LDL ('bad' cholesterol).
  • Stop smoking. Smoking is known to lower HDL (‘good’ cholesterol). This can be reversed if you quit smoking.
  • Some people may also need to take cholesterol-lowering medication.

I heard that alcohol can help if you have high cholesterol. Is this true?

Moderate use of alcohol is thought to be linked with HDL ('good' cholesterol). However the benefit is not great enough to recommend drinking alcohol in order to reduce cholesterol levels or the chances of heart disease.

While incidences of heart disease are lower in moderate drinkers than non-drinkers, increased alcohol consumption can lead to a number of problems such as high blood pressure and alcoholism.

Therefore if you drink already, do so in moderation. If you don't drink, alcohol is definitely not recommended to reduce the risk of heart disease. Let’s be honest: if alcohol consumption was a really useful way of reducing heart disease, we in Ireland would not have the very high levels of heart disease which are now prevalent.

What are the symptoms of high cholesterol?

Unfortunately most people don't realise that they have a high cholesterol level until another condition related to it, such as atherosclerosis, rears its head.

Atherosclerosis can lead to angina (pain in the chest), heart attack or heart failure, pains in the legs due to peripheral vascular disease, or stroke.

As a result it is essential that you maintain a healthy diet and take part in regular exercise to avoid the possibility of developing a high cholesterol level. People over the age of 20 should be tested for cholesterol every few years by their doctor.

In very rare cases high cholesterol levels are inherited. Known as familial hypercholesterolemia, this can be treated by your doctor. It is therefore useful that you know your family's health history.

What can I do if I have high cholesterol?

Having a high cholesterol level is usually a long-term problem. However, switching to a healthy diet that is low in saturated fat and increasing the amount of exercise you do, can in some people lower cholesterol levels within six weeks. The problem for many people isn't switching to a new, healthier lifestyle but maintaining it in the long term.

If lifestyle measures are not enough to lower your cholesterol to safe levels, medication may also be needed. The main type of drugs used to treat high cholesterol are called statins; these can be prescribed by your doctor. These drugs stop the body from making cholesterol, reducing the level in the blood and preventing risk of cardiovascular disease. Cholesterol-lowering drugs are most effective when used together with a healthy diet and exercise.

For more information and advice on high cholesterol, visit the Heart Disease Clinic.

Reviewed: December 12, 2006