What is cholesterol?
Cholesterol is a soft, waxy substance found among the lipids (fats) in the bloodstream and in all your body's cells. It is an important part of a healthy body because it is used for the formation of cell membranes, some of the bodies hormones. It is a component of the nervous system and also a valuable source of energy. However, a high level of cholesterol in the blood is a major risk factor for coronary heart disease, which can lead to heart attack. Cholesterol and other fats cannot be dissolved in the blood. They have to be transported to and from the cells by special carriers called "lipoproteins". While there are several kinds of these lipoproteins, the ones to focus on are low-density lipoprotein ("LDL") and high-density lipoprotein ("HDL").

Good and Bad cholesterol: About one-third to one-fourth of all blood cholesterol is carried by HDL. HDL tends to carry cholesterol away from the arteries and back to the liver, which is the main source of cholesterol. HDL removes excess cholesterol from plaques and thus slows their growth. HDL cholesterol is known as "good cholesterol" because a high HDL level has proven to protect against heart attack and stroke. However, the opposite is also true -- a low HDL level indicates a greater risk to the body. Low-density lipoprotein (LDL) is the major cholesterol carrier in the blood. If too much LDL cholesterol circulates in the blood, it can slowly build up in the walls of the arteries feeding the heart and brain. Together with other substances it can form plaque, a thick, hard deposit that can clog those arteries. A clot (thrombus) that forms near this plaque can block the blood flow to part of the heart muscle and cause a heart attack. If a clot blocks the blood flow to part of the brain, a stroke results. A high level of LDL cholesterol reflects an increased risk of heart disease. That is why LDL cholesterol is called "bad cholesterol". Lower levels of LDL cholesterol reflect a lower risk of heart disease.

Causes of hyper-cholesterolaemia
The causes of hyper-cholesterolaemia may be primary (i.e. genetic) or secondary. Genetic hypercholesterolaemia includes familial hyper-cholesterlaemia, polygenic or familial combined hyper-lidaemia. Secondary hyper-cholesterlaemia is due to diabetes mellitus, obesity, having an under active thyroid, liver disease, kidney disease and also some drugs.

Diagnosis
The presence of xanthelamas (deposits of cholesterol in the skin around the eye), tendon xanthomas (swelling on the tendons of muscles, typically the Achillies' heel, on the back of the hands or on the elbows), or early corneal archus (a white ring found in the outer part of the cornea of the eye) may suggest hyper-cholesterolaemia, but the only way to be absolutely sure is to have your blood cholesterol levels measured. Cholesterol levels are quite variable within an individual. Cholesterol levels may vary with age, sex, season, menstrual cycle, pregnancy, illness and some drugs.

Treatment
The reasons for treating hyper-cholesterolaemia is to reduce the risk of coronary heart disease, stroke or even sudden death. Over the last 20 years, the benefits of treating hypercholesterolaemia have been clearly demonstrated. The main treatment is a change of diet and a change of life style which includes low fat diet, less salt intake, more fresh fruit, vegetable, high fibre diet, avoid animal fat, avoid red meat, give up smoking, loose weight and increase your levels of physical activity.

If somebody is at high risk, they may need to take medication. Statins, Fibrates and other cholesterol absorption inhibitors are the drugs of choice. However you should consult with a doctor before starting medication.

Reducing cholesterol reduces the risk of heart disease, increases expectation of life, and does not increase the likelihood of suffering from other diseases. Understanding the facts about cholesterol will help you to take better care of your heart and live a healthier life, reducing your risk for heart attack, stroke, and even sudden death. Therefore it is time to reduce your cholesterol to ensure a healthy heart!

Dr Md Habibe Millat MBBS FRCS(Edin) is a Senior Specialist Registrar, Department of Cardiothoracic Surgery, Cork University Hospital, Ireland.