What is heart disease?
The heart is a muscular pump that constantly pumps blood around your
body. Because it works very hard it needs a good blood supply to its
muscles, which is provided by the coronary arteries.
Coronary
heart disease is a disorder of the heart that results from the narrowing
of the arteries that supply blood and nutrients to the heart muscle.
Symptoms include angina or chest pain when exercising, which eases
when you rest. This may not appear until the artery has narrowed by
more than 70%
Coronary
heart disease can also cause heart failure. This occurs when the heart
muscle cannot pump the blood around the body quickly enough, so it
begins to pool and causes breathlessness and swollen ankles. You may
also experience irregular heartbeats that result in palpitations and
breathlessness.
There
are other types of heart disease, which have other causes, including
those that some people are born with. Heart disease can also result
from problems with the heart muscle or valves rather than the arteries.
What are the risk factors for heart disease?
Risk factors for developing heart disease include:
• Raised cholesterol - this may be genetic, as some families
carry genes for raised cholesterol levels.
• Smoking.
• High blood pressure.
• Diabetes.
• Obesity.
• Stress.
• Lack of exercise.
• Gender - more men than women get coronary heart disease.
• Age - it becomes more common the older we get.
The more risk factors you have, the greater your chance of developing
heart disease.
How is cholesterol related to heart disease?
A certain form
of cholesterol called low-density lipoprotein (LDL) cholesterol causes
fat, known as plaques, to deposit on the walls of the arteries. This
builds up gradually over the course of 20 or 30 years, usually beginning
in early adulthood. As the plaques deposit, the walls of the arteries
harden and weaken, reducing the flow of blood through the artery.
The extent of the problem and how quickly it develops depends on the
amount of low-density lipoprotein (LDL) cholesterol in the blood.
The
build up of plaque eventually damages the lining of the artery, causing
blood cells called platelets to stick to the surface in the form of
a clot. This can narrow the artery considerably and cause a form of
chest pain known as unstable angina. This condition may mean that
you can only walk a few steps before feeling chest pain and you should
see you doctor at this point.
Sometimes
the plaque becomes covered by scar tissue, which can rupture under
any sudden stress. This creates a wider area of damage to the wall
of the artery. A much larger clot will then form, leading to complete
blockage.
This
means that the blood supply to the heart muscle is completely cut
off. This results in the death of the muscle and causes a heart attack.
It usually causes severe chest pain and can be fatal.
Has the link between
high cholesterol and heart disease been proven?
Yes. After World War Two, America experienced what has been referred
to as an epidemic of heart disease. Men approaching their 50s and
60s were dying like never before and the American government wanted
to know why.
It was decided that a study of the health of ordinary people in their
30s would be carried out over 20 years to gather data. In 1948 the
longest running major epidemiological project in medicine began in
a small town called Framingham, near Boston in the US.
In all, 5,209 healthy residents of Framingham (one in five of the
town's population), between the ages of 30 and 62, who showed no sign
of heart disease agreed to take part in the study. Every two years
participants underwent a complete phyical examination.
These examinations found a strong link between coronary heart disease
and raised cholesterol. In 1961, researchers found that the higher
the level of cholesterol in the blood, the higher the risk of having
a heart attack.
The study has resulted in over 1,000 reports and a myriad of important
data. In 1987 high blood cholesterol levels were found to correlate
directly with risk of death in young men, while in 1988 the study
showed that the 'good' cholesterol, high density lipoprotein (HDL),
protected against heart disease.
In 1997 a report on the cumulative effects of smoking and high cholesterol
on the risk of developing plaques on the walls of the arteries (atherosclerosis),
which cause heart attacks and strokes was issued.
The biggest drawback of the study is its lack of ethnic diversity,
which means that the results cannot be applied to non-white people.
At present, 1,000 non-white residents of Framingham are being recruited
for a new section of the study and 5,124 children and spouses of original
participants joined the study in 1971.
It is hoped that a third generation of family members will be recruited
eventually, which will enable the tracking of genetic diseases. Only
1% of the surviving participants dropped out of the study and, while
a quarter have moved elsewhere,most still attend for their check ups.
The study also showed the importance of other risk factors such as
smoking, high blood pressure and diabetes. Over 50 years on, the study,
which has cost $43 million so far, is still ongoing and has yielded
some of the most influential results ever.
What is the relationship
between diet and cholesterol?
Cholesterol is a fatty substance found in every cell in the body.
It is produced by your liver in sufficient quantities for your body's
requirements. If, however, you eat certain foods high in cholesterol,
the level in your blood rises.
Animal and dairy foods contain high levels of saturated fat, which
raises the level of 'bad' cholesterol in your blood. Therefore the
more of these foods you eat the higher your risk of coronary heart
disease. For this reason it is worth reducing the level of animal
and dairy fats in your diet. By modifying your intake of fat, calories
and carbohydrates the level of cholesterol in your blood can be reduced.
Food that are high in saturated fats:
• Red meat.
• Hard cheeses.
• Butter.
• Cream.
• Full-fat milk.
• Yogurt.
• Lard. 
It is recommended that you use polyunsaturated or monounsaturated
fats in your diet instead as these will reduce the amount of cholesterol
in your blood. Foods that are high in polyunsaturated fats include
vegetables and fish oils. Monounsaturated fat is found in olive oil.
Steps to healthy eating:
• Reduce the amount of fat in your diet.
• Use vegetable oils instead of animal fats.
• Eat more fresh fruit and vegetables.
• Go on a sensible weight-reducing diet if necessary. |
