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What is
cholesterol?
Cholesterol, one of the groups of fats in the blood called lipids, is a
word we have all heard many times, especially, since it was established
that cholesterol was one of the most important factors in the
development of coronary heart disease (CHD).
Cholesterol is a
small molecule but despite this has been so intensively studied that by
1985 it had been the subject of 13 Nobel prizes.
In the 1980s
there was considerable reluctance to treat cholesterol abnormalities,
however in 1994 evidence became available that lowering cholesterol
reduced the incidence of heart attacks, strokes and the devlopment of angina and lowered overall mortality.
Since that time there has been unprecedented growth in the prescription
of medicines to lower cholesterol.
Is cholesterol bad for you?
Cholesterol is bad for you is a statement most people would accept. In
fact, cholesterol is essential for life and we could not live without
it, but problems arise when cholesterol levels in the blood are too
high.
How can there be
'good' cholesterol and 'bad' cholesterol? They sound contradictory but
there is a very important distinction.
"Good"
cholesterol (or HDL cholesterol) makes up about 20% of the blood
cholesterol. It is know known that high levels of HDL Choleserol gives some protection against
cardiovascular disease but low levels of HDL Cholesterol increase the
risk of cardiovascular disease.
"Bad"
cholesterol (or LDL cholesterol) can be deposited in blood vessels
leading to narrowing and blockage. If this happens in one of the coronary
(heart) arteries it can cause a heart attack or if it occurs in an
artery to the brain it can cause a stroke.
Cholesterol and
Triglyceride is a fat that always circulates in the blood, especially
after a meal high in saturated fat.
High triglyceride
levels are associated with obesity, diabetes, low HD cholesterol and
high LDL cholesterol.
Triglyceride
levels can be lowered by:
- eating less total fat
- eating less
sugar/carbohydrates
- losing weight if
necessary
- decreasing alcohol
intake
- increasing the amount
of aerobic type exercise you do
- Do not add salt to
your food without tasting it first
- Add less salt during
cooking.
- Avoid salty foods and
snacks.
- Avoid convenience
foods.
- Remember everyday foods
for example breakfast cereals and fish fingers can contain a lot
of salt so read food labels.
Some people,
(about 1 in 500), have very high levels of bad cholesterol. This runs
in families and is due to an inherited gene, which disturbs the way LDL
cholesterol is removed from the blood. This is called familial hypercholesterolaemia (FH).
Where
does cholesterol come from?
The body produces its own supply of cholesterol, mainly in the liver,
but lesser amounts can come from the diet in foods of animal origin
such as meat, dairy products and eggs. There are two groups of fat,
namely unsaturated fat and saturated fat. saturated
fat is often visible and solid at room temperature (e.g. fat on meat).
Unsaturated fat
include monounsaturated fats, polyunsaturated fats and omega-3 fats and
our diet should contain equal amounts of these. However, a Western diet
usually contains a lot more saturated fat than the other kinds of fat. To
eat healthily we not only have to reduce the quantity of fat we eat but
more importantly our diet should contain the right proportions of the
correct kind of fat.
The following
chart summarises the effects of the different groups of fats:
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