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The
New theories:
1. Oxidation of LDL
Toxic metals such as aluminium and lead, as well as
iron and copper, when in excess, initiate free-radical
production. These free-radicals oxidise low density
lipoproteins (LDL), which are ingested by cells of your
immune system called macrophages.
These macrophages soon
become stuffed with oxidised LDL and form new cells
called foam cells. These foam cells then clump together
leading to fatty deposits on the arterial walls which
is the beginning of atherosclerosis.
2. Inflammation
When your immune system is activated, inflammation takes
place. This means that your body is heating up to defend
itself against some impending threat which might be
a parasite or bacteria, an environmental toxin, food
allergy or any other source of danger.
Sometimes the immune
system gets confused and attacks your own body, for
example in rheumatoid arthritis and other auto-immune
diseases. in the case of ischaemic heart disease inflammatory
cells of the immune system give off smaller cells called
'ICAMS' which are intracellular adhesion molecules.
These infiltrate the
arterial wall where they are gobbled tip by foam cells
which in turn release oxidants which convert LDL to
oxidised LDL. Oxidised LDL accumulates leading to the
development of atherosclerosis. A blood test measuring
c-reactive protein will some indication whether an inflammatory
process is taking place in your body.
3. Insulin
Until recently insulin was thought to be solely responsible
for glucose and fat metabolism. What we know now is
that raised insulin levels have a number of adverse
metabolic and physiological consequences including elevated
cholesterol and LDL levels, increased oxidative stress,
decreased HDL and high blood pressure.
If you are overweight,
feel tired after a carbohydrate meal such as pasta or
rice and have difficulty saying no to a packet of biscuits
once you have commenced the first biscuit, chances are
you have high insulin levels. A simple blood test measuring
glucose and insulin before and after a carbohydrate
challenge will inform you of the presence of this problem.
4. Lipoprotein (a)
Linus Pauling has put forward the theory that
more lipoprotein (a) is made when vitamin C is deficient
which then travels to arterial walls depositing itself
there. These lipoprotein (a) molecules thicken arterial
walls, thereby resulting in cardiovascular disease.
For survival of the
species, it makes more sense to die from a heart attack
after reproduction, than to die from scurvy before reproduction.
5. Homocysteine
This protein has achieved major prominence as one of
the primary new players in the cause of heart disease.
There is now evidence that raised homocysteine levels
are associated with ischaemic heart disease in 10-20
per cent of cases.
In fact some studies
have indicated that the risk of coronary artery disease
increased by 70 per cent for each 5uml increase in homocysteine.
Homocysteine is an amino acid and it is produced as
the body processes proteins. Normally homocysteine is
metabolised to a harmless by-product.
In order to do this,
certain vitamins are necessary and these are vitamins
B6, B1, and folic acid. These vitamins are derived from
leafy green vegetables and fruit and it comes as no
surprise that up to 40 per cent of the population may
be deficient in these, leading to raised homocysteine
levels.
Homocysteine is a potent
inducer of atherosclerosis and causes visible damage
to blood vessels at a very early stage. Certain individuals
also have a genetic propensity to elevated homocysteine.
6. Vitamin E
Low rates of ischaemic heart disease are associated
with high dietary vitamin E levels. Vitamin E is thought
to play a role through inhibition of oxidation of LDL.
In a large experiment
performed in the United Kingdom supplements of vitamin
E, given in levels exceeding those that may be obtained
from dietary sources alone, significantly reduced the
incidence of ischaemic heart disease and heart attacks.
This was achieved in
some patients who had advanced atherosclerotic lesions
indicating that if indeed oxidation of LDL is the culprit
this can be reversed by high dose antioxidants.
7. Low magnesium
Magnesium deficiency is associated with all the manifestations
of heart disease including irregular heart beat, increasing
atherosclerosis, spasm of the arteries, raised blood
pressure and heart attack.
Magnesium insufficiency
is not something that is generally thought of as important
or even likely. However the foods that are highest in
magnesium - vegetables (especially legumes and dark
green vegetables), whole grains and nuts are not major
constituents of the Australian diet.
Nutrients that are
high in the diet including saturated fat, sugar, salt
and alcohol, all increase the dietary need for magnesium.
Aging and stress also augment magnesium requirements.
Magnesium supplementation has been shown to lower blood
pressure and prevent the development of atherosclerosis
by reducing total cholesterol and raising HDL.
In brief, oxidised
LDL, inflammation, raised insulin levels, elevated lipoprotein
(a), excess homocysteine and reduced magnesium levels
are all risk factors for the development of heart disease.
This explains why some
individuals with normal cholesterol are in danger of
having a heart attack and that other factors need to
be considered when you have your cardiovascular status
evaluated.
Index
page
| New theories | Preventing
heart disease | The
healthy diet
'Wonder
nutrients' for the cardiovascular system | Opening
your heart
Protecting
your prostate | Losing
your hair? |
Antioxidants |Summary
Bondi
Family Health Centre
Phone 02 9365 1333
Int: 612 9365 1333
260a Bondi Road
Bondi NSW 2066
AUSTRALIA
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