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THE
HOMOCYSTEINE
THEORY OF
CARDIOVASCULAR DISEASE
The
conventional cardiovascular disease risk factors, such as
high cholesterol levels, smoking,
and hypertension cannot completely account for why cardiovascular
diseases are the number one killer of Americans. In fact.
Dr. Johan B.
Ubbink, a cardiovascular disease
researcher at the Department of Chemical Pathology, University
of Pretoria, South Africa, recently noted that the most commonly
recognized risk factors—despite being studied exhaustively—explain
only about 50 percent of all cases of cardiovascular diseased
Clearly there are other, unrecognized causes of cardiovascular
disease. Scientists are making an effort to identify these
additional causes; many consider elevated homocysteine
to be a cause and call it the "new cholesterol."
You've
probably heard little or nothing about homocysteine. But,
if you suffer from a cardiovascular disease, there's a good
chance that your homocysteine levels are elevated. Unfortunately,
your doctor has probably never checked your homocysteine levels.
Furthermore, your doctor may not even know what homocysteine
is or how easy it is to lower its level with the B vitamins.
WHAT
IS HOMOCYSTEINE?
If
elevated homocysteine is so strongly associated with cardiovascular
disease, you may be wondering why no one has demanded that
it be banned from the marketplace or established a health
education program to get people to eat less of it. The answer
is simple: homocysteine is not
sold in stores and is not found in foods. Homocysteine, like
cholesterol, is produced naturally
in the human body. Unlike cholesterol, homocysteine is supposed
to exist only briefly before the body converts it into either
useful or harmless substances.
Protein,
particularly the essential amino
acid methionine (found in meat),
is the indirect source of homocysteine. When the body digests
and metabolizes methionine,
it produces homocysteine before either recycling methionine
or creating the final breakdown product, cystathionine.
Key
Steps in Homocysteine Formation
B12
Folate
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Protein
Methionine
Homocysteine
B6
Cystathionine
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There
are many circumstances in which homocysteine becomes a long-lived,
potentially deadly byproduct of protein metabolism. For example,
an inadequate supply of key B
vitamins "freezes"
homocysteine metabolism before it is converted to cystathionine.
When this happens, abnormally high levels of homocysteine
build up in the bloodstream and damage blood vessels. "This
condition is known as homocysteinemia.
Abnormal
levels of homocysteine can damage any of the body's blood
vessels. When the blood vessels feeding the heart are damaged;
this is called coronary artery disease. When the blood vessels
that nourish the brain are affected, stroke is the likely
outcome. And if the blood vessels of the hands or legs are
affected, peripheral artery disease is the likely consequence.
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