at said:http://www.ravnskov.nu/cholesterol.htm (author's web site)
"The Cholesterol Myths : Exposing the Fallacy that Saturated Fat and Cholesterol
Cause Heart Disease" by Uffe Ravnskov was first published January 1997.
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Dr. Ravnskov is a serious, published scholar and medical scientist.
He attempts to make the case that cholesterol is unrelated to heart
disease.
The cornerstones of his argument are inconsistent benefit seen in
intervention trials and ostensible lack of association between cholesterol
levels and degree of atherosclerosis.
I believe that his conclusions are in error, owing to a fatal flaw in his
data analysis.
He has restricted his data analysis to the literature related to populations
with high cholesterol levels (i.e. above 150-160) and to dietary
interventions
which are ineffective in driving cholesterol levels down to below 150-160.
The following facts remain:
1. Atherosclerosis is virtually unknown in populations with blood
cholesterols below 150-60.
2. Atherosclerosis is uniformly low in populations on very low fat
diets.
3. There is a clear statistical relationship between incidence of clinically
significant coronary artery disease and pre-morbid serum cholesterol.
This is different than in correlating the extent of atherosclerotic lesions.
The reason for this disparity is because once atherosclerosis is intiated
(fatty streak progresses to a small atheroma which progresses to a larger
atheroma), other factors are more important to the progression of the
atheroma than serum cholesterol, per se. This is where homocysteine
and free radicals and all that other good stuff may come in.
But if serum cholesterol is below a critical threshold level (operationally
around 150-60) then there is no fatty streak and no atherosclerosis.
And when you drive cholesterol levels down by more than 20%, you
see stabilization and/or improvement in pre-existing lesions in many
people.
Most harmful to Ravnskov's thesis are the statin data. Consistently,
the statin studies show improved cardiovascular disease, lower incidence
of heart attacks, lower incidence of strokes, improved overall mortality,
no increased risk of cancer or hemorrhagic stroke, etc. This is
also consistent with the diet data, where moderate fat restriction
did not lower cholesterol dramatically and where there were inconsistent
health benefits. But marked fat restriction consistently improved
blood pressure, insulin, weight, heart disease symptoms, pre-existing
coronary lesions, and overall mortality.
So Ravnskov attempted to explain away the statin data by claiming that
the effects of statins had nothing at all do do with cholesterol.
His arguments were as follows:
1. Statins effective for women, "surprising because ...a high cholesterol
is not a risk factor for women."
2. Old individuals protected as much as younger; "high cholesterol
not a risk factor in people over 50"
3. Stokes reduced also; "no studies showed a high cholesterol was
a risk factor for stroke."
4. Patients with coronary disease protected, though high cholesterol
only a weak risk factor for people who already had a coronary."
5. Statins protected whether cholesterol high or low, "though most
studies showed a normal or low cholesterol is no risk factor
for heart disease."
The problems with these arguments (as with Dr. Ravnskov's whole thesis)
is in his definition of "high cholesterol." (But I should also add that
studies certainly do exist to correlate cholesterol with stroke risk).
What Ravnskov call's "normal" cholesterol just means "average" cholesterol.
What the Stanford U Med School's "Heart Healthy" book calls a
healthy cholesterol is one below 160, at which point heart disease
becomes an unimportant problem. No cholesterol above 150-160,
little or no risk of heart disease.
So cholesterol is critically important, essential, and, by my definition
causal to heart disease. If you can keep your cholesterol below 150
with whatever diet you like, you will have a very low risk of heart disease.
I'd maintain that a low fat/high veggie/high fiber/low sugar/low salt
diet is the best way to do this, because of other health benefits
(lower blood pressure, lower insulin, lower cancer risk, more
folate and B6, etc.).
This does not deny the fact that there are many mitigating factors
in people with high (i.e. above 150-60) cholesterols:
If you've got a high total cholesterol, it's helpful to have low
homocysteine levels, to have high HDLs, maybe to have low
serum iron, to take aspirin so that your platelets don't aggregate,
to eat grapes, to take a drink or two per day, to exercise aerobically,
to take vitamin E, and all sorts of things.
But people on quasi-vegetarian diets (moderate low fat meat is probably not
a problem and may help avoid problems with extremes of vegetarianism)
have low cholesterols, low heart disease, low cancer, and favorable
longevity. Won't work for everyone, but will work for a great many.
I agree with Ravnskov that moderately low fat diets don't seem to
do a whole lot of good and that, once you are in the elevated cholesterol
range (above 150-160) there are other factors as important or more
important than cholesterol per se. But - once again - no elevated
cholesterol, virtually no heart disease. It's really just that simple.
And nothing else save lowering cholesterol has been shown to be
effective in reversing heart disease, once established.
he following data from the MRFIT Study clearly show the linear trend between
serum cholesterol and CHD risk:
Mean Serum CHD deaths Relative
Decile Cholesterol per 1000 Risk
------ ----------- ---------- --------
1 153 3.16 1.00
2 175 3.32 1.05
3 187 4.15 1.31
4 198 4.21 1.33
5 208 5.43 1.72
6 216 5.81 1.84
7 226 6.94 2.20
8 238 7.35 2.33
9 253 9.10 2.88
10 296 13.05 4.13
So, even though there are other risk factors for CHD when cholsesterol
is above
150, cholesterol is still a major, perhaps the major, risk factor.
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