[First published in Art of Healing/Fit4Life on 13/10/2013]
IS HIGH CHOLESTEROL REALLY BAD?
An
estimated one in three people above 40 are on anti-cholesterol drugs or some
other cholesterol-lowering treatment. This is because about 40% of those above
40 have high cholesterol (total or “bad” cholesterol). For those above 50, it
is probably over 50%. The current medical advice is to keep your cholesterol
(especially the “bad” LDL-cholesterol, LDL-C) within normal range to avoid
heart disease. For those with high risk (eg. diabetics) or already have heart
disease, the medical management is to keep the total and LDL-C as low as
possible.
The
debate begins with whether high cholesterol is really an important risk factor
for heart disease? The second question is whether reducing cholesterol using statins reduces
the risk of heart disease? The third is whether using statins to reduce cholesterol reduces deaths from heart disease and deaths from all causes? Finally, overall, is the use of statins justifiable (benefits versus harm)?
Doctors
have been fed with results of studies that affirm the belief that cholesterol
is bad and reducing it improves the health outcome, and therefore convince them
that anti-cholesterol drugs are necessary. Now that regulations have come out
compelling drug companies to also release results of studies that are not in
favour of their drugs, we are beginning to see a more balanced picture.
THE CHOLESTEROL CONUNDRUM
About
two years ago, I wrote in Controlling
Cholesterol (Fit4Life 20/11/2011): “While there is no
doubt that many studies have shown the benefits of normalizing lipid levels (to
reduce the risk of heart attacks, stroke and peripheral arterial disease), my
concern is that most patients are put on the statin drugs without recourse to basic
and safer alternatives first.”
Since then I have
reviewed many reports and discussions on the subject and found that there are
many doubts on the supposed benefits of lowering cholesterol levels, in
particular the use of statin drugs to achieve that.
Some cardiologists
and cardiac surgeons (eg. Dr Stephen Sinatra, author of The Cholesterol Myth) also query the fact that many patients with
not-so-high cholesterol levels end up with serious blockage of their arteries,
while others with high levels do not have serious disease. While we all know
that heart disease has many contributing risk factors, so much focus has been
on cholesterol and the use of statin drugs to lower it. That is why so many
people are now on statins.
Most doctors now prescribe
statins to their patients because of the convincing “evidence” presented to
them over the last three decades. The standard model is that HDL-C is good for
the heart, and LDL-C is bad. So when we say high cholesterol is bad, we mean
high LDL-C, or high total cholesterol (Total-C) with a disproportionately high
LDL-C component. The risk value of the different cholesterol types is expressed
in the ratio Total-C/HDL-C. A value of 5 or more is considered high risk, and 4
or below is desirable.
According to WHO,
a third of ischaemic heart disease is attributable to high cholesterol, and
that a 10% reduction in serum cholesterol in men aged 40 reduces heart disease
by 50% in 5 years.
So some doctors
are so convinced of the benefits of statins that they prescribe them to almost
all their adult patients. One such doctor is Dr Michael Miller, the director of
the Center for Preventive Cardiology at the University of Maryland Medical
Center. He tells his patients to regard statins like a daily vitamin boost
because “it’s the only one that we know that works so well to improve
cholesterol and lower cardiovascular risk” (reported in WedMD).
His view is echoed
by Dr Patrick McBride, the director of the Cholesterol Clinic at the University
of Wisconsin School of Medicine and Public Health. He said that “Statins are
one of the great success stories of modern medicine” (reported in WebMD).
With such top
experts endorsing the use of statins, how can it be wrong? Well, nobody
disputes the fact that statins are very good at reducing cholesterol levels
(never mind the side-effects). What is contentious is whether high cholesterol
is really that bad; and whether reducing cholesterol levels lowers the
cardiovascular risks and overall health outcomes as claimed.
Many doctors and
researchers are now beginning to have a re-look at the role of cholesterol in
cardiovascular disease, the necessity of reducing cholesterol levels, and the
role of statins as the preferred treatment (in addition to diet and lifestyle
modification) to lower cholesterol significantly because the “evidence” has now
become shaky. Below are some examples of the contrary evidence (with
references).
CHOLESTEROL LEVELS MAY NOT CORRELATE WITH HIGHER OVERALL
DEATH RATES
A study across 5 European countries reported
in 2005 (European Jnl Epidemiology 2005,
Volume 20, Issue 7, pp 597-604) showed a strong correlation between cholesterol
levels and deaths from heart disease, but no correlation between cholesterol and
stroke or overall deaths (ie. from all causes).
If
the deaths from heart disease increase with higher cholesterol, but deaths from
all causes do not, that means deaths from other causes decrease with higher cholesterol. What is most important is
avoiding early death from all causes, not just from heart disease, as we have
all this while been focused to.
The
results imply that the higher cholesterol may be protective against other causes of death (eg. we now know that
higher cholesterol means lower deaths from haemorrhagic stroke, but higher
deaths from occlusive stroke such that overall there is no correlation between
cholesterol levels and stroke deaths). The other top cause of death is cancer.
Indeed some studies show that high cholesterol protects against cancer deaths.
However, for studies which include men and women, a different conclusion may be
arrived at if the data for men and women were studied separately (see Norwegian
study below).
Another study across 15 countries (14 countries in Europe plus Australian Aboriginals) shows no correlation at all between cholesterol levels and heart disease. Lithuania, with average cholesterol level of about 6 (mmol/L) has the highest prevalence of heart disease, while Switzerland, with the highest average cholesterol of nearly 6.5 has the third lowest heart disease prevalence. France has the lowest heart disease rate, while the average cholesterol level was about 5.7 (the French paradox comes to mind). The most puzzling is when all this is compared with the Australian Aboriginals whose heart disease rate is almost double that of the Lithuanians. Their cholesterol level (4.9) is lower than that of all the Europeans! (European figures derived from WHO MONICA Project; Australian Aboriginal data is for same period of study, courtesy Dr Malcolm Kendrick, author of The Great Cholesterol Con).
Most other studies
only compare the cholesterol - heart disease risk within a certain population,
and when multiple populations were studied, the results were often lumped
together. This cross-border comparison forces us to review the “direct”
correlation previously taken for granted.
This shows not only that there are other factors contributing to heart disease, but also that some of these other factors are more important, such that they throw the cholesterol - heart disease connection into disarray.
LDL-C IS NOT A RELIABLE PREDICTOR OF HEART ATTACKS
Risks factors are
valuable if they are reliable predictors of future disease. LDL-C has long been
accepted as a risk factor for cardiovascular disease. So it would seem logical
that lowering LDL-C should lower the risk. However, evidence-based medicine
cannot be based just on expectations. Thus it comes as a surprise that although
doctors have asked their patients to lower their LDL-C, so far no study has
actually been done to prove that lowering LDL-C to the target level reduces
heart disease.
A study on 100 heart
attack victims had in fact shown that their LDL-C levels were the same as in
the control group, which means LDL-C is not a good predictor of heart attacks.
The better predictor was hsCRP (high-sensitivity C-reactive protein), which is
a marker for inflammation (see Datta S,
et al. Comparison between serum hsCRP and LDL cholesterol for search of a
better predictor for ischaemic heart disease. Ind J Clin Biochem Apr-June 2011
26(2):210-213). I will elaborate more on the overlapping roles of
inflammation and cholesterol in the etiology of heart disease in future
articles.
A Harvard-led
study had in fact shown that it is the triglycerides (TG, another type of fat
routinely measured in the lipid-profile blood test), and not LDL-C, which is
the worse promoter of heart disease. They measured the various ratios involving
cholesterol and triglyceride and found that the most predictive of coronary
artery disease is the TG/HDL-C ratio, and not the total-C/HDL-C ratio that is
currently being used. The TG/HDL-C ratio does not include LDL-C at all (whereas
it is included in the total-C/HDL-C ratio, since LDL-C is part of the total-C),
thus again implying that the role of LDL-C as a risk factor has been
exaggerated (see Circulation 1997;
96:2520-2525).
WOMEN BENEFIT FROM HIGHER CHOLESTEROL
The
Norwegian HUNT 2 Study (J Eval Clin Prac 2012 Feb) followed 52,087 Norwegians
aged 20-74 who were free of cardiovascular disease (CVD) at the start, for 10
years. The study assessed the relationship of total cholesterol with total
mortality, CVD mortality, and heart disease mortality. It concluded that the
cholesterol-risk profiles for men and women were totally different. Women in
fact benefited from having higher cholesterol levels! See the chart below:
Risk of death from all causes in women
is lower with higher Total-C (starting from about 4.6 mmol/L onwards), but
increases for men (starting from about 5.3 mmol/L onwards).
The
chart may also explain why when women and men are considered together, there is
no correlation between high cholesterol and deaths from all causes. The reason
is that when we separate the data of the men and women, we find that the risk
rises for men, but reduces for women, and the two combined will cancel out.
Yet
until now, millions of women continue to be prescribed statins as primary
prevention, against the available evidence, to reduce their cholesterol when in
fact studies showed lowering the cholesterol increases their risk. A Harvard
study also showed that men above 69 also do not benefit from lowering their
cholesterol (the studies will be reported in the next article). I hope our
health care authorities take note of this “evidence-based” conclusion.
SO IS HIGH CHOLESTEROL BAD OR NOT?
I
have presented evidences that go against the current teaching that high Total-C
and LDL-C are such important risk factors for heart disease and that lowering
them is imperative. This may confuse patients and doctors alike.
I
hope that what I have presented proves that the current teaching about
cholesterol and heart disease has not been totally truthful to evidence-based
medicine, and doctors should re-examine their position. Cholesterol is not as
bad as it has been made out to be. In fact studies show that high cholesterol
may protect against deaths from heart
disease and against other causes of deaths in women, and doctors should be more
cautious in prescribing statins to them with the evidence presented. The bigger
culprit in heart disease is inflammation (more about this in future articles).
For
now, the evidence shows that for men, high cholesterol correlates with higher
heart disease and deaths from heart disease. So, does that mean lowering
cholesterol using statins in those with high levels reverses the risk? The
answer is not that simple (see next article).
In
general, women need not worry about having high cholesterol because they
benefit from it. And if you are a woman on statins, you should talk to your
doctor about going off it. You may be an exceptional case.
I
welcome comments and rebuttals from doctors who prescribe statins to their
women patients.
In
the next article, I will address the issue of whether using statins to lower
cholesterol is justified by evidence-based medicine.
DR AMIR FARID ISAHAK
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