If you’ve ever looked up
cholesterol on the internet or had a discussion with your doctor, you might
know that there is “good” and “bad” cholesterol in the body. You may have also
been told that having more good cholesterol can help reduce the amount of bad
cholesterol in the body.
This was regarded to be true – up
until current research. Recently, scientists
have started questioning the conventional view of good and bad cholesterol, claiming
that this belief might be part of the reason for the recent rise in coronary
heart diseases.
Before we dive into this discussion,
let us first understand what cholesterol is and what we mean when we say ‘good’
and ‘bad’ cholesterol.
What is Cholesterol?
The foods we eat contain fats in
the form of triglycerides. When we eat a meal rich in fats, such as dairy
products or meat, the fats are absorbed as triglycerides, and the number of
triglycerides in the blood remain high for a few days after eating the meal.
After some time, the liver packages these triglycerides and converts some of
them into cholesterol, a waxy fat-like substance that is stored in adipose
tissues.
Apart from this stored form,
cholesterol is present in all cells of the body. It is used as a building block
for making various hormones, some vitamins (D), and digestive juices that help
break down fats in the food we eat.
There’s no doubt that cholesterol
is imperative for many bodily functions, but when levels become too high, it
starts to deposit and accumulate in blood vessels. This narrows the diameter of
the vessels passage way and is a common cause of many vascular and
heart-related diseases, such as angina, stroke, and heart attacks.
The Concept of Good and Bad Cholesterol
Fats, also called lipids, attach to
proteins to move through the body. This combination of fats and proteins are
called ‘lipoproteins.’ The two main lipoproteins
responsible for the transport of cholesterol are high-density lipoprotein (HDL) and
low-density lipoprotein (LDL).
The total amount
of cholesterol in the body is determined by adding the number of HDL and LDL. This
amount, along with the number of triglycerides in the body, is used by
clinicians as an indicator for assessing the risk of cardiovascular disease,
coronary artery disease, and vascular disease.
High-density
lipoprotein, or HDL, is what doctors normally refer to as ‘good’ cholesterol. This
is because an association between high levels of HDL and a lower risk of heart
disease, vascular disease, and stroke has been established by many research
studies. Therefore, HDL is believed to have a protective role against damage to
blood vessels and various complications related to the heart.
On the other
hand, low-density lipoprotein, or LDL cholesterol, is what doctors call ‘bad’
cholesterol. Elevated LDL levels in the blood are regarded as the primary risk
factor for atherosclerosis, which are the fatty deposits that clog arteries.
Narrow arteries
make the movement of blood difficult, which makes the heart work harder to pump
blood efficiently around the body. This increases the risk of developing
angina, heart disease, artery disease, and even stroke.
Experts also
believe that HDL plays the part of a scavenger. HDL transports one-third to
one-fourth of LDL cholesterol in the blood away from arteries and back to the
liver, where it is broken down and removed from the body as waste.
So, generally speaking, you should have
higher levels of high-density lipoprotein (HDL) cholesterol and lower levels of
low-density lipoprotein (LDL) cholesterol.
But Are There
Really Good and Bad Cholesterols?
Now that we’ve understood what
cholesterol is and what LDL and HDL do, let’s talk about the recent debate on
their roles in heart health.
In 2017, cardiologist Dr. Robert Du Broff shared
some new findings in the journal Evidence-Based
Medicine. According to his research, a trial of the drug evacetrapib, given to
high-risk patients with coronary heart disease, reduced LDL cholesterol by 37%
but did not reduce patient mortality (death rate). He, therefore, stated that
this adds to the growing evidence that challenges the ‘cholesterol hypothesis’
and might have instead led to the drastic rise in coronary heart diseases.
Another study, consisting
of 135,000 adults and published in the journal Lancet, concluded that “high
carbohydrate intake was associated with a high risk of total deaths, where total
fat and individual types of fat intakes were related to lower total death rate.”
Studies
such as these have created major doubts in the theory of ‘good’ and ‘bad’
cholesterol and their roles in cardiovascular disease. Doctors are now shifting
the blame to carbohydrates instead. Carbohydrates, also known as saccharides,
are the sugars or starches found in grains, fruits, vegetables, and milk
products. Carbohydrates are the main source of energy for most organisms, but
also are a major source of inflammation in the body when consumed in excess.
According to UK-based
researcher, Dr. Zoe Harcombe, who has written extensively about the benefits of
cholesterol on health, it is an excess of carbohydrates, which leads to
inflammation, that poses the most risk to the heart. She argues that the body
would die instantly without cholesterol since it is vital for many important
functions such as hormone production, brain function, memory, and even
digestion. She further claims that the body itself makes cholesterol, and the brain
stores about 25% of it, further highlighting its importance to the body.
“There is no such thing
as good cholesterol and bad cholesterol. Cholesterol is cholesterol. The
chemical formula for cholesterol is C27H46O. There is no good version or bad version of this
formula” – Dr. Zoe
Harcombe.
Irish
Heart’s dietitian Sarah Noone says that referring to cholesterol as ‘good’
or ‘bad’ is scientific, but not for health reasons. She explains: LDL (bad) cholesterol
transports cholesterol from the liver to cells that need it, but an excessive
amount of LDL in the blood can accumulate in blood vessels. This is where the
‘good’ or HDL cholesterol comes in. HDL transports cholesterol from cells back
to the liver for breakdown and removal. It is for this reason that they’ve been
termed good and bad – LDL is bad since it can accumulate and cause harm to
arteries, and HDL is good because it keeps transporting excess amounts back to
the liver.
But how
can we be sure? After all, the theory of ‘good’ and ‘bad’ cholesterol has
existed for ages!
Dr. Neville Wilson, Medical Director of the
Leinster Clinic, might have the answer: “All cholesterol is good, and in
some cases, low concentrations of cholesterol may compromise health.”
First, Dr. Wilson corrects
that cholesterol is an alcohol and not fat; therefore, it cannot cause ‘fatty
plugs’ that block arteries. According to him, all lipoproteins in the body
serve important functions, even the bad LDL cholesterol. LDL plays an important
role in protecting against certain bacterial infections, especially among the
elderly, which is why Dr. Wilson says they shouldn’t be given
cholesterol-lowering drugs.
However, he also points
out that both LDL and HDL cholesterol can be damaged due to exposure to toxins
or unhealthy lifestyles that includes habits like smoking or high sugar
consumption. This can lead to arterial wall inflammation, plaque formation, and
ultimately cardiovascular disease. Obviously, cholesterol cannot be blamed as
the only factor here.
Citing a study similar to
the one conducted by cardiologist Dr. Robert Du Broff, Dr. Wilson
concludes that in their undamaged state, both LDL and HDL cholesterol perform
crucial physiological functions, and neither is good or bad.
Dr. Harcombe further
defends the concept that LDL cholesterol isn’t bad. “With damaged arteries, the
LDL-C taxi cabs transport lipids to the scene of the damage to repair it. They
didn’t cause the damage. Firefighters attend fires; they don’t cause them. LDLs
are firefighters.”
Being blunt, she states
that calling HDL ‘good cholesterol’ is ignorant. HDL is famously known as the
‘scavenger’; however, it simply picks up those lipids that were transported
from the liver by LDL and weren’t used. So we can’t give HDL the entire credit
for being ‘good.’
What’s Happening Now?
Highlighting a study conducted in 2009,
in which 75% of adults hospitalized for heart attacks had low levels of LDL
cholesterol, Dr. Harcombe cans the idea that LDL cholesterol is a risk factor
for cardiovascular disease. Similarly, a 2016 report in the journal BMJ
Open examined 19 studies involving 68,000 elderly individuals and
discovered that high LDL cholesterol was associated with a lower death rate,
concluding that the results were “inconsistent with the cholesterol
hypothesis.”
Dr. Wilson supports this
notion and says that high cholesterol isn’t a ‘cholesterol’ problem, but might
indicate a reversible problem somewhere else, such as a hormonal dysfunction,
high blood pressure, massive inflammation, or simply high HDL cholesterol in a
healthy individual.
Now that it’s no longer
conclusive that high levels of ‘bad’ cholesterol and low levels of ‘good’
cholesterol increase the risk of death from cardiovascular disease, researchers
are currently focusing on anti-inflammatory drugs rather than
cholesterol-lowering drugs in their quest to reduce cardiovascular-related
disease and death.
With evidence for the cholesterol hypothesis coming under fire
within the scientific community, and with the public continuously arguing over the
best dietary advice, there is at least one positive message we can all agree
upon – to help reduce the risk of cardiovascular disease and keep both our
carbohydrate and cholesterol levels in check, we must avoid processed and sugary
foods, smoking, alcohol, and add in more physical activity. After all, the key
to staying fit is a healthy and balanced lifestyle, no matter what ‘good’ or
‘bad’ things lie within.