The Cholesterol Myth
As a pharmacist, I have lost count over the years of the number of conversations I have had with people who are concerned about their “high cholesterol” which increases their heart disease risk.
Cholesterol has had a bad name since the very flawed “Diet Heart hypothesis”.
For about 60 years, we have been taught that what we eat, especially the fat in your diet, affects the fats (cholesterol) in your blood, which causes heart disease. Therefore, if we eat a low-fat diet, this will lower blood fat/cholesterol and decrease the risk of heart disease. There are now industries set up around this theory – especially low fat foods and medications (statins) to lower your cholesterol levels.
However, one important point has been missed…does lowering cholesterol levels actually translate to lower rates of heart disease and people being admitted to hospital with conditions like heart attacks?
Actually in many cases no.
Cholesterol is actually very important for your health, especially brain health.
Let’s take a closer look at cholesterol.
Cholesterol is an important substance in the body. It is found in the wall of every cell and keeps the cell wall firm but flexible, allows the correct molecules to pass through, and helps the cell function properly. These functions can range from keeping your blood thin (but not too thin), allowing glucose to enter cells, to burning fat, to making muscle… and more.
About 20-25% of the body’s cholesterol is found in the brain, where it is vital for allowing good communication between nerves. This is a lot considering that the brain only makes up about 2% of the body’s weight.
Cholesterol is vital for good brain function. Good brain function relies on good connections between all the nerves in the brain. These connections, called synapses rely on cholesterol. A lack of brain cholesterol is linked to memory loss and cognitive impairment. It may also be linked to the development of dementias such as Alzheimer’s disease.
But wait – there’s more!
Cholesterol is the base chemical for all of our steroid hormones, such as oestrogen, testosterone, or cortisol. So good reproductive health (and baby’s health) revolves around good cholesterol. Vitamin D is made in the skin from cholesterol after exposure to UV (sun)light. A lack of vitamin D is linked to type 2 diabetes, heart disease, certain cancers, Alzheimer’s disease and osteoporosis and increased risk of bone fractures.
We also need cholesterol to make bile acids. Bile acids are needed to digest fats; which are critical for good health!
Overall, cholesterol is a vital component of health and wellbeing.
So why are we concerned about high cholesterol levels?
For years, we have believed that people with high blood cholesterol levels have an increased risk of cardiovascular disease, and there is some evidence to support that theory. But, as with most things, it is far more complicated than that.
About 75% of the body’s cholesterol is made in the liver. The rest comes from food. All the cholesterol in food goes through the liver before being transported to the rest of the body. Cholesterol cannot travel in the blood stream easily by itself. It has to be transported in special carriers called lipoproteins. Simply stated, low-density lipoproteins (LDL) carry cholesterol away from the liver, and high-density lipoproteins (HDL) carry cholesterol back to the liver for reprocessing.
It is these lipoproteins (not the cholesterol they carry) that have a stronger association with cardiovascular disease, with high levels of LDL and low levels of HDL linked to heart disease. But again – there’s more! Lipoproteins do not just carry cholesterol. They also carry triglycerides. Triglycerides are what all extra calories digested by the body, that are not needed or processed immediately, are converted into. These are transported by the lipoproteins to be stored in fat cells, and can be used later for energy. High levels of triglycerides have a much bigger impact on cardiovascular disease risk, than “cholesterol”, especially LDL-cholesterol.
Given that about half of the people who present to hospital with a cardiovascular “event” such as severe angina have normal cholesterol levels, this should tell us that there is more to heart disease risk than just cholesterol levels.
It feels a bit like that old nursery rhyme about the little old lady who swallowed a cow to catch the goat, to catch the dog, cat, bird and spider… to catch the fly she accidentally swallowed.
Perhaps she’ll die… but perhaps not. It’s the same here, we thought the issue with heart disease was total cholesterol, then the lipoprotein carriers, and currently it’s triglyceride levels, or maybe the size of your LDL particles… or both.
So if not cholesterol, then what?
Actually in the big picture, as a pharmacist, I am not overly concerned about your cholesterol levels.
What I really care about is your overall risk of having a heart attack or other cardiovascular event. Your cholesterol levels make up part of the risk picture.
But cholesterol levels actually have a small impact on your overall risk. Your age, sex, ethnicity, family history, smoking history, and blood glucose levels have a much bigger overall impact on your disease risk.
Lifestyle changes to lower heart disease risk.
If you want to lower your overall risk of cardiovascular disease there is lots you can do:
|1||If you are smoking, stop||This will have more of a positive impact on your cardiovascular health than anything else I can suggest.|
|2||Look at your diet||
There is no evidence to support low-fat diets, lowering saturated fats, or low-sodium diets for improving heart health.
The best of the current evidence suggests that we can lower our risk of cardiovascular disease if we can lower our triglyceride levels. The good news is, most of the recommendations for lowering triglyceride levels will also lower glucose levels – which will also benefit heart health.
|3||Get more activity|
|4||Get good quality sleep|
|5||Spend time outside each day in the sun (don’t get burnt)|
Click here to read the next article in the series on Statins: do they serve any purpose?