Monday, 24 June 2019

Cholesterol’s not necessarily bad... as long as there’s not too much

LIKE the internet, clean running water and the convenience of light at the flick of a switch, there are many things we take for granted in this day and age without necessarily knowing too much about how they work.

Cholesterol seems to be the medical equivalent of this; we know that too much of it is a bad thing, but what is it, what does it do and why is too much of it bad?

Let’s start with what it is. Cholesterol, from the Greek “chole”, meaning bile, and “stereos”, meaning solid, is an organic molecule that falls under the umbrella of what we call lipids.

Lipids are molecules made up of different combinations of carbon, hydrogen and oxygen atoms. When solid they are known as fats and when liquid they are known as oils.

Cholesterol (a waxy solid at room temperature) is one of many different fats that circulate and function within our bodies. It is worth mentioning that cholesterol, like lipids in general, is not inherently bad. Indeed, it is of vital importance to us. It is an integral part in the structure of our cell membranes (plants, for example, do not produce much cholesterol so have to go to the trouble of producing a cell wall in addition to a membrane to provide structure and containment).

Cholesterol also helps in certain intracellular signalling processes, helps absorb certain other fats from the intestines along with various soluble vitamins and is a precursor to certain vitamins, steroid hormones and sex hormones. It’s one of those jacks of all trades.

All cells in our body synthesise and produce all the cholesterol we need — even before we ingest it in our diet — but the vast majority is produced in the liver.

Much of it is then pushed through to the gall bladder, where it joins up with all our bile acids and from there goes into the intestines to help with absorption of vitamins and fats. It is transported in the blood, which is where we are able to measure its levels.

Because cholesterol is a solid and not water soluble, it needs to piggyback on to proteins in the form of substances called lipoproteins in order to get around our circulatory system.

During the Fifties, scientists classified various types of lipoproteins according to the density of protein compared to lipids. Thus the terms LDL (low density lipoprotein) and HDL (high density lipoprotein) were born.

Through various studies of levels of these lipoproteins in patients with and without cardiovascular issues, it was found that higher levels of LDL were less favourable than higher levels of HDL.

You may have heard people talk about “good” and “bad” cholesterol. Actually, the cholesterol is exactly the same in both — the good and bad aspects come from whether it is packaged into either HDL or LDL.

This is where we start seeing the drawbacks. In the modern era, we eat far more dietary fat.

High saturated and trans-fats in our diets are contributing to ever higher levels of cholesterol in our bodies on top of that which we produce from within.

The problem with this is the accumulation of cholesterol, specifically as LDL, in our blood. The process is quite complicated but, broadly speaking, this particular type gradually builds up plaques on the walls of the vessels — a process known as atherosclerosis that has the potential to block the flow of blood.

If this happens in one of the coronary arteries, it will cause a heart attack. If it happens in your brain or neck, it may cause a stroke. Things like peripheral vascular disease and angina result from partial blockages.

To put it crudely, LDL is the physiological equivalent of the non-flushable wipes that contribute to the fatbergs in sewers that we hear about.

There can often be a genetic element to this. If high cholesterol runs in the family, it may be that there are fewer receptors on cells that help offload cholesterol from LDL, thereby creating a back-log.

This is why it is worth having your cholesterol checked every now and again. If you have a significant family history of very high cholesterol, even if you are young (I’m talking even as young as twenties), it is worth getting a check to ensure everything is all right.

If you are overweight, have a poor diet or have any of the following signs of high cholesterol, the same applies.

Some people with high readings have signs of high cholesterol on their skin through small deposits over tendons or around the eyes. These are called xanthoma or xanthelasma and it has even been suggested that such signs were present on the Mona Lisa who is believed to have died quite young.

Even if your total cholesterol is low, a high LDL and/or low HDL or a ratio of more than four between them suggests room for improvement.

Triglycerides are another form of fatty substance that, if raised, has the same risk factors for cardiovascular disease. Often if this is raised alongside everything else it can suggest a more familial element.

If you have had this all checked and it indicates your cholesterol is high, the best way to combat this is through lifestyle. Exercise, reducing fatty foods and avoiding smoking as always are vital. Smoking produces a chemical in the blood called acrolein which acts on HDL, preventing it from transporting cholesterol away from areas of atherosclerosis.

If you have too many risk factors for this alone to be adequate, for example high blood pressure, previous heart attack or continued smoking, then medication can be added.

In 1964 scientists identified the process behind the synthesis of cholesterol and won a Nobel prize for their efforts.

Essentially, this involved an enzyme called HMG-CoA reductase. The inhibition of this enzyme is the basis for statins, which help to reduce levels of cholesterol but also slow the progression of existing atheromas in the blood and therefore, even if your cholesterol is within normal levels, will have a benefit.

Other medications are available if statins don’t suit — the most common side effect is muscle aches but doses can often be adjusted and supplements added to help with these. The benefits of statins cannot be underestimated.

Most importantly, even if you have to take medication to help with your cholesterol, it is not an invitation to dust off the pastries. Avoid cakes, fatty cuts of meat, butter, ghee, lard, cream, cheese, chocolate, coconut oils and creams.

Try lower cholesterol spreads but watch out for the labels in case the lack of cholesterol has paved the way for some other nasty stuff like excessive salt or sugar.

For those aged between 40 and 74, the NHS health check is available at GP surgeries and part of this involves a check of your cholesterol level. It’s worth doing and, even if you don’t fit into that age category but are concerned about your cholesterol, you can always speak to your GP about this or check out the cholesterol page on NHS Choices for more information.

As with most things, cholesterol isn’t necessarily the bad guy — as long as there’s not too much of it.

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