Cholesterol: Is it Really that Bad?

What is Cholesterol? The Basics

Cholesterol is a complex type of fat, which is a waxy material in consistency, which circulates around the body with many other nutrients. Surprisingly, I use the word nutrient to describe cholesterol, but cholesterol is essential for life.

Most people believe that cholesterol is simply ‘bad,’ but without it, our cells would die, as cholesterol is required as part of the cell membrane to operate properly. It has grown a bad reputation over the years, with many myths still circulating, both in the popular press and even in some health magazines too. But more recent science shows that cholesterol in our diet is far less important than previously understood.

Cholesterol brings into the body the main building block for hormones such as testosterone (male hormone), estradiol (female hormone) and even vitamin D. You don’t need to be a chemist to see the similarity of cholesterol to these other key biomolecules and how it can easily be turned into both of these with minor modification.

It also helps to make the very important digestive bile acids made in the liver, which are essential for effective digestion of both fats and oils from our diet.

So, cholesterol is needed to sustain life. It is found in various meats, cheese, and eggs, though we don’t need to consume cholesterol in our diet, as the body can make this internally via a complex set of thirty-seven biochemical reactions.

In fact, only about 20% of blood plasma cholesterol will come from our diet, with the rest being synthesised in our liver from fats, sugars, and protein. We make around a gram (1000 milligrams) of cholesterol each day and typically we have around 35 grams in our body in total, at any one time. As a comparison we digest only around 300 milligrams a day.

To put this into perspective, if you eat around 200 milligrams of cholesterol this will only raise your cholesterol level by around 4mg/dL, which is a small increase, considering optimal cholesterol levels are around 200mg/dL.

Also, the body is very clever, in that its endogenous synthesis (cholesterol synthesis within the body) slows down if we digest cholesterol in our food. This is one of the reasons why reducing dietary cholesterol makes little difference to total measured blood cholesterol.

Unfortunately, some people do have a genetic defect which can cause the body to have very high levels of cholesterol, which needs to be treated with medicines like statins or fibrates, which help address this disease. This is called hypercholesterolemia, which basically means high cholesterol in the blood.

People can also vary enormously in terms of whether they are ‘high absorbers or low absorbers’ of cholesterol. Likewise, they can be ‘fast synthesisers’ of cholesterol or ‘slow synthesisers.’ We are all so different when it comes to our biochemistry and how our nutrition affects us too.

Cholesterol is both ‘Good’ and ‘Bad’

Since blood is 92% water and cholesterol is waxy and insoluble, it needs some kind of carrier to solubilise or dissolve it and carry it around the blood system. So, the body cleverly packages the cholesterol into miniscule protein-covered particles called ‘lipoproteins.’ The scientific name for fat is ‘lipid,’ hence the name lipoprotein. These lipoproteins are spheres of cholesterol and another fat called triglyceride (or TRIG), encapsulated in more biochemicals called ‘phospholipids.’ Finally, each sphere or particle carries one large protein on its coat called ApoB.

Just to make things a little more complicated, cholesterol can be carried all over the body in a range of these lipoproteins, but there are a variety of these lipoproteins.

Most people will have heard of LDL and HDL as these have been dubbed the ‘bad’ and the ‘good’ cholesterol respectively and there is certainly some truth in these labels. High levels of LDL can cause fatty deposits or ‘plaques’ on the inside of our artery walls. This is called ‘atherosclerosis’. It is quite a slow build up initially, but can eventually become a dangerous deposit, especially once the cholesterol becomes oxidised and later calcified. Then is the time when potentially serious narrowing of the arteries can take place, possibly resulting in future heart attacks, strokes, or other cardiovascular health problems.

Having a high LDL is a risk factor, but as is usual with nutrition and medicine, it is never that simple, as those with low LDL can still suffer from serious atherosclerotic plaques, and also those with very high levels of LDL can sometimes escape with little plaque formation. See below.

The Lipid Panel Blood test and Cholesterol

Routine blood tests will typically tell the doctor six main numbers when you have such a test. These include:

Typical blood data is shown below which shows optimal, intermediate, and also high or unhealthy levels of these various cholesterol levels. Both types of units are also included as different labs use different ways of expressing the results.

This type of panel has been used over many years and there are various ways of calculating risk of cardiovascular events.

It’s not the Amount of Cholesterol, but the Number of Particles

The latest science is now telling us that this cardiovascular risk is far more complex to predict, and the above set of data is seen by some experts as a little crude and needs updating.

Though the LDL level in a person’s blood panel data is undoubtedly a risk factor for heart disease, it is by no means a direct predictor of cardiovascular problems by itself. The latest science has now shown that the most influential cause of dangerous plaque formation is the number of particles of LDL and also the size of these particles. For a given amount of cholesterol, then it is obvious that if particles are smaller, then there will also be far more of these atherogenic particles in the blood.

This cholesterol particle number can be analysed in a blood sample by measuring a protein which is bound to each particle called Apo B100, but this test is not typically supported by the NHS, except under exceptional circumstances. This is a great pity, as many cardiologists and scientists believe that this simple measurement is the very best predictor of atherosclerosis and potential cardiovascular events.

One surprising fact is that early fatty streaks can be seen in even in children in their coronary arteries.

The mechanism which most scientists agree on nowadays, is related to how these particles get trapped within the arterial wall (the intima). Typically, it is these smaller particles that can enter the wall and get trapped, whereas the larger cholesterol particles tend not to enter the intima. This causes injury to the intima triggering the start of atherosclerosis. The intima can also be injured due to turbulent flow, circulation of reactive free radicals which are oxidising molecules, high homocysteine levels in the blood (see blog on homocysteine) and also elevated blood sugar levels.

In turn the usually protective white blood cells, such as monocytes and T cells then enter the artery wall initiating an ‘inflammatory cascade’ which in turn can later become more fibrous and structured, as collagen and elastin starts to form a harder polymeric layer. This is when disease really takes hold and becomes a potentially dangerous plaque which can either cause a vessel blockage or break off as a thrombosis and cause damage further ‘downstream.’

Other forms of Cholesterol

Most ingested cholesterol is what chemists call an ‘ester’, hence its name chol-ester-ol. This just means that the molecule is joined up with another molecule called a fatty acid. This is the form of cholesterol that we ingest when we eat meat or eggs for example.

However, there are other cholesterol-like molecules called sterols that exist at high levels in plants. These are called phytosterols. When ingested, sterols can compete with cholesterol for absorption and therefore phytosterols are known to reduce cholesterol levels in the blood.

However, the presence of a sterol of any type (cholesterol and plant based phytosterol) in an arterial wall is, potentially a risk factor for atherosclerotic fatty streaks in the arteries. This is a controversial area, but there is certainly evidence that plant sterols too can be atherogenic (causing plaques) and some scientists even believe that such sterols can be worse than cholesterol itself.

Treatments for Atherosclerosis

We know the risk factors comprise activities like smoking, being sedentary, eating a healthy diet, being overweight and of course drinking excessively. Everyone can control these to some degree. However, on occasion medication will be is necessary to lower risk.

These medicines comprise of:

a/ Statins

There is a range of statins that are part of the statin armoury including atorvastatin (Lipitor), pravastatin (Lipostat), simvastatin (Zocor) and rosuvatatin (Crestor). Typically, these are daily tablets (10 to 80mg/day) that are taken for life, to control LDL cholesterol levels. They work by inhibiting the synthesis of cholesterol, in the liver.

Some people will witness some common side effects such as headaches, nausea and many users complain about fatigue and muscle aches, though muscle pain can be alleviated somewhat by adding Co-enzyme Q10 supplementation. In fact many doctors add this automatically to their patients’ prescription, whilst others for some reason do not. There are quite a few interactions with other medicines such as warfarin, gout medications and some antibiotics. Even food such as grapefruit juice can interact with statins.

Rarely statins can cause increased blood sugar (pre-diabetes), damage to muscle cells, damage to the liver and memory problems too, though these are rare events.

b/ Blood Pressure (BP) Reduction

BP is a key risk factor for cardiovascular problems and arterial plaque build-up too. Therefore, on occasion BP lowering medications can also play a role in reducing risk. A high blood pressure will be typically start around 140/90 mm, though this is dependent on age. The 140mm refers to what is called systolic pressure, which is the pressure caused by when the heart is squeezing blood from its chambers, whereas the lower number (diastolic pressure) is when the heart relaxes between beats and is therefore a lower pressure. The difference will also indicate the ‘elasticity’ of the blood vessels.

ACE Inhibitors. Common BP lowering medicines like these will include drugs such as ramipril or lisinopril. These work by allowing the blood vessels to relax and widen, thereby lowering overall pressure. These medicines work by inhibiting the production of a hormone called angiotensin 2. Like statins, these are simply daily tablets

Calcium Channel blockers are other types of medicines which have a relaxing effect on the blood vessels and work by inhibiting calcium from entering the cells of the heart and arteries. There is a wide array of such medicines available to the doctor depending on exactly what is required. These can also work hand in hand with statins.

Beta Blockers are another medicine that is sometimes used for lowering BP and works by slowing the heartbeat, thereby causing the pressure to drop as a result. However, these have been found to be less effective in preventing heart attacks/strokes than other meds and are now not a first choice to most doctors.

Water Tablets or Diuretics is another form of medication used to help control BP and work by increasing the amount of both salt and water that is excreted, thereby lowering the amount of fluid in the cardiovascular system. These then tend to lower blood pressure. Thiazides are a commonly used diuretic and are good alternatives if other medicines prove unsuitable.

There is a raft of other pharmaceuticals available to the doctor which this article does not have the time to elucidate upon, but this is a huge field of medicine and BP lowering is such a key health biomarker to watch carefully and control where necessary.

The Main Messages

1. Cholesterol is essential for life and most of it is made in the body ,with diet playing a small role in  blood cholesterol levels.
2. Cholesterol exists in the blood in particles of ‘lipoproteins’ of variable size and density. The low density particles (LDL or bad cholesterol) is highly atherogenic, whilst the good or HDL cholesterol is a healthy form of cholesterol to have in our blood.
3. It is not the level of LDL necessarily, but the number and size of its particles which is causive of atherosclerosis and heart disease, but typically this is not measured in a normal blood panel.
4. Risk factors for atherosclerosis and heart disease are lack of exercise, smoking, being overweight and unhealthy eating, but all of these can be controlled to some extent by our own behaviours.
5. A range of medicines are available to control cholesterol levels and blood pressure which can lower risk of both atherosclerosis and cardiovascular disease in general.

The above article is purely for interest and knowledge and should not be construed as medical advice, as this will come from your GP directly. Discuss any health issues with your own doctor.