The Homo sapiens is, like the rest of the living beings, little more than a set of organic molecules ordered in space and time.
Of all of them, if there is one that stands out for its bad press and its stigma of perdition, that is cholesterol. It is the proscribed biomolecule, the plagued one, the pariah of organic chemistry. Everyone has heard of her but nobody wants her as the protagonist in their body.
But what do we really know about her?
Well, the first thing -and, if you rush me, the most important thing- is that without cholesterol we would be dead.
Cholesterol and its importance for life
The Cholesterol plays a decisive role in the performance of vital functions in the body. Here are some convincing examples:
1. It is a fundamental component of the cell membranes of animals (plant cells have molecules with a similar function called sitosterol and stigmasterol). It acts by regulating the fluidity of these membranes like a nightclub doorman; that is, controlling the “you do enter” and the “you don’t” to the “party” that is mounted in the cell cytoplasm.
two. It is the molecule from which sex hormones are synthesized. Its estimated estrogens and/or its valued testosterone are nothing more than derivatives of this steroidal lipid formed from cyclopentanoperhydrophenanthrene, sterane for friends.
Without cholesterol we would be nothing more than asexual beings in what refers to secondary sexual characteristics.
3. Cholesterol is also a precursor to cortisol (a hormone involved in raising blood glucose) and aldosterone (a hormone that raises blood pressure). Speaking clearly: without them we would have a very reduced ability to react quickly in a situation of danger or biological stress.
4. Cholesterol is basic in calcium metabolism as it is the precursor of vitamin D (that is why this vitamin is called cholecalciferol). Without cholesterol we would have a clearly inefficient skeleton and with osteoporosis that would fracture our bones at the slightest pressure.
5. Cholesterol is also the biochemical substrate for the formation of bile salts, substances that our gallbladder secretes and allow us to emulsify the fats we eat.
6. In specific areas of the membranes (especially neuronal membranes), and according to recent studies, cholesterol (associated with glycolipids and sphingolipids) would form highly impermeable molecular microdomains and are involved in the rejection of pathogens such as bacteria or viruses.
So, where is the problem?
After the above, it is not explained by why our doctor is so interested in lowering cholesterol. Let’s try to clarify it.
The way the body has to move substances through our body is through the blood. But blood is an aqueous liquid and cholesterol is a hydrophobic molecule totally insoluble in water media. In order to mobilize it, our physiology resorts to an invention similar to chocolates: lipoproteins.
We are talking about macromolecules whose filling would be the hydrophobic part (cholesterol and triglycerides, fundamentally). The chocolate coating would be formed by proteins and phospholipids with the hydrophilic part facing outwards, which allows the bonbon to travel through the circulatory system and cholesterol, specifically, to travel on this train.
Well, certain types of lipoproteins, when they get too high, run a serious risk of becoming embedded in the walls of our arteries, producing the dreaded atherosclerotic plaques.
Said in silver, crashed cholesterol trains clog our pipes.
But not all lipoproteins imply the same level of atherogenic risk. For this reason, and given that we can divide our total cholesterol according to the lipoprotein in which they travel, the fame enjoyed by the different cholesterols is very different.
The good, the bad and the ugly
There are five types of lipoproteins in our blood: chylomicrons, very low density lipoproteins ( VLDL), low-density (LDL), intermediate-density (IDL) and high-density (HDL).
Of these, only three would be directly involved in the transport of cholesterol and one of these, when raised, is the one that runs the serious risk of putting our biological pipes in check.
These three lipoproteins generate the well-known three fractions of cholesterol:
The good
High density lipoproteins (high density lipoproteins or simply HDL) are those that transport cholesterol to the liver. There a part will be used for the synthesis of hormones and what is left is eliminated through the bile towards the digestive tube. From there, to the outside through the feces.
As the role of HDL is to remove cholesterol from peripheral tissues (including those deposited in the walls of the arteries) to the liver, The fraction of cholesterol that travels in the blood on this train (HDL-cholesterol) is called good cholesterol.
Bad cholesterol can cause narrowing of blood vessels. The bad
Low density lipoproteins (low density lipoproteins or LDL) are lipoproteins that release cholesterol from the liver into the bloodstream and are directly associated with the risk of coronary diseases.
This LDL-cholesterol would have four basic harmful effects on our ar Theries:
1. Reduces the lumen of the vessel, reducing blood flow in that area.
2. It creates irregularities on the surface of its walls, generating “turbulence” in the blood flow and feeding back the formation of new irregularities.
3. If the plaques grow they can completely clog the pipe, causing stenosis (narrowing) of the vessel and even infarcting the irrigated tissue (due to lack of oxygen). If this happens to us on the tip of the little toe, we may not even know about it. But if it occurs in the coronary arteries (those that supply the heart) it will cause an unwanted myocardial infarction.
4. All or part of the plaque obstructing the vessel can be detached from the wall. In that case, let’s not celebrate the unstuck. The plug (thrombus) will travel through the bloodstream and become stuck where you least expect it with highly variable consequences. At the end of the earlobe it will not take away our sleep, but if it does in a cerebral artery, it will suffer a stroke that will take away something much more serious (if not life).
The ugly
Very low density lipoproteins (very low density lipoproteins or VLDL), like LDL, are lipoproteins that release cholesterol from the liver into the bloodstream. However, VLDL-cholesterol (with this ugly and complicated name) is considered a less relevant cholesterol assessment factor than LDL-cholesterol for two reasons.
First because it transports triglycerides in a much higher proportion than cholesterol. Second, because its analytical determination is very complex and the laboratory resorts to indirect methods that are not representative when triglycerides are very high in the blood. In these cases, the value of VLDL-cholesterol confuses rather than clarifies.
Advantages and disadvantages of this classification
This is a convenient classification that is easily understood by a wide audience, which is a great advantage. In addition, it is useful as long as the values of the cholesterol fractions are not considered only in absolute value but are weighed by estimating the importance of the HDL/LDL and total cholesterol/HDL cholesterol ratios (atherogenicity or Castelli index).
But it also has drawbacks. We are many analysts who think that this classification can lead to erroneous generalizations. In fact, having an elevated HDL fraction does not always guarantee an “atheroprotective effect”.
Furthermore, the functions of lipoproteins are much more complex than the simple transport of molecules, which leads to the mistake of believing that some are beneficial for health (HDL) and others are not (LDL).
Conclusion: the ugly it’s not the VLDL-cholesterol, rather the ugly one is the classification.
*This article was originally published on The Conversation. You can read the original version here.
A. Victoria de Andrés Fernández is a full professor at the Department of Animal Biology at the University of Malaga.
You may be interested in:
Do you suffer from high cholesterol? It could be because of your genetics
How to lower cholesterol: These 5 changes will can help
7 mistakes in the diet to lower cholesterol
124239853
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There are five types of lipoproteins in our blood: chylomicrons, very low density lipoproteins ( VLDL), low-density (LDL), intermediate-density (IDL) and high-density (HDL).
Of these, only three would be directly involved in the transport of cholesterol and one of these, when raised, is the one that runs the serious risk of putting our biological pipes in check.
These three lipoproteins generate the well-known three fractions of cholesterol:
The good
High density lipoproteins (high density lipoproteins or simply HDL) are those that transport cholesterol to the liver. There a part will be used for the synthesis of hormones and what is left is eliminated through the bile towards the digestive tube. From there, to the outside through the feces.
As the role of HDL is to remove cholesterol from peripheral tissues (including those deposited in the walls of the arteries) to the liver, The fraction of cholesterol that travels in the blood on this train (HDL-cholesterol) is called good cholesterol.
The bad
Low density lipoproteins (low density lipoproteins or LDL) are lipoproteins that release cholesterol from the liver into the bloodstream and are directly associated with the risk of coronary diseases.
This LDL-cholesterol would have four basic harmful effects on our ar Theries:
1. Reduces the lumen of the vessel, reducing blood flow in that area.
2. It creates irregularities on the surface of its walls, generating “turbulence” in the blood flow and feeding back the formation of new irregularities.
3. If the plaques grow they can completely clog the pipe, causing stenosis (narrowing) of the vessel and even infarcting the irrigated tissue (due to lack of oxygen). If this happens to us on the tip of the little toe, we may not even know about it. But if it occurs in the coronary arteries (those that supply the heart) it will cause an unwanted myocardial infarction.
4. All or part of the plaque obstructing the vessel can be detached from the wall. In that case, let’s not celebrate the unstuck. The plug (thrombus) will travel through the bloodstream and become stuck where you least expect it with highly variable consequences. At the end of the earlobe it will not take away our sleep, but if it does in a cerebral artery, it will suffer a stroke that will take away something much more serious (if not life).
The ugly
Very low density lipoproteins (very low density lipoproteins or VLDL), like LDL, are lipoproteins that release cholesterol from the liver into the bloodstream. However, VLDL-cholesterol (with this ugly and complicated name) is considered a less relevant cholesterol assessment factor than LDL-cholesterol for two reasons.
First because it transports triglycerides in a much higher proportion than cholesterol. Second, because its analytical determination is very complex and the laboratory resorts to indirect methods that are not representative when triglycerides are very high in the blood. In these cases, the value of VLDL-cholesterol confuses rather than clarifies.
Advantages and disadvantages of this classification
This is a convenient classification that is easily understood by a wide audience, which is a great advantage. In addition, it is useful as long as the values of the cholesterol fractions are not considered only in absolute value but are weighed by estimating the importance of the HDL/LDL and total cholesterol/HDL cholesterol ratios (atherogenicity or Castelli index).
But it also has drawbacks. We are many analysts who think that this classification can lead to erroneous generalizations. In fact, having an elevated HDL fraction does not always guarantee an “atheroprotective effect”.
Furthermore, the functions of lipoproteins are much more complex than the simple transport of molecules, which leads to the mistake of believing that some are beneficial for health (HDL) and others are not (LDL).
Conclusion: the ugly it’s not the VLDL-cholesterol, rather the ugly one is the classification.
*This article was originally published on The Conversation. You can read the original version here.
A. Victoria de Andrés Fernández is a full professor at the Department of Animal Biology at the University of Malaga.
You may be interested in:
Do you suffer from high cholesterol? It could be because of your genetics
How to lower cholesterol: These 5 changes will can help
7 mistakes in the diet to lower cholesterol
124239853
Now you can receive notifications from BBC Mundo. Download the new version of our app and activate them so you don’t miss our best content.
Do you already know our YouTube channel? Subscribe!