# RKS: THE 'BAD' CHOLESTEROL - Is All LDL-Cholesterol Dangerous?
# RKS: THE 'BAD' CHOLESTEROL
IS ALL LDL-CHOLESTEROL DANGEROUS?
DO STATINS REALLY PROTECT AGAINST LDL
ACQUAINTING WITH CHOLESTEROL & LIPOPROTEINS
Dear Reader,
Cholesterol is a bug word for the layman. Nearly 40% of adults have high cholesterol, and this lipid form is responsible for 4.5% of total deaths in the world. The medical professional always is on the lookout for the concentrations in blood for its carrier, namely, LDL-C i.e. low density lipoprotein cholesterol levels since the same is a known harbinger of all diseases associated with blood vessel blockages like heart attacks and paralytic stroke.
But LDL is like a jail that has the cholesterol captured within it. Just like all prisoners are not harmful, including those violent, can never cause havoc in Society until they are released, the same is with the cholesterol till it remains entrapped within the LDL molecule.
It makes an interesting study to be aware of the fine differences even amongst the ravaging capabilities of different LDL-C molecules, and thereby build body’s capabilities to prevent the latter from becoming a rogue.
LIPIDS vs FATS
There is a confusion across the strata of society, irrespective whether one is literate in science and biology of not, regarding understanding the difference between the words lipids and fats which is by and large a blurred concept.
Here it is essential to understand that cholesterol is not the only lipid. Triglycerides, another lipid form, on the contrary, are a more prevalent type since these constitute 90% of all oils and fats (examples being butter, cheese, etc. amongst solid lipids) consumed in food.
Mark you, do not get carried away by the term that a particular cooking oil is ‘cholesterol-free’. This promotion is medically correct since ALL oils only contain triglycerides and hardly ever any cholesterol … but … but … triglycerides – just like cholesterol, are lipids! It is akin to ordering a paneer palak and the waiter proclaiming it to be chicken-free!!
LIPOPROTEINS
Blood is 90% water and cholesterol being an 'oily-like' substance cannot freely mix with it. Hence, cholesterol needs to be escorted to different cells and tissues via blood by a special carrier called lipoproteins. Medically, there are 4 types of lipoproteins circulating in our blood:
- Mainly triglyceride carriers
- Chylomicrons
- Very low density lipoproteins (VLDL)
- Mainly cholesterol carriers
- LDL
- High density lipoproteins (HDL)
Since cholesterol is the focus of the world, including scientists, researchers and laymen, what one needs to be familiar are the LDL and HDL subtypes of lipoproteins.
Fig: Relative sizes of LDL particle.
Contrary to visual deducing, the HDL is the smallest particle whilst LDL is actually slight bigger - >2-4 times.
It is by far now general knowledge that HDL-C is the ‘good’ (and protective) cholesterol whilst the ‘bad’ (and harmful) one is the LDL-C.
LDL-C vs HDL-C
- Mainly triglyceride carriers
- Chylomicrons
- Very low density lipoproteins (VLDL)
- Mainly cholesterol carriers
- LDL
- High density lipoproteins (HDL)
Contrary to visual deducing, the HDL is the smallest particle whilst LDL is actually slight bigger - >2-4 times.
It is by far now general knowledge that HDL-C is the ‘good’ (and protective) cholesterol whilst the ‘bad’ (and harmful) one is the LDL-C.
LDL-C vs HDL-C
LDL
Each LDL particle carries 3,000 - 6,000 fat molecules. Since only 40% of lipid is non-cholesterol, each LDL transports 1,800 - 3,600 cholesterol molecules i.e. 0.00002 - 0.000004 picograms of cholesterol. Since the acceptable limits of total cholesterol carried by LDL is pegged at less than 130 mg/dL of blood, it could be inferred that there are over 10,000 quadrillion such particles roaming all over our body in blood.
Each LDL particle carries 3,000 - 6,000 fat molecules. Since only 40% of lipid is non-cholesterol, each LDL transports 1,800 - 3,600 cholesterol molecules i.e. 0.00002 - 0.000004 picograms of cholesterol. Since the acceptable limits of total cholesterol carried by LDL is pegged at less than 130 mg/dL of blood, it could be inferred that there are over 10,000 quadrillion such particles roaming all over our body in blood.
HDL
Each HDL particle carries 70 - 75 cholesterol molecules, which is approximately 25 - 30% of the total body's cholesterol content. HDL scavenges the free cholesterol present in blood and gutters the same through the liver via bile. Another mechanism why HDL is 'good' is because it protects LDL from being damaged by free radicals; if the latter do attack LDL to convert it to its lethal oxidised form, the cholesterol from such particles is selectively removed by HDL so as to nullify the 'bad' LDL and thereby curb its potential for causing atherosclerosis.
Notable HEART UK experts opine that the protective effect of HDL-C appears to reach its maximum at roughly 54.14 mg/dL and levels higher than these may not provide any extra protection.
Each HDL particle carries 70 - 75 cholesterol molecules, which is approximately 25 - 30% of the total body's cholesterol content. HDL scavenges the free cholesterol present in blood and gutters the same through the liver via bile. Another mechanism why HDL is 'good' is because it protects LDL from being damaged by free radicals; if the latter do attack LDL to convert it to its lethal oxidised form, the cholesterol from such particles is selectively removed by HDL so as to nullify the 'bad' LDL and thereby curb its potential for causing atherosclerosis.
Notable HEART UK experts opine that the protective effect of HDL-C appears to reach its maximum at roughly 54.14 mg/dL and levels higher than these may not provide any extra protection.
LDL-C
The LDL-C has been designed to serve a beneficial purpose and various guidelines recommended a limit of cholesterol intake between 200 to 300 mg as part of diet each day. All non-vegetarian food items such as eggs, sea food, beef, meat and chicken contain much more cholesterol as compared to dairy products, and the least (maybe nil) being present in vegetarian meals.
In addition to dietary intake, normal adults typically synthesize about 1,000 mg cholesterol per day and the total content of cholesterol in our body is about 35 gms. The liver is the primary organ that synthesizes cholesterol and it manufactures about 20-25% of total daily cholesterol produced by the body. Cholesterol is also synthesized in smaller quantities by the adrenal glands, intestines, reproductive organs, etc.
The functions of cholesterol include:
- Participation in the synthesis of the walls of every cell of the body.
- The myelin covering insulating the nerves is made from cholesterol.
- Cholesterol is converted to bile.
- For vitamin D and sex hormones manufacturing, cholesterol is necessary.
- Skin requires cholesterol for its structure.
Hence, LDL-C per se is not to be considered as our enemy. The issue is the excess of LDL-C in our body.
Table: LDL-C levels in blood and implications.
Is it only the levels of LDL-C that determine its enmity to the arteries? There needs to be an understanding more deeper than this so that one is not fooled by only the quantification of LDL-C and feel a safety net or otherwise.
The LDL-C has been designed to serve a beneficial purpose and various guidelines recommended a limit of cholesterol intake between 200 to 300 mg as part of diet each day. All non-vegetarian food items such as eggs, sea food, beef, meat and chicken contain much more cholesterol as compared to dairy products, and the least (maybe nil) being present in vegetarian meals.
In addition to dietary intake, normal adults typically synthesize about 1,000 mg cholesterol per day and the total content of cholesterol in our body is about 35 gms. The liver is the primary organ that synthesizes cholesterol and it manufactures about 20-25% of total daily cholesterol produced by the body. Cholesterol is also synthesized in smaller quantities by the adrenal glands, intestines, reproductive organs, etc.
The functions of cholesterol include:
- Participation in the synthesis of the walls of every cell of the body.
- The myelin covering insulating the nerves is made from cholesterol.
- Cholesterol is converted to bile.
- For vitamin D and sex hormones manufacturing, cholesterol is necessary.
- Skin requires cholesterol for its structure.
Hence, LDL-C per se is not to be considered as our enemy. The issue is the excess of LDL-C in our body.
Table: LDL-C levels in blood and implications.
Is it only the levels of LDL-C that determine its enmity to the arteries? There needs to be an understanding more deeper than this so that one is not fooled by only the quantification of LDL-C and feel a safety net or otherwise.
OXIDISED LDL
When oxygen free radicals attack and damage the lipids inside the LDL it is then referred to as oxidized LDL. It is the oxidized LDL particle that is most exclusively a known precipitator of atherosclerosis, and therefore a potential risk factor of various diseases affected by arterial narrowing such as cardiovascular as well as stroke.
Why is oxidised LDL a more lethal particle needs to be unveiled. After giving up the cholesterol to various parts of the body, where it is required for a specific function, the balance is transported back into the liver where there is a receptor [LDL receptor (LDLR)] which usually combines with the LDL-C. The latter is then taken inside the liver cell, after entering the receptor, and the cholesterol carried by LDL is removed and converted to bile. The LDL particle per se is then destroyed by the liver cell thereafter.
In the case of oxidised LDL, the LDLR cannot recognize it and the LDL-C levels not only remain high but also its cholesterol leaks out in blood to enter the walls of arteries and thereby cause its narrowing – atherosclerosis.
Acting as a transporter of such injurious cholesterol molecules, the oxidised LDL is the one that is dangerous amongst all the LDL-C roaming freely in blood. Hence, the mere levels of LDL-C that is usually estimated should not be the sole guidance; higher levels are should not be the sole concern provided the oxidation of the LDL particle has been prevented.
SMALL DENSE LDL
Most LDL particles are very close in size to the normal gaps in the wall of the arteries i.e. 26 nm. However variations occur in their dimensions and hence LDL can be grouped based on its size:
- PATTERN 'A': Large low density buoyant LDL particles
- PATTERN 'B': Small high density LDL particles
It is the small high density LDL particle that has been associated by some with a higher risk of cholesterol-initiating diseases. This is thought to be because the smaller particles are more easily able to penetrate the walls of arteries.
According to one study, sizes 22.0-25.5 nm were designated as pattern B and LDL sizes 26.0-28.5 nm were designated as pattern A. Thus the small high density LDL particle of <26 nm being able to easily penetrate the average 26.0 nm gaps in arteries is the very reason why the Pattern B type is the one that is dangerous to arterial health.
CONCLUSIONS
For those with known atherosclerosis diseases, the various guideline recommendations for LDL levels are to maintain less than 70 mg/dL but it is never specified how much lower is enough. Interestingly, it has been noted in children that before the development of fatty streak – the name given when cholesterol from a rogue LDL just seeps into within the arterial walls, the LDL-C levels have been noted to be 35 mg/dL. Maybe these are the safest for saving the arteries from any damage whatsoever.
However, besides the levels, the oxidised LDL-C and also the presence of small dense particles of LDL are more prognostic of a disease. There is a test to detect oxidised LDL in a laboratory and can be performed just like any other blood tests. For detecting small high density component of LDL-C separately there are also available enzyme-linked immunoassay (ELISA) tests.
However, prevention is better than detection should be the motto. To prevent oxidization of LDL antioxidants which are especially lipid soluble, and in the right amounts need to be taken on a daily basis. The best amongst these is coenzyme Q10 since till its last droplet persists in the LDL particle the free oxygen radicals cannot damage the latter. As far as minimizing the proportion of small dense LDL is concerned, the findings have been lower the triglyceride levels lesser is the Pattern B LDL proportion and vice versa. Hence, for lowering the small dense LDL particle numbers, keeping the triglyceride concentrations within normal limits could be the key.
The triglycerides that we consume are either saturated fatty acids, omega (n)-6 fatty acids or n-3 fatty acids in our daily diet. These 3 varieties of fatty acids play an interesting differential role in modifying the LDL particle.
Remember cholesterol in LDL is bad contrary to many roaming myths that cholesterol levels do not matter. Heart attacks and stroke occur because of narrowing of arteries and only cholesterol can do this and no other substance has been thus implicated. But it is a medical evident fact that LDL-C is actually ‘bad’ only when the particle is oxidised or the LDL is small and dense. It gets even more complicated than this - small dense LDL is more susceptible to oxidation! Thus, only statins to lower cholesterol is a half-baked effort to protect one’s arteries, it needs to be complimented with antioxidants and keeping a check on triglyceride concentrations. N-3 fatty acid supplements can serve as a double barrel gun by lowering triglycerides and changing small dense LDL into more buoyant large particles.
Have a safer cholesterol. Supplement statins with CoQ10 and n-3 fatty acids.
Or else, Pray for the arteries.
DR R K SANGHAVI
Prophesied Enabler
Experience & Expertise: Clinician & Healthcare Industry Adviser
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Very well explained concepts of LDL /HDL/Cholesterol particularly emphasis on oxidised LDL with importance of antioxidants alongwith Statins š
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