LDL Cholesterol

Low Density Lipoproteins are vessels used by lipidic substances to travel within the aqueous blood stream. Fatty substances like Cholesterol and triglycerides cannot travel, let alone, mix with the blood within a person’s body because oil and water don’t mix.

But the body needs both cholesterol and triglyceride to survive. The body uses cholesterol to regenerate cell membranes, create new cells and produce steroid hormones. Triglyceride, on the other hand are fat cells used by eukaryotes to store energy. This means that both these lipidic compounds are essential for the human body’s survival.

Unfortunately, since these lipidic substances cannot move freely within the water dominated body, they require transports to move from one place within the body to another where they are needed the most. In these situations, the transports that they use are lipoproteins. But depending on their destination, the lipoprotein that carries them may vary.

Low Density Lipoproteins (LDL) carry cholesterol and triglycerides from the liver, where they are made, to the tissues around the body. These LDLs, just like every lipoprotein, is a substance that is composed of both proteins and lipids. The outer layer is made of proteins which allows it to move and mix with water in the blood stream while the inner layer is lipidic which makes it compatible with other fatty substances allowing cholesterol and triglyceride to be stored in the core.

Since it’s purpose is to deliver cholesterol to the tissues, and since we were led to believe that cholesterol is bad for the body because it causes atherosclerosis, it paved the way for a belief that the cholesterol carried by LDLs are hazardous. Thus, the term “bad cholesterol” was associated with LDL.

Recently, there are doctors and health specialists that are trying to correct this misconception. The truth is that LDL is not bad cholesterol, it’s not cholesterol at all. And as much as LDL is no cholesterol, the package carried by this type of lipoproteins are not bad cholesterol either. The fact is that all cholesterols are the same. Whether it is carried by HDL or by LDL, cholesterol is cholesterol. There is no bad cholesterol nor good cholesterol.

Now, you might be asking how atherosclerosis are formed and what creates them.

Atherosclerosis was believed to be the accumulation of fats and cholesterol along the arterial endothelium causing the hardening of the arteries and blockage of the blood vessels. But according to recent studies the hardening of the arteries isn’t caused by the collection of cholesterol sediments along the arteries but the accumulation of white blood cells trying to repair damaged cells.

Atherosclerosis apparently is caused not by the amount of cholesterol in the body but the oxidation of LDLs which carry cholesterol.

When LDLs enter the arteries, it is susceptible to oxidants being pumped by the heart. These oxidants will alter the LDL’s chemical make up, thus oxidizing it. These oxidized LDLs will become hazardous for human tissues. When they get in contact with other tissues, the endothelium in particular, it will cause an inflammation that will trigger the immune system. The immune system will send macrophages, a type of white blood cell, to repair the damages. It will absorb the oxidized LDL to process it but since it carries lipidic substances, the macrophage will not be able to repair the damage totally. With this, more macrophages will be called to the scene to help repair the damages until layers upon layers of macrophages will collect in that area of the artery blocking the blood vessel.

Based on this explanation, some specialists now believe that healthy LDLs are not the main cause of atherosclerosis at all. The danger only arises when these LDL molecules are exposed to free radicals and become oxidized.

With this, the recommendation of these specialists is that we should have a regular intake of antioxidants to prevent the damaging of any particles or molecules within our body that will cause any type of maladies, or diseases. Of course, to minimize the chances of having an LDL oxidized by free radicals, it would be wise to lower the count of LDLs in the body.

HDL Cholesterol

Apolipoproteins are types or proteins that bind to lipids and create a new substance called “lipoproteins”. This new substance is unique and interesting aside from being an important substance in the body. It’s outer shell is composed mostly of proteins which allows it to be hydrophilic, or water soluble while the inside is lipidic which is compatible with cholesterol and triglycerides.

Since cholesterol is hydrophobic, it cannot travel nor mix with the water based blood stream so it will require a transport to travel from one point in the body to another. The transport that will carry these cholesterol molecules around the body are the lipoproteins. These lipoproteins will absorb cholesterol molecules and store them within tits core as it travels around the blood stream.

There are five known kinds of lipoproteins and all of which have its own characteristics and functions. These lipoproteins are: the Chylomicrons, Very Low Density Lpoproteins (VLDL), Intermediate Density Lipoproteins (IDL), Low Density Lipoproteins (LDL) and the High Density Lipoproteins (HDL). Of the five lipoproteins, the HDL and the LDL are the most popular because of their functions in the body.

The LDL, which carries cholesterols and triglycerides from the liver to the tissues are usually referred to as the “bad cholesterol” while the HDL, which carries cholesterols from the tissues to the liver are referred to as “good cholesterols”.

Now how do these HDLs function?

HDLs, move within the blood stream. As it moves around the body, it collects unused cholesterol from tissues. It will absorb these lipidic substances and store them in its core as it travels around the body. When it starts its rounds, the HDL’s shape is usually flat, but as it picks up cholesterols along the way, this lipoprotein will grow and change in size making it spherical. It will continue to grow as it absorbs cholesterol from the tissues and other lipoproteins. Then the cholesterol that it is carrying will be brought back either to the liver for excretion or recycling or to steroidogenic organs such as the ovaries, testes and adrenals.

One hypothesis which also led to the belief that HDLs are good cholesterols is that HDLs are capable of picking up the lipidic substances from the atherosclerotic areas of the arteries and deliver them back to the liver for excretion.

Based on the process and the function of these HDL molecules, it is obvious and easy to understand why this type of lipoproteins is very important for the body. With HDLs, our body maintains its health by keeping the unused cholesterol moving and preventing them from being rancid. At the same time it has properties that allow it to protect the body from suffering serious heart related illnesses.