Saturday, March 30, 2013

Cholesterol: What's up with that?

Dungeon Masters Guild
I'm sure you have realized that it is difficult to get any straight answers about cholesterol. Is it bad for us? Is it good for us? Is there one kind or two? I will attempt to clear up the misconceptions and our right lies, hopefully without getting too technical for the average Joe too understand, about cholesterol.

Do we even need it?

The first question to ask is do we need it and if so why. The short answer is yes we need it for a lot of things. Down at the bottom after the heading "What's it used for" I will explain what our body does with the stuff, so just bear with me, or skip down there if you prefer.

Is it really bad/good for us?

This is where most of the false information comes in. I hear it all the time, "be careful, cholesterol causes heart disease," or, "doctors are trying to kill you with those evil drugs, cholesterol is good for you and you need more of it." To further complicate things you often hear about cholesterol like it is all the same and sometimes they talk about the LDL Cholesterol being bad and HDL Cholesterol being good.
Well which is it? Who's telling the truth?
The answer is they are all partially right and partially wrong. I know this alone isn't a very helpful answer so let me continue.

First of all there is only one kind of cholesterol and we do need it for a variety of things and it does not cause heart disease, at least by it's self, and there is a difference between HDL and LDL.
I know what your thinking, "you just contradicted yourself. You said there is one kind of cholesterol and HDL and LDL are different." Well there is a good reason for this, HDL and LDL are not cholesterol.

So what are HDL and LDL anyways?

They are actually a kind of special protein the liver produces to deal with cholesterol, they stand for High-Density Lipoprotein and Low-Density Lipoprotein respectively, and they are so closely associated with cholesterol that they are usually just called HDL cholesterol and LDL cholesterol, because you should never see the proteins without the cholesterol or visa-versa.
These kinds of proteins are used to help move fats, like cholesterol, through the blood stream. This is important because, like oil and water, cholesterol and blood don't mix.
Now I could get into the difference between ionic and van der Walls forces and how they relate to water-soluble and fat-soluble substances, but I will opt for far simpler illustrations.

The first will only make sense if you have done much cooking, especially in the South. Imagine you are making some good old fashioned biscuits and gravy. To make the delicious white gravy you first cook up some ground breakfast sausage and you will then want to mix the resulting grease with milk, but grease and milk do not mix. For this to work you need something special, flour. Mixing the flour with the hot grease and the milk and you will magically produce the delicious white substance that tastes so good drowning your biscuits in the morning. HDL and LDL are like the flour in this example, it stops the cholesterol from separating from the blood.

Another way of looking at it, you can imagine that your blood is a bunch of tiny robots with magnet hands and the cholesterol is a big box covered with Velcro. You may notice the difficulty the little robots would have moving the box where it needs to go in this situation, magnets don't grab Velcro very well at all. The HDL and LDL are how this is overcome. You can imagine them being like something that can be wrapped around the box with magnets on one side and Velcro on the other. Now they can lift the box and move it wherever they need to bring it.

The only problem is that LDL can cause plaque in the arteries, resulting in heart problems, I know you don't like the idea that the body is the cause of all the problems.

What's difference between HDL and LDL?

For the most part the only real difference between them is size. HDL is much smaller and more compact and LDL is much bigger.
As I understand it LDL can result in plaque in the arteries because when the artery wall tries to grab the cholesterol covered in LDL and pull it in to use for cell production, sometimes some of the LDL will get knocked off into the bloodstream. This is a problem, because the LDL will begin to latch onto random things, like dead cells or wast, or cause the blood to clot. It is this ball of stuff that is called plaque and can eventually get big enough to block the flow of blood. Which, as you can imagine, doesn't produce very good results.

What does cholesterol medications do then?

The way most work is to prevent the liver from producing LDL, forcing the liver to rely more on HDL instead. There are a few exceptions that work in other ways, but this is how the vast majority work and your doctor will know what would be best for your specific situation.

What's cholesterol used for?

Don't freak out about the pictures of the chemical structures that follow, you don't need to understand the chemistry or any of the technical details about it. There is a lot of information that you don't need to worry about, I will point out what you should be looking at.

First thing first, this is what cholesterol looks like:
As you can see it has been separated into three parts and they are as follows:
   red    - alcohol functional group
   green - steroid group (take note of what this part looks like)
   blue   - a hydrocarbon tail

The part that is important for you to be able to recognize is the green shaded part, the steroid group. If you look carefully there are a total of four rings in it, three six-sided and one five-sided. This part is very important for the body to build a number of things.

One of cholesterol's most important uses is in the membrane around every cell in the body, which basically controls what can and can't get inside and holds it all together. You will see the word cholesterol in the bottom left of the image and a sharp eye will see that cholesterol looks completely unchanged from how it started.
You will see that cholesterol makes up about 20% of the membrane. It is basically used here to give structure and strength since that four ring structure will not twist or bend.
This alone is pretty significant, cholesterol makes up a reasonable portion of the protective barrier surrounding every cell in your body, but that is only the tip of the iceberg.

I'm sure you have heard that when you spend time in the sun, your body makes vitamin d. Well believe it or not, cholesterol is part of that was well.
Vitamin D3

Rotating this image 90 degrees you will see it is almost exactly the same as cholesterol. The biggest difference being that the middle of the six sided ring has lost a side. You will have to take my word for it that this small change makes a huge difference in how it will react.

The last use will mention here is a fairly important one. Our bodies make hormones out of it. Do you remember what that four ring structure looks like? If you don't take a quick look back.

For the example I will display two hormones that everyone should be familiar with:

Estrogen

Testosterone

It should be fairly obvious why the structure I mentioned is important for producing these hormones. The steroid group should be pretty obvious. In both of these cases very little is changed, besides the hydrocarbon tail being replaced with another functional group, and in the case of estrogen double bonds being added.

Hopefully this helps you to understand what is going on with cholesterol and why it is important.

   -Matt Smith