In this lesson we will discuss cholesterol and learn what it does do our bodies, both positively and negatively. Read about the sources, uses, and dangers of cholesterol, and then test your knowledge with a short quiz.
Definition of Cholesterol
It’s that time of year again. You get to have your annual checkup, where the nice doctor in the white coat will listen to your heart, take your blood pressure, and look at a little vial of your blood. When those blood tests come back, he invariably has some confusing numbers he wants to talk to you about, and that means you won’t be able to have steak and eggs for breakfast for a while.
Your cholesterol is too high! But what, exactly, does that mean? Why do I have to watch my diet? What is the point of cholesterol, anyway? And why is it in all this delicious food? Let’s find out, shall we?Cholesterol is a waxy type of lipid, a substance that is insoluble in water, like oil or fat. Specifically, cholesterol is a type of fat that is made up of four interlocked rings of carbon called a steroid. We know steroids from watching sports, but not all steroids are responsible for building our muscles.
A steroid is simply a fat with a specific chemical structure, and that chemical structure allows the fat to do its job. Cholesterol is found in every single cell of our body.
Purpose of Cholesterol
Like all fats, cholesterol has a bad reputation, but it is essential to our diets. Cholesterol acts as the precursor for other steroids in our body.
When we eat cholesterol, we break it down and then use its parts to make things like testosterone and estrogen. It also acts as a precursor for vitamin D. I know what you’re thinking…
‘Wait, don’t I get vitamin D from standing out in the sun?’ Yep, you do, but your body can’t make vitamin D out of thin air. It uses sunlight to start a cascade of chemical reactions that break down cholesterol and use the parts to make the vitamin. Without cholesterol, you could stand out in the sun all day and still not make enough vitamin D for your body.
Cholesterol is also an important component of our cell membranes. It makes sure our cellular membranes work the way they should. It acts like a patch, keeping very tiny molecules from going in and out of our cells when they’re not supposed to.
Cholesterol also keeps the cell membrane nice and flexible, which allows our cells to do what they need to do. Without cholesterol, our cell membranes would be too stiff to form tissues like skin and muscle and would be leaking molecules like mad. That would be a very bad way to start the day!
How We Get Cholesterol
So where does cholesterol come from? Well, cholesterol is so important that we both make it and eat it. Every cell in our body can make its own cholesterol to some extent, but our livers are responsible for producing cholesterol in the largest amount.
A portion of our daily cholesterol is produced in liver cells, and our intestines, reproductive organs, and adrenal glands help out by producing a little bit themselves. This homemade cholesterol is then sent to whatever cell in the body needs cholesterol at that moment.We can also get cholesterol from our diets.
Animal products, including meats to cheeses to milk, all contain cholesterol. Basically anything that contains animal fat also contains a cholesterol source. Things like egg yolks, cheese, shrimp, beef, poultry and pork are all very high in cholesterol. Plants have a type of lipid that is almost like cholesterol, but not quite, so plants are not a significant source of cholesterol in our diet.
Dangers of Cholesterol
So if cholesterol is so important, why does it have a bad reputation? Well, this is where things get interesting. Notice that we both make and eat cholesterol. That means we have the chance of making or eating too much of it.
Not a big deal, right? We eat too much of lots of things and just end up getting rid of the excess. But that’s not how it works with cholesterol. Because cholesterol is a lipid, it doesn’t dissolve in water, so we can’t just get rid of it. We have to break it down into its parts and then get rid of it piece by piece. This takes a lot of coordination in our body. If we have too much cholesterol, it floats around in our blood waiting to be dealt with. Our bodies don’t have the time or resources to deal with all this extra fat, so the cholesterol ends up sticking to our arterial walls.
This causes a condition called atherosclerosis where our arteries are clogged by fat. Not a good scene!The main treatment for too much cholesterol is cutting out all high-cholesterol foods in our diet. I bet you know at least one person who has cut out red meat due to a blood test, right? But that’s only half the story. Since our body makes some of our cholesterol, even if you cut out all animal products from your diet, you could still end up with high cholesterol levels because of an overzealous liver. No bacon and you still have atherosclerosis? That’s just bad luck! These problems are becoming more and more common, which is why cholesterol just has a bad rap.
Cholesterol is a lipid composed of 4 rings of carbon and is an essential nutrient in human diets. It’s used in the body as a precursor for various steroids such as testosterone and estrogen and is used to form vitamin D.
It is so important that our body makes its own cholesterol and gets cholesterol from our diet, particularly from animal products. Too much cholesterol can end up causing atherosclerosis, which is when our arteries become clogged by fat.