What is cholesterol and where does it come from?
Cholesterol is in a group of compounds known as lipids. Lipids are “fatty” substances that are hydrophobic or simply, they do not like water. If you have ever put oil in water you can see the hydrophobic action of lipids when they form small droplets in the water. Lipids, including cholesterol, are an important part of our body.
Cholesterol is needed for the body to be able to function. Cholesterol is actually a component of our cell membranes and is important in the production of certain hormones. One asks the question then, how is there “good” and how is there “bad” cholesterol?
To start with, the vast majority of cholesterol that is found in our blood stream is actually produced by the body itself. Specifically, cholesterol is manufactured by the liver. We also get cholesterol from out diet. The amount of cholesterol that our body produces and the amount we absorb from our diet is variable, and based on each person’s genetics. Cholesterol from our diet comes from foods that are derived from animals. For example:
This is why when you speak with your physician, he/she may recommend a low cholesterol diet. They may also speak with you about certain medications which can help reduce the amount of cholesterol your body makes or the amount you absorb from your diet. How then, does this translate to “good” and “bad” cholesterol.
What is “bad” and what is “good” cholesterol:
When we talk about the “good” and the “bad,” we are simply referring to cholesterol that is either transported from the liver to your tissues or from the tissues back to the liver. A simple analogy is dump trucks in the blood stream. There are trucks that are hauling cholesterol away from the liver to your tissues and ones hauling cholesterol back to the liver from your tissues.
The dump truck that hauls cholesterol to your tissues and away from the liver is known as LDL or low density lipoprotein. This is known as the “bad” cholesterol. At higher LDL levels, and in light of certain conditions such as diabetes, the cholesterol can be deposited in your blood vessel. Over time, this cholesterol can start to form a plaque in the wall of your blood vessel (artery). This plaque can enlarge and impede blood flow but can also rupture and spontaneously clot your blood vessel. We worry about this when the blood vessels of the heart are affected. Limited blood flow to the heart muscle can cause recurrent chest pain known as angina. Sudden loss of blood flow to the heart muscle results in a heart attack (myocardial infarction). How then does your “good” cholesterol come into play.
HDL, or high density lipoprotein (the good guy), is simply the dump truck that can haul cholesterol out of your blood vessel and carry it back to the liver where it is broken down. The more dump trucks you have carrying cholesterol away from the blood vessel the better. This can decrease the rate at which you form plaques or can assist in keeping you from building plaques in your arteries. This is why we shoot for low LDL and high HDL. Diet and exercise are key to lowering LDL and increasing HDL.
What other component of the lipid profile is important?
The other important component of the lipid profile is triglycerides. Triglycerides act as a fatty fuel source for the body. Triglycerides are important in relation to LDL. When you have high triglyceride numbers, they affect the size of your LDL cholesterol. Essentially, high numbers of triglycerides make your LDL smaller. When your LDL becomes smaller, it takes less effort for it to “squeeze” into your blood vessel. And in turn will make it easier for your LDL to form plaque in your blood vessel. Lower numbers of triglycerides and lower LDL numbers minimize the risk of heart disease.