Introducing Cholesterol

Recently I’ve had quite a few people ask me about cholesterol.  What is good and bad cholesterol?  What does it do?  What do the numbers my doctor measures really mean?  What foods in my diet will effect my cholesterol (either up or down)?

For many years doctors have used blood cholesterol as an indicator of the likelihood you will develop cardiovascular disease.  The higher your cholesterol, the more likely you are to develop cardiovascular disease.  In order to keep blood cholesterol low, doctors recommended a decrease in the amount of dietary cholesterol believing that a reduction in dietary cholesterol would automatically translate in to a reduction in blood cholesterol.  As it turns out blood cholesterol and your risk of subsequent cardiovascular disease has little to do with the cholesterol you ingest as part of your diet.   And despite its bad reputation cholesterol is essential for our survival.    

Meet the Players – Your Blood Fats

In order for cholesterol molecules to travel around your body, the fat (triglycerides) must combine with protein, forming a lipoprotein (lipid + protein) a.k.a cholesterol.  When these fats travel in the blood stream without a protein escort the are known simply as triglycerides.

High-density lipoprotein (HDL), the “good” cholesterol, is a molecule that contains more protein than fat.  Because of this high protein content, HDL can pick up additional cholesterol molecules (LDL) as it travels through the blood stream.  HDL carries the excess cholesterol it picks up in the blood stream to the liver for removal from the body.  Higher HDL levels lower the risk of having a stroke, heart attack or heart disease because they keep LDL blood levels in check and prevent the formation of large LDL plaques in the arteries and veins.  A healthy HDL level is greater than 60 milligrams per deciliter (mg/dL).

When the lipoprotein has more fat (triglycerides) than protein it has a low density and is called a low density lipoprotein (LDL).  LDL is the so called “bad” cholesterol. When LDL is found in excessive amounts in the blood stream it tends to build up in arteries as plaque, slowing blood flow.  A healthy LDL level is less than 70 milligrams per deciliter (mg/dL).

Very-low-density lipoprotein (VLDL) is a type of cholesterol that contains the highest amount of fat (triglyceride) and the least amount of protein.  Because of its high triglyceride level – and subsequent “stickiness” – an elevated VLDL level further increases your risk of coronary artery disease, which can lead to a heart attack or stroke.  Unfortunately, VLDL levels aren’t usually reported to you as a part of a routine cholesterol test because there’s no simple, direct way to measure VLDL cholesterol.  Instead, VLDL cholesterol is usually estimated as a percentage of your triglyceride value.  A normal VLDL cholesterol level is between 5 and 40 milligrams per deciliter.

Triglycerides are blood fats traveling without a protein escort. Having a high triglyceride level along with a high LDL cholesterol may increase your chances of having heart disease more than having only a high LDL cholesterol level.  A healthy triglyceride level is less than 100 milligrams per deciliter (mg/dL).

What Do Cholesterol and Triglycerides Do In My Body?

Cholesterol is a soft, waxy type of fat produced by your liver or ingested as part of your diet.  It is a vital part of each of your cells and is essential in the chemistry required for normal development and functioning.  Because of its importance, your body has the ability to make all the cholesterol it needs for each of these various functions.  However, some of the foods we eat also supply cholesterol to the body. In an effort to balance these two sources of cholesterol, your body adjusts the amount it produces each day.

On the cellular level, cholesterol is a part of cell membranes that helps each cell keep its shape and regulates what passes through the cell membrane into or out of the cell. In addition, cholesterol facilitates communication between cells and allows them to function as a group (think tissues and organs).

In the body cholesterol is a precursor to bile, some sex and regulatory hormones, and Vitamin D.  Produced by your liver, bile allows for the absorption of dietary fats as well as fat soluble vitamins like A, D, E and K from the foods we eat.  Cholesterol is used to produce sex hormones like estrogen, progesterone, and testosterone necessary for reproductive and developmental health.  It is also used to produce the regulatory hormones necessary to run your metabolism and build essential body tissue like muscle, skin and bone.  Lastly, cholesterol is required to produce the hormones cortisol and aldosterone which regulate your stress response, help manage blood sugar levels, aid in the function of the immune system, and regulate your fluid levels.

There is one more very important function cholesterol carries out in your arteries and veins.  When damage to your vascular tissue occurs, cholesterol, particularly LDL cholesterol, acts like a kind of spackle to cover any imperfections and to prevent the blood vessel from leaking blood into the surrounding tissue.

Triglycerides are one of the ways the body distributes energy.  When you eat, your liver converts any calories it doesn’t need to use right away into triglycerides and uses VLDL to distribute these triglycerides throughout the body.  Triglycerides transported to fat cells are taken in and stored for later use.  Triglycerides transported to muscle cells are used to provide energy.  If you regularly eat more calories than you burn, particularly “easy” calories like carbohydrates, you may have high triglycerides (hypertriglyceridemia) because you are taking in more food energy than your body can burn over time.

So, if cholesterol is a naturally-occurring fat which is fundamentally required for good health, how did it become the enemy?

Tune in next time for how cholesterol got its bad wrap….

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