So we thought we’d kick off this cholesterol series by explaining exactly what cholesterol is and what role it plays in our bodies (yes, it does have a purpose).

What is cholesterol?

Most people think of cholesterol as a fat, but it’s actually what’s called a sterol, a type of alcohol. Cholesterol is an essential component of cell membranes in animals and is required to establish proper membrane permeability and fluidity. It also plays a very important role in the hormonal systems of the body for the manufacture of bile acids (which digest fats), steroid hormones (such as estrogen and testosterone), and Vitamin D.*

Cholesterol’s role in the human body

Believe it or not, cholesterol is a repair molecule. When arterial walls are damaged, cholesterol rushes to the scene for membrane synthesis and repair.

Cholesterol moves around the body via two lipoproteins – low-density lipoprotein (LDL), what people call “the bad cholesterol,” and high-density lipoprotein (HDL), what people call “the good cholesterol.” So you see, LDL and HDL are not forms of cholesterol at all, but rather vehicles that ferry cholesterol around to different parts of the body – something that many people don’t realize.

HDL and LDL are actually lipoproteins that carry cholesterol to and from the liver

The human body needs both LDL and HDL because they have different transportation roles. LDL carries cholesterol from the liver, where it is produced, to the tissues, and HDL carries cholesterol from the tissues back to the liver. This is why LDL gets the “bad” characterization – because it shows up in damaged arteries that are in need of repair. Whereas HDL is viewed as “good” because it carries cholesterol away from damaged areas.

But in the words of Nina Planck in her book Real Food, “Just because you see firefighters at burning buildings does not mean they start fires.” Cholesterol shows up in injured arteries because it’s there to repair them, and LDL is the vehicle by which it arrives on the scene. Cholesterol isn’t causing the damage – it’s fixing it!

So what’s actually causing the damage? Other substances in the body (or the lack thereof), which we’ll be discussing in detail in a subsequent post. Stay tuned…

* Source: Wikipedia’s Cholesterol entry.