LDL and VLDL Cholesterol


Maj West
For years, we’ve heard that LDL cholesterol is the “bad” cholesterol. Dr. Phillips, why is LDL considered bad?

Dr. Phillips
LDL is often referred to as bad cholesterol, although technically LDL is a low-density lipoprotein. Proteins bond with particles of cholesterol forming lipoproteins, which carry the cholesterol through your bloodstream. LDL is responsible for transporting about 75 percent of your body’s cholesterol out to your cells.

The problem with LDL is that it tends to collect on the arterial walls. These LDL deposits can then undergo a process called oxidation. In this case, oxidation is harmful because it makes it easier for LDL cholesterol to penetrate and inflame the arterial walls. In turn, the body’s immune system releases chemicals, called immune factors, to protect the damaged walls of the artery. These immune factors can actually add to the inflammation triggered by the LDL and cause even more damage to the arterial walls.

White blood cells and other particles are drawn to the inflammation, causing the buildup of plaque in the artery. Eventually the layers of cells that line the blood vessels are injured, and that causes the body to release more immune factors. Unfortunately, the immune factors that are released in response to the damaged blood vessels end up increasing the risk of blood clots.

The oxidized LDL also reduces the natural production of a substance that’s important for relaxing blood vessels, called nitric oxide.

Finally, as the plaques grow, the blood vessels become less elastic and narrower, reducing blood flow to vital organs.

Like LDL, high levels of VLDL, or very low-density lipoprotein, are often considered unhealthy. VLDL can build up in the walls of arteries and contribute to plaque formation. VLDL is comprised mostly of triglycerides, with little protein content. Its primary purpose is to carry triglycerides to fat cells where they can be stored.