Do you know what cholesterol is?
Did you know that cholesterol can be classified as “good” and “bad”?

Let Dr. Wei-Cheng Luo from the Division of Metabolism and Endocrinology guide you in understanding cholesterol.

In internal medicine clinics, physicians often carefully explain laboratory reports, and cholesterol testing is one of the most common examinations. Today, let's learn about what “bad” cholesterol is.

Cholesterol in the human bloodstream comes partly from food and partly from synthesis in the liver. High-density cholesterol, known as good cholesterol, acts like a “cleaner” of the blood vessels by helping remove excess cholesterol from the circulation.
In contrast, low-density cholesterol, also known as bad cholesterol, can cause atherosclerosis when its levels are too high.

The yellow particles represent low-density lipoproteins (LDL) in the blood. Lipoproteins carry cholesterol through the bloodstream to supply tissues throughout the body. However, when cholesterol levels become too high, cholesterol can enter the arterial walls, leading to atherosclerosis and the formation of atherosclerotic plaques. In some cases, these plaques may rupture, forming blood clots that can result in life-threatening myocardial infarction (heart attack) and stroke.

First, low-density cholesterol passes through the vascular endothelial cells and binds to proteoglycans in the middle layer of the arterial wall. Over time, this cholesterol becomes oxidized and activates the immune system, triggering macrophages to ingest large amounts of cholesterol. Eventually, the macrophages undergo cell death, and layer by layer, this accumulation forms atherosclerotic plaques. These plaques are like time bombs—when they rupture, they trigger blood coagulation, leading to heart attacks and strokes.

After understanding the mechanism by which bad cholesterol causes atherosclerosis, remember to take your lipid-lowering medications as prescribed when they are prescribed to you, in order to prevent cardiovascular events.