01
Cholesterol Is an Essential Substance for the Human Body
When people hear the word "cholesterol," many immediately think that cholesterol is bad. In fact, cholesterol itself is not harmful. It is an essential substance for the human body and an important component of blood lipids.
Cholesterol is not only an important raw material for the synthesis of adrenal corticosteroids, sex hormones, and vitamin D, but also a major component of cell membranes. It plays essential roles in intracellular substance transport, nerve signal transmission, and other physiological processes.
There are two major sources of cholesterol in the human body.
The first is dietary intake, which accounts for approximately 30%. In healthy individuals, dietary cholesterol mainly comes from foods such as animal organs, egg yolks, cream, and meat.
The second is endogenous cholesterol synthesized by the liver, which accounts for approximately 70%. The human body can synthesize around 1 gram of cholesterol on its own every day.
Therefore, elevated cholesterol levels can be influenced by both internal and external factors:
Internal factors include genetic and disease-related factors. For example, people with a family history of hyperlipidemia may have a higher risk of developing elevated cholesterol. Liver and biliary diseases may also affect cholesterol metabolism.
External factors are mainly related to lifestyle habits. Obesity, long-term smoking and alcohol consumption, and a high-fat diet are all risk factors associated with elevated cholesterol levels.
02
"Good Cholesterol" vs. "Bad Cholesterol"
Cholesterol is often classified into two major types according to the lipoproteins that carry it: high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C).
■ "Good Cholesterol"
High-density lipoprotein cholesterol (HDL-C) is commonly referred to as "good cholesterol."
HDL helps transport excess cholesterol from the bloodstream back to the liver, where it can be metabolized and eliminated from the body. This helps reduce excessive cholesterol accumulation in blood vessels, potentially lowering the risk of atherosclerosis and cardiovascular and cerebrovascular diseases.
However, higher HDL-C is not necessarily always better. Some studies suggest that extremely high HDL-C levels may also be associated with increased mortality from certain diseases.
■ "Bad Cholesterol"
Low-density lipoprotein cholesterol (LDL-C) is commonly referred to as "bad cholesterol."
Excess LDL-C can accumulate in the arterial walls and contribute to the formation of atherosclerotic plaques. If a plaque ruptures, a blood clot may form and obstruct blood flow, potentially leading to conditions such as coronary heart disease, stroke, myocardial infarction, ischemic stroke, and sudden cardiac death.
Therefore, when people commonly talk about "high cholesterol," they are often referring to an elevated level of LDL-C, or "bad cholesterol."
In addition to these risks, elevated LDL-C and dyslipidemia may be associated with other health problems. Abnormal lipid metabolism can contribute to cardiovascular risk and may also be associated with metabolic and vascular disorders. Cholesterol is also involved in bile metabolism; excessive cholesterol saturation in bile can contribute to cholesterol gallstone formation and may lead to complications such as acute cholecystitis or cholangitis.