Cholesterol - Definition:
Cholesterol is a waxy, fatty substance found in the blood. Cholesterol is also present in every cell in the body including the brain, nerves, muscles, skin, liver, intestine and heart. Cholesterol isn’t all bad. In fact, cholesterol is an essential fat.
Cholesterol is essential to the formation of bile acids, vitamin D, progesterone, estrogens, androgens , mineralocorticoid hormones (aldosterone, corticosterone), and cortisol. It provides stability in every cell of our body.
Cholesterol can’t dissolve in the blood. It must be transported through bloodstream. To travel through the bloodstream, cholesterol has to be transported by helper molecules called lipoprotein, which got their name because they’re made of fat (lipid) and proteins.
Two important kinds of lipoproteins are low-density lipoprotein (LDL) and high-density lipoprotein (HDL).
HDL (High-Density Lipoprotein) – “The Good Cholesterol”
High density lipoproteins are the smallest and densest lipoproteins, and contain a high proportion of protein. They are synthesized in the liver as empty proteins and they pick up cholesterol and increase in size as they circulate through the bloodstream. This is a good cholesterol.
To counteract the disease process, a type of white blood cells macrophages go into artery walls and the apoA on the HDLs interacts with cholesterol transport proteins located in the outer cell membrane of the macrophages. Through this interaction, HDLs draw cholesterol out the macrophages and bring it back into solution in your blood and then to your liver.
Because HDL can remove cholesterol from the arteries, and transport it back to the liver for excretion, they are seen as "good" lipoproteins.
The other functions of HDL are:
- HDLs can deliver triglycerides and cholesterol to your liver, where the triglycerides can be used for energy and the cholesterol can be used in the formation of bile.
- HDLs can also participate in some of your immune response to pathogen. For examples, they can bind to and neutralize bacterial toxins and suppress the development of infections.
LDL (Low-Density Lipoprotein) – “The Bad Cholesterol”
LDL is called low-density lipoprotein because LDL particles tend to be less dense than other kinds of cholesterol particles. LDL collects in the walls of blood vessels, causing the blockages of atherosclerosis. Here’s how high amounts of LDL cholesterol lead to plaque growth and atherosclerosis:
- Some LDL cholesterol tends to deposit in the walls of arteries. This process starts as early as childhood or adolescence.
- White blood cells swallow and try to digest the LDL, possibly in an attempt to protect the blood vessels. In the proses, the white cells convert the LDL to a toxic (oxidized) form.
- More white blood cells and other cells migrate to the area, creating low-grade inflammation in the artery wall.
- Over time, more LDL cholesterol and cells collect in the area. The process creates a bump in the artery wall called plaque. Plaque is made of cholesterol, the body’s cells and debris.
- The process continues, growing the plaque and slowly blocking the artery.
An even greater danger than slow blockage is a sudden rupture of the surface of the plaque. A blood clot can form on the ruptured area. And that can lead to a heart attack.
How To Reduce LDL Cholesterol
Right lifestyle choices that can lower cholesterol and your overall risk typically start with a diet and exercise plan. LDL cholesterol-lowering diet is low in saturated fat and dietary cholesterol. Regular aerobic exercise lowers LDL cholesterol even further and increase HDL or good cholesterol. If diet and exercise don’t lower LDL levels enough, drug treatment may be need.
Remember, many factors besides cholesterol affect your risk of heart disease. Smoking, diabetes, high blood pressure, obesity and lack of exercise are also important contributors. Lowering LDL cholesterol is a good start, and it’s more important to reduce these other risk factor as well.