Good and Bad Cholesterol
You may be wondering what all the fuss is concerning good and bad cholesterol. Is good cholesterol actually good or is it merely a “not-so-bad” form of cholesterol that isn’t as harmful as bad cholesterol? It is actually the former. "Good" cholesterol has beneficial qualities and is not merely less "bad." Read on below to find out why.
Water solubility. The chemical structure of cholesterol makes it only minimally soluble in water (or blood). This causes a problem, which is solved by carriers called lipoproteins. As the name implies, lipoproteins contain both lipid and protein components. They are able to effectively ferry cholesterol from place to place in the body via the bloodstream.
This is where the misnomers “good” and “bad” cholesterol come in. Good cholesterol is actually referring to carrier proteins that ferry cholesterol away from the body.Conversely, bad cholesterol are carrier proteins that ferry cholesterol to the body.
Why LDL is bad cholesterol? In the exogenous pathway of lipid metabolism, large lipoproteins called chylomicrons shuttle dietary triglyceride fats (TGs) and cholesterol from absorbed intestines to the liver. In the endogenous pathway, TGs and cholesterol is then carried by very low-density lipoproteins (VLDL), intermediate-density lipoproteins (IDL) and low-density lipoproteins (LDL) from the liver to various parts of the body using the blood stream. Simply stated, these VLDLs and LDLs deposit fat to places in the body, including the blood vessels. This is the key to many of the problems caused by high levels of LDL. Deposition of fats can play a role in the hardening and narrowing of the lumen of a blood vessel. When the blood vessel is sufficiently occluded (or even totally blocked), neighboring organs and regions that rely on a consistent and fresh blood supply are affected. For example, when the blood supply to the heart (coronary arteries) is blocked, heart attacks can result. When the blood supply to the brain is blocked, strokes can occur. For all these reasons, LDL has come to be known as “bad cholesterol.”
Why HDL is good cholesterol? High-density lipoproteins (HDL) transport TGs and cholesterol from the body back to the liver where elimination can occur. This includes shuttling fats from blood vessels. Since fatty buildup of cholesterol in the blood vessels causes many diseases, it has become clear that HDL acts to actively protect the body from disease by removing the cholesterol fat deposits on the body. This helpfulness has contributed to HDL being dubbed “good cholesterol.”
As you can see, the difference between good and bad cholesterol is a misnomer that has nothing to due with cholesterol. Cholesterol itself is structurally the same in HDL as it is in LDL. The difference between good and bad comes from the roles the carrier lipoproteins (HDL, LDL) play in transporting cholesterol to the body (bad) or from the body (good).