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VLDL

VLDL stands for Very Low Density Lipoprotein.  VLDL is made in your liver and it delivers fat (triglyceride) and cholesterol to different parts of your body.  Once its done its job some VLDL goes back to the liver and the remainder gets made into LDL.

LDL

LDL stands for Low Density Lipoprotein.  Its main job is to deliver cholesterol to different parts of the body.  Once LDL does its job it goes back to the liver.

VLDL and LDL play very important roles of delivering fat and chaolesterol around the body.  However, too much VLDL and LDL can harm you.  Normally a small amount of VLDL and LDL gets damaged while they're being shuttled around the body.  These damaged VLDL and LDL aren't recognized by the liver so they have to be removed by your white blood cells. 

If you make too much damaged VLDL or LDL then it can overwhelm your white blood cells to the point where they just stick in your arteries and turn into what is called a foam cell.  They send out signals for other white cells to come and help.  But these can also get overwhelmed and stick to the same area.  Over several years you have a buildup of these cholesterol loaded cells, some of which eventually die.  The cholesterol buildup can get so big that it often blocks much of the blood flow.  If this happens in the arteries in the heart it can lead to a heart attack.  If it happens in arteries in the brain it can lead to a stroke. 

We also have information about a lipoprotein related to LDL called Lp(a).  If you're interested please let us know and we may add it to the website if there's enough interest.

HDL

HDL stands for High Density Lipoprotein.  It comes out of your liver and intestine as a flat empty particle.  It travels around the body picking up excess cholesterol.  When it starts to get full it can get emptied in two ways:

1) One way is to recycle some of the cholesterol by transferring it to VLDL and LDL.  This transfer is handled by a special protein called CETP.

2) The other way is to take it to the liver which will dispose of it in the gut.  Once the HDL particle is emptied it can go back around the body and pick up more cholesterol.

 VLDL fact:

VLDL is mostly made up of triglyceride which can be used as energy by muscles or added to your body fat.  If your body clears triglyceride from VLDL slowly then there's a greater chance it can get damaged and won't be removed by your liver.  This frequently happens in people with diabetes.

LDL fact:

Some people have a rare disease, Homozygous Familial Hyper-cholesterolemia that prevents most of their LDL from being recognized by the liver.   These people can have cholesterol levels greater than 1,000 mg/dl and, if untreated, can have a heart attack before they are 10 years old!

HDL fact:

A lot of animals such as mice, dogs and horses don't have CETP.  These animals have very high HDL levels.  A few people have been described that don't have CETP either and they also have very high HDL levels of over 100 mg/dl.