Usually the HDL (high density lipoprotein), LDL (low density lipoprotein) and triglycerides are measured separately.
Hence, triglyceride is found in the blood.
(The 'experts' say high triglycerides increase your risk for cardiac event or disease.)
What are they?
The short answer is they are a fat--a lipid.
How do you accumulate them in your blood? From eating fat?
Nope. Carbohydrates are the culprit.
The simplified explanation:
When you eat carbohydrates it is converted--by your body--into glucose.
That glucose fuels your cells. Any excess glucose is returned to your liver.
Once there, the liver coverts that excess glucose to glycogen.
Glycogen fuels your muscles.
When you 'move' you use your muscles and they burn glycogen for fuel.
Your muscles store glycogen--so it'll be available when needed.
If you are a body builder with lots of muscle volume you'll need more glycogen than someone who is not.
What happens to the excess glycogen not used and not stored by your muscles?
It goes back--ta da--to your--you guessed--LIVER.
(Gee--I'm beginning to think the liver is a big deal--it works hard.)
The liver turns the excess glycogen into fat--i.e. triglyceride.
Some of that fat goes into fat storage.
(You'll find it on your tushie, your tummy..you know .)
And the rest?...it circulates in your blood, where it can gunk things up.
If you want to reduce the triglycerides in your blood, you must reduce your intake of carbohydrates.
You can do this by reducing your overall food intake--in other words quit eating excess calories.
You can do it by reducing the percentage of calories that come from carbohydrates--in other words eat more protein and fat--the good kind preferably.
And you can do it by moving those big muscles--which activity uses the stored glycogen--making room in your muscles for more to be stored. The more that goes to the muscles for storage the less there will be floating around in your blood stream.
Ahhh---the mystery of triglycerides solved.