Triglycerides are the most common form of fat found in our bodies. The word triglyceride describes this fat's chemical structure. Its chemical backbone is made up of glyceride (a carbon, oxygen, and hydrogen molecule) with three (tri) attached fatty acid chains. It is also the most common form of fat in vegetable oil and animal fat.
Triglycerides are very important as they serve as one of our main energy reserves. They have more than twice the energy as an equivalent amount of carbohydrate or protein. Triglycerides can be absorbed from food through the intestine. Fat cannot freely circulate in the blood, and when we absorb triglycerides or fatty-acids in food, they are repackaged as triglycerides in a fat-protein transporter called a chylomicron. Our body can also make its own triglycerides when we eat more energy than we use, and the energy consumed does not necessarily have to come from fat. The liver can create a fat-protein transporter called a VLDL (very low density lipoprotein) to carry triglycerides around. If we don't readily use up these high energy fats, then our body stores these triglycerides in a very specific energy depot such as in the waist of men or the thighs of women. That's right...unused triglycerides are the main component of our fat cells.
You may now be thinking, "Thanks for the biochemistry lecture. Now I know why I can't fit into last year's bathing suit." But what else do I need to worry about with high triglycerides?"
Triglycerides can be measured in the blood and are routinely reported on a standard lipid panel. The levels are expressed in mg/dl (milligrams/deciliter) in the US. Normal levels are <150mg/dl, borderline high 150-199mg/dl, high 200-499mg/dl, and very high >500mg/dl. In general, hypertriglyceridemia does not cause immediate problems. If levels are very high (>1,000mg/dl), then acute pancreatic injury can occur. This is characterized by abdominal pain, nausea, and loss of appetite. One clue to these high levels is that blood drawn from these people resembles a full fat Starbuck's latte. They may even have fatty deposits in their skin called xanthomas.
The main concern about hypertriglyceridemia is its contribution to heart disease. Most agree that high triglycerides moderately contribute to the development of heart disease and heart attacks. In fact, the above listed values of normal and high levels of triglycerides are based upon increasing heart disease risk. Also, there is some, but not a lot, of evidence linking hypertriglyceridemia to stroke. What we are not so clear on is the mechanism by which high triglycerides cause heart disease. There is some evidence that triglycerides, or rather their fat-protein transporters like VLDL, directly contribute to blood vessel damage. Other evidence supports a more indirect role such as its association with low HDL levels, insulin resistance, and increased blood clotting. Regardless of the mechanism, treatment of hypertriglyceridemia is now generally recommended to prevent heart disease.