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Everybody knows about the dangers of high cholesterol. While it is not precisely accurate that cholesterol clogs arteries and the type of cholesterol that is actually dangerous is almost never measured by doctors, the reality is that cholesterol and inflammation together are a major factor in cardiovascular disease.
Almost nobody knows about the dangers of high triglycerides. There are no billion-dollar blockbuster drugs for treating high triglycerides, no advertising campaigns warning us all of the dangers of high triglycerides, and our doctors aren't going to get kickbacks from pharmaceutical sales people for keeping our triglyceride levels low. The reason many people have heart attacks and strokes even when their cholesterol numbers are "perfect," however, usually has a lot to do with excessive levels of triglycerides.
What Are Triglycerides?
Triglycerides are the body's main way of storing unused calories. A triglyceride is a chemical combination of glycerol, which the body manufactures from carbohydrates, and fatty acids, which the body releases from fat. Triglycerides can be broken down to release glycerol so the body can make glucose to fuel the brain, or into fatty acids to fuel the muscles.
The small intestine breaks down triglycerides in food so they can be repackaged with cholesterol before they enter the bloodstream. These bundles of cholesterol, triglycerides, and a protein "balloon" containing them to make them soluble in the watery blood plasma are known as chylomicrons.
It's accurate to think of chylomicrons as really big chunks of cholesterol and fat. Chylomicrons are so large, in fact, they don't get stuck in the linings of arteries. Some chylomicrons are used by muscles for quick energy, and others are broken down in the liver into slightly smaller chunks of mostly-cholesterol, especially very-low density lipoprotein or VLDL cholesterol.
When Are High Triglycerides a Problem?
There is a general misconception that high triglycerides do not contribute to the artery-clogging process known as atherosclerosis. Actually, they do. If you have normal cholesterol but high triglycerides, you still have a similar risk of atherosclerosis. You're just a lot less likely to do anything about it.
The way triglycerides increase the risk of heart disease has to do with the fact that chylomicrons are not completely consumed as they pass through the bloodstream. They give up more glycerol (the sugar-derived portion) than cholesterol. The cholesterol left behind in a chylomicron may be processed by the liver into small bits of cholesterol known as high-density lipoprotein or HDL cholesterol, or it may be absorbed by "foam cells" from the immune system lining the arteries. When triglycerides are absorbed into foam cells, they are just as dangerous as cholesterol.
Of course, if your immune system has not activated foam cells in the lining of your arteries, you don't get atherosclerosis. That is the reason why people who have high triglycerides or high cholesterol sometimes do not get heart disease, and people who have normal triglycerides or normal cholesterol sometimes do.