Why You Should Keep Your Blood Cholesterol Level in Check
NIH NEWS
You’ve heard that you should lower your cholesterol, but do you know why? Sometimes we tend to ignore advice when we don’t understand the reasons. That’s why it’s important to learn what cholesterol is, what it does in your body and why you need to make sure too much isn’t flowing in your blood.
Cholesterol is a waxy, fat-like substance that your body needs to function normally. It’s used in the cell membranes that surround cells throughout your body. You also use cholesterol to make important chemicals, including hormones, vitamin D and the acids that help you digest fat.
“Cholesterol has a variety of uses in the body that are very important,” says Dr. James Cleeman, coordinator of NIH’s National Cholesterol Education Program, “but the body makes all it needs and we don’t need to get any more from our food.”
In fact, when the level of cholesterol in the blood gets too high, it can start to cause trouble. The landmark Framingham Heart Study, funded by NIH, first showed that the higher the cholesterol level in your blood, the greater your risk for heart disease—the number 1 killer of Americans, both women and men.
What’s the connection? Well, there are 2 forms of cholesterol in your blood: LDL and HDL. When there’s too much cholesterol in your bloodstream, the cholesterol from LDL can build up in the walls of your arteries. Along with fats like triglycerides and other things in the bloodstream, it forms a growing “plaque” that bulges out of the artery wall and can begin to block blood flow—a process called atherosclerosis. Problems get even worse if a plaque bursts and a blood clot forms on top, which can block an artery.
“Where LDL cholesterol does its most harm,” Cleeman says, “is in the walls of the arteries going to the heart—the coronary arteries.”
That’s why a high LDL cholesterol level increases your risk for heart disease. Like any muscle, the heart’s own muscle needs a constant supply of oxygen and nutrients, delivered by the blood in the coronary arteries. When these arteries become narrowed or clogged by plaque, the result is coronary heart disease. If the blood supply to a portion of the heart is completely cut off, the result is a heart attack.
HDL cholesterol seems to have the opposite effect of LDL; higher HDL levels are associated with a lower risk for heart disease.