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.

Some factors affecting your cholesterol level are out of your control.  As you get older, for example, your cholesterol level naturally rises.  Before menopause, women have lower total cholesterol levels than men of the same age, but after menopause women’s LDL levels tend to rise.  High blood cholesterol can also run in families.  Your genes affect how fast you make cholesterol and remove it from the blood.

However, there are things you can control.  “The clinical trial data are absolutely conclusive that lowering LDL cholesterol reduces your risk for heart disease,” Cleeman says.  “This is true both for those with high cholesterol levels and for those with average cholesterol levels.”

How do you know whether your cholesterol levels are where they should be?  In general, the higher your risk for heart disease, the lower your LDL level should be.  Cleeman says, “Your goal is individualized to your risk for a heart attack.  The number depends on your own risk factors.”  NIH has a heart disease risk calculator online at http://hp2010.nhlbihin.net/atpiii/calculator.asp, but you should also talk to your doctor about your risk factors and what your cholesterol levels should be.

“A person who has a cholesterol level higher than their goal LDL should follow the TLC program,” Cleeman recommends.  TLC stands for Therapeutic Lifestyle Changes.  It involves 3 things: changing what you eat, doing more physical activity and controlling your weight.

First, diet.  Saturated fat raises your LDL cholesterol level more than anything else in your diet.  It’s found mostly in meats and full-fat dairy products like whole milk, cheese and butter.  Another type of fat called trans fat raises cholesterol similarly, but makes up far less of the American diet.  Cholesterol in foods can also raise blood cholesterol levels, but its effect is not as strong as these fats’.  Saturated fat, trans fat and cholesterol are all listed on food labels so that you can choose foods with lower amounts to help lower your LDL cholesterol level.

Foods with soluble fiber—such as whole grain cereals, fruits and beans —help lower your cholesterol, too.  And some products, such as specially labeled margarines, orange juices and yogurts, contain the LDL-lowering compounds “stanols” and “sterols.”

Excess weight can increase your LDL cholesterol level.  “Fat tissue is not inert,” Cleeman says.  “It’s chemically active and produces all kinds of changes.”  One is raising LDL blood cholesterol levels.  Losing weight can help lower your LDL and total cholesterol levels, as well as raise your HDL and lower your triglycerides.

Regular physical activity can help you control your weight, lower your LDL and raise your HDL levels.  You should try to be physically active for at least 30 minutes a day.

If these lifestyle changes don’t lower your LDL cholesterol enough, medication can help.  “Medication should be added to lifestyle changes,” Cleeman advises, “not substituted for them.”  Lifestyle changes can bring benefits medications can’t.  While both can lower LDL, lifestyle improvements can lower blood pressure and other risk factors as well.

NIH’s National Heart, Lung and Blood Institute recommends that everyone older than 20 have their blood cholesterol measured at least once every 5 years.  Learn your numbers.  Then talk to your doctor about whether you need to take steps to alter your diet, lose weight or get more physically active to lower your blood cholesterol and stay healthy.