Cholesterol and Your Heart: What's New



Cholesterol and Your Heart: What's New?

by Christine Perry

Cholesterol. You've heard it's "bad for you," but why? Where does it come from? Does it do anything besides clog your arteries? This article will explain the relationship between high cholesterol and heart disease, describe the different types of cholesterol, and review several ways to lower a high cholesterol level, including exercise, a low-fat diet, and medication.

What is Cholesterol?

Cholesterol—judging from the thousands of food labels and TV commercials boasting "zero cholesterol!"—has quite a bad reputation. Much of it is not deserved. Cholesterol is a vital component of all cell membranes. It protects nerve cells and is the backbone for many hormones—among them cortisol, estrogen, progesterone, and testosterone. It is also used to make vitamin D and bile, a substance that helps digest fat.

Unfortunately, too high a concentration of cholesterol in the blood is associated with an increased risk of heart disease. Coronary heart disease (CHD) remains the #1 killer of both men and women in America. A high blood cholesterol is one of many risk factors for developing heart disease.

Where Does Cholesterol Come From?

Most of the cholesterol circulating in your blood is made in the liver from fat metabolism. The rest—about 20%—comes from the foods you eat. Dietary cholesterol comes from animal products such as meat, milk, cheese, and butter. It can also be made in the liver from saturated fat, which is found in animal products and some vegetable sources.

Types of Cholesterol

Cholesterol and fat are transported through the bloodstream in particles called lipoproteins, which are so named because they contain different proportions of lipid (fat) and protein molecules.

Chylomicrons are the largest lipoproteins, and they have the highest content of fat. Chylomicrons carry triglycerides (fat from the foods you eat) from the intestine to body tissues, where they are used for energy or stored as fat.

VLDLs (Very Low Density Lipoproteins) have a little bit more protein than chylomicrons. They carry triglycerides made by the liver to their destination in body tissues.

LDLs (Low Density Lipoproteins) are stuffed full of cholesterol. They hold about two-thirds of all the cholesterol in the blood. These particles, nicknamed "bad" cholesterol, are partially responsible for forming plaque (debris) along blood vessel walls. The more LDLs you have, the greater your risk of getting coronary artery disease—or a heart attack.

HDLs (High Density Lipoproteins) are known as "good" cholesterol. They're the protective counterparts to LDLs. HDLs contain a high proportion of protein, and their function is to scour the bloodstream, collecting excess cholesterol and transporting it back to the liver to be recycled or disposed of.

Cholesterol and Heart Disease

Increased levels of cholesterol in the blood can contribute to atherosclerosis, which is the gradual build-up of cholesterol, fat, and fibrous debris along the walls of your arteries. This build-up, called plaque, can accumulate enough to narrow the artery and stiffen the arterial wall, causing the heart to work harder to pump blood through.

Part of the plaque can also break off to form a clot, known in medical terms as a thrombus. Once released, clots can travel through the bloodstream through smaller and smaller vessels until they either dissolve or reach a point where they can't squeeze through, causing a blockage. If this blockage, called an occlusion, occurs in a coronary artery (one of several arteries that supplies the heart tissue with blood), the result is myocardial infarction, or heart attack. If the occlusion occurs in a cerebral (brain) artery, a cerebrovascular accident (stroke) takes place. The extent of the damage depends on the size of the blood vessel that is blocked.

What's Your Risk?

A high level of blood cholesterol is associated with an increased risk of heart disease. But unlike other risk factors for heart disease that you can't change or modify, such as age, sex, or a family history of heart disease, you can lower a high cholesterol level. That's why it is monitored so closely.

Check the risk factors below to see if they apply to you. The more risk factors you have, the greater your chances of developing heart disease.

|Unmodifiable Risk Factors |Modifiable Risk Factors |

|Men over age 45 |High blood pressure |

|Family history of heart disease |Cigarette smoking |

|Women over age 55 |Inactive lifestyle |

| |Obesity |

| |Type 2 diabetes |

| |High cholesterol |

Know Your Numbers

Cholesterol levels can be measured with a simple blood test. The table below shows the ranges that have been defined as "desirable," "borderline," and "high risk" for total cholesterol and the different types of cholesterol particles. However, the most important number is actually the ratio between total cholesterol and HDL cholesterol. The higher the ratio (high total cholesterol, low HDL cholesterol), the greater your risk for coronary heart disease. It is important, therefore, to know all the levels of your cholesterol and not merely the total cholesterol.

If you've had your cholesterol measured recently, see how it compares to the assessments below. Remember that the categories of “desirable”, “borderline”, and “high risk” apply to persons at average risk for heart disease and may not be appropriate for you. Your doctor can help assess the degree of risk associated with your particular cholesterol values:

|Lab Test |Desirable |Borderline |High Risk |

|Total Cholesterol |240 mg/dL |

|LDL Cholesterol |160 mg/dL |

|HDL Cholesterol |>39 mg/dL |n/a | ................
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