To enter the cells and tissues where it’s needed, then, it hooks up with proteins, creating special transporters called lipoproteins. Think of these as submarine-like bubbles that carry cholesterol around the body. Some of these “submarines” are friends, but most are foes.
LDLs: Low-Density Lipoproteins
Low-density lipoproteins, or LDLs, are the primary foes—the archenemies, in fact.
LDLs carry most of the cholesterol (75 to 80 percent) in the blood, depositing it into the cells, including the arteries, There these particles contribute to the formation of plaque, which narrows the arteries. That reduces the amount of blood that can get through, diminishing the amount of oxygen that reaches the heart.
Some LDL types are more dangerous than others. Smaller, denser LDL particles are more damaging to blood vessels because it’s easier for them to cross the lining of the vessel and burrow into the vessel wall.
Most people won’t know what type of LDL they have because the tests to determine it are too expensive and complicated for the typical doctor’s office. If you already have CHD, or have a strong family history of CHD, and your doctor has sent you to a cardiac specialist, that doctor may run more detailed tests to better understand your risk. But it doesn’t matter much, as the focus remains the same regardless: Lower the
amount of LDL in your body.
So what’s the ideal LDL level? As you’ll read in Chapter 3, that depends on your personal history and other risk factors for CHD. But if you’re a man 45 or older or a wornan 55 or older and don’t have CHD, diabetes, hypertension, or a family history of premature CHD, and dont smoke, here’s what you should aim for (levels are measured in milligrams per deciliter, or mg/d-la deciliter is about 3 ounces)
| LDL level | Category |
|---|
| Less than 100 mg/dl | Optimal |
| 100-129 mg/dl | Near optimal |
| 130-159 mg/dl | Borderline high |
| 160-189 mg/dl | High |
| 190 mg/dl and above | Very high |
Everything from your weight to whether or not you smoke to your family health
history—even the amount of stress you’re under—affects your LDL level. Of course,
your diet makes a difference, too, particularly the types of fats you eat. You’ll read
much more about these fats in Chapter 4.
HDLs: High-Density Lipoproteins
High-density lipoproteins, or HDLs, are the good guys—the “garbage trucks” of the bloodstream, as described by C. Noel Bairey Merz, M.D., director of the Preventive and Rehabilitative Cardiac Center at Cedars-Sinai Medical Center in Los Angeles. HDLs typically transport about 20 to 25 percent of the cholesterol in your blood, carrying it away from tissues to your liver, which disposes of it. The more HDL in your bloodstream, the more artery-clogging cholesterol is being removed.
Research finds that for every 1 percent increase in your HDL level, your risk of a heart attack drops 3 to 4 percent. By comparison, a | percent drop in your LDL level reduces your risk of a heart attack just 2 percent. HDL is so beneficial that a high level may offer enough protection to cancel out a heart disease risk factor like having chabetes or being overweight.
Having low HDL, on the other hand, often signifies other problems. For instance, mary people with low HDL also have high levels of other dangerous blood fats, such as triglycerides and remnant lipoproteins (more on this later). That makes sense, since low HDL means fewer “garbage trucks” disposing of the “trashy” cholesterol. Low HDL can also be a sign of insulin resistance and metabolic syndrome, or Syndrome X. risks you’ll learn about in Chapter 2.
| HDL level | Category |
|---|
| Less than 40 mg/dl | Low (risky) |
| 10-59 mg/dl | Average (neutral) |
| 60 mg/dl and above | High (protective) |
Smoking, being overweight, being sedentary, and consuming a high carbohydrate diet (more than 60 percent of your calories) contribute to low HDL. So does a family history of low HDL. In fact, about half af HDL imbalances are due to genetics, Women are lucky in that they generally have a higher HDL level than men. But some doctors think women need these higher levels to remain healthy. and they suggest an HDL level even higher than 60 (the usual target) is most desirable for womens.
