Inflammation and C-Reactive Protein

role in damaging the arteries by interfering with an enzyme involved in nitric oxide production. As you learned earlier, less nitric oxide means artery walls that attract more plaque-forming gunk. CRP also seems to be a marker for metabolic syndrome, a risk factor you’ll read more about later in this chapter.

Another marker of inflammation is a molecule called interleukin-18 (IL-18). A four-year German study on patients with CHD found that those with high levels of this molecule were three times as likely to die from heart disease as those with low levels, Earlier studies had linked high levels of IL-18 to quicker buildup of plaque and more unstable plaque. The results are still preliminary, researchers warn, and the test for IL-18 is too complex for the typical doctor’s office.

Stil, given the evidence on CRP and IL-18, doctors now suspect that inflammation plays such a powerful role in heart disease that it trumps even high cholesterol as ansk factor—although you can’t treat one and ignore the other, because they are linked. LDL increases inflarumation, and inflammation generates free radicals, which oxidize the LDL particles and accelerate the formation of plaque. Many of the same factors that increase inflammation—such as obesity, diabetes, and metabolic syndrome—also increase cholesterol.

By the Numbers

CRP testing is becoming increasingly cormmon as doctors are finding that people with elevated CRP—even if their LDL is below 150—may benefit from lifestyle changes and statin drugs. If you have high levels of CRP and high cholesterol, your risk of heart attack and stroke is nine times that of someone with normal levels of both.

The risks of heart attack and stroke begin to rise with a CRP level as low as 0.55 milligram to 0.99 milligram per liter. Above 2.5 milligrams your risk is twofold or even four fold. Ask for the high-sensitivity CRP test (hs-CRP) at your next checkup. It costs about $20 and is widely available. The standard CRP test, used for diagnosing conditions such as arthritis and inflammatory bowel disease, simply isn’t sensitive enough.

Despite CRP’s value in predicting heart disease risk, it will never be used by itself, doctors say, because it may be elevated in people with other forms of inflammation (such as arthritis) whose CHD risk is normal.

How the Plan Can Help

The good news is that CRP levels seem to predict a heart attack six or eight years in the future. That’s plenty of time to modify your lifestyle (and, if necessary, take medication). One imperative is quitting smoking. Smoking inflames the arteries and is associated with higher levels of CRP. If you smoke, we strongly suggest you quit. Ask your doctor for advice on how to do it.

The Plan will help reduce your CRP level through:

Supplements. Fish-oil supplements help reduce inflammation throughout the body. This action may be one reason studies find that people taking fish-oil supplements are less likely to die from a heart attack than those who don’t take the supplements.

Aspirin. The Plan recommends a daily aspirin for people at increased risk for heart disease. In a seminal 1998 study on CRP and heart disease risk, researcher Paul M. Ridker, M.D., and his colleagues found that men with the highest levels of CRP reaped the greatest benefits from taking aspirin.

Weight loss. When Dr. Ridker evaluated the connection between weight and CRP, he found that the more overweight you are, the higher your CRP level. That’s not surprising, since fat cells are a major source of interleukin-6, a protein that plays a key role in inflammation. More interleukin-6 means a higher CRP level. The Plan will help you lose weight through healthful eating and exercise.

Exercise. A study published in August 2002 found that the more active people were, the lower their CRP levels. The study, which evaluated data from a national health and nutrition survey of nearly 14,000 people, reported that just 8 percent of vigorous exercisers had elevated CRP levels, compared with 13 percent of moderately active and 21 percent of sedentary adults. The Live /t Down Plan recoramends moderate physical activity four or more days a week