Is Inflammation the Root of All Disease

Acute inflammation is characterized by the redness, heat, swelling, and pain that is the immune system's normal response to infection or injury. Immune cells congregate at the site so that they can overwhelm and dispose of infectious organisms or debris from injury. Thus healing takes place. But there's another kind of inflammation-low-grade, chronic, and "systemic." It's been getting a lot of attention lately.

Why it may be dangerous. The reason you hear so much about this kind of inflammation is that it may underlie a kind of "unified field" explanation of disease. That is, some researchers now believe that low-grade inflammation is associated with everything from heart disease and diabetes to Alzheimer's and arthritis, and may even be the cause of most chronic diseases. This is not an entirely new theory. Inflammation was implicated in cancer many years ago.

There is an easy way to test for inflammation, since it can prompt the liver to produce a protein in the blood known as C-reactive protein (CRP). Elevated levels of CRP often accompany or signal an increased risk of heart attack and stroke. This may help explain why many people who get heart attacks have normal blood cholesterol levels and no other identifiable risk factors. Scientists have been searching for the missing pieces of this puzzle, and inflammation might be one of them. It might even be the most important piece.

But "might be" is the operative phrase. Is inflammation a cause of disease or the result of it-or perhaps something that just goes along with it? No one can say for sure. However, we do know a lot about heart disease and its risk factors. High levels of LDL ("bad") cholesterol and low levels of HDL ("good") cholesterol are well-known risk factors, along with smoking, obesity, high blood pressure, family history, and being sedentary.

The link to heart disease. For many years heart disease was plaque building up in the walls of blood vessels and clogging them. But it is more complicated than that. Blood vessels are nothing like pipes-they are active tissue that absorbs cholesterol from the blood, and this may result in damage to the vessel walls. In trying to heal this damage, inflammatory cells come into the vessel walls. Among other things, they release many chemicals that may cause further damage. All of this is likely worsened by such factors as smoking and high blood pressure. Inflammation may contribute to the rupturing of plaque, which in turn triggers a blood clot, resulting in a heart attack or stroke.

How does this all get started? Bacterial infections like Chlamydia may trigger the inflammatory process, but so may the coronary risk factors named above-obesity, high blood pressure, unhealthy cholesterol levels, smoking, and so on. Many things contribute to the development of dangerous coronary plaque.

An intriguing aspect of the inflammation theory is the role aspirin plays in preventing heart attacks and ischemic strokes. Aspirin is the best-known nonsteroidal anti-inflammatory drug (NSAID). But at the low doses used to protect the heart (a quarter aspirin, or 81 milligrams, daily), it has a relatively small effect on inflammation. The benefit comes primarily from its ability to reduce the risk of blood clots. No other anti-inflammatory drug has been shown to reduce the risk of heart disease. In fact, some of these drugs (including Celebrex and ibuprofen) actually increase the risk of a heart attack, especially when used long term by people who already have cardiovascular disease.

Researchers have theorized that aspirin and other anti-inflam¬matory medications may help prevent other diseases, such as colon cancer and Alzheimer's. And some research supports these ideas. But for now, the known risk of adverse effects (such as gas¬trointestinal bleeding) outweighs these still-unproven benefits.

Should you get tested? The CRP test has been in use for some levels are checked, but so far is not routine. One version of the test, called the highly sensitive or hs-CRP test, is indeed helpful in people who have already had a heart attack, since high levels indicate risk of a recurrence. Still, there is no certainty about what your CRP level should be, and it is not even certain that bringing down elevated CRP will be beneficial. If you are at high risk for diabetes or heart disease, you don't need a CRP test to tell you that you need medical treatment. But if you are at borderline or intermediate risk for heart disease, talk to your doctor about testing. If your CRP level is high, your doctor may encourage you even more to take the steps below, or perhaps to take a statin or other medication.

How to ‘tamp down' inflammation. The same steps that help prevent cardiovascular disease may reduce chronic inflammation:

• Eat a moderate amount of fish. The omega-3 fats in fish can reduce inflammation. The American Heart Assocation encourages people with heart disease to consume 1 gram of omega-3s a day from fish or supplements. Omega-3s may also help reduce the inflammation associated with rheumatoid arthritis.

• Don't smoke; avoid inhaling other people's smoke.

• Talk to your doctor about low-dose aspirin to help prevent heart attack and stroke.

• If you're prescribed a statin, here's an added reason to take it. It serves double-duty-against cholesterol and inflammation.

• Control your blood pressure with diet, exercise, and medication (if needed). This will reduce your risk of heart disease and stroke. It may also lower your CRP level.

• If you are overweight, weight loss should also reduce inflammation and the risk of chronic disease. Obese people tend to have high CRP.

• It isn't certain that aerobic exercise reduces inflammation, but it might. Physically fit people tend to have lower CRP.

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