Biologique

Cancer, diabetes, depression, heart disease, stroke, Alzheimer's—these seemingly diverse diseases are increasingly thought to have a common denominator: inflammation. While our genetic predisposition for disease can't be changed, we can do something about this other major player.

Normally, inflammation is part of a healthy immune response, an orchestrated onslaught of cells and chemicals that heal injury and fight infection—think redness, pain, swelling. But the process also has a quiet, dark side. Chronic "hidden" inflammation occurs throughout the body when something kick-starts the immune system and disengages the shut-off button. What ignites the fires differs from person to person: repeated or prolonged infections, smoking, or gum disease, for example. Obesity, too, makes you prone to inflammation, as fat cells churn out inflammatory proteins called cytokines. But the end result is the same: An endless trickle of immune cells interferes with the body's healthy tissues, triggering genetic mutations that can lead to cancer or the bursting of plaque in an artery wall.

Scarier still, most people don't even know they're inflamed. There's not a reliable blood test yet to screen for inflammation. A test that measures an inflammatory marker called C-reactive protein is currently recommended for those at increased risk of heart disease, because high levels of CRP, for these folks, are associated with future heart attacks and strokes. But it's not used as a general screen because researchers still don't know what role CRP plays and whether it's truly a sign of increased risk of disease. What is clearly established, however, is that people with poor health habits tend to have higher levels of inflammation. And the latest science suggests that we can take action.

"In recent years, we've come to accept that inflammation plays a role in many chronic diseases, but it's about an imbalance—too many pro-inflammatory chemicals and not enough anti-inflammatory ones," explains Moise Desvarieux, an inflammation researcher at Columbia University's Mailman School of Public Health. Normally, hours after igniting the fires, the body shoots out anti-inflammatory substances to restore equilibrium.

Thus, staying well means having both systems in working order. Some promising indications that gaining a balance could be protective: According to a Harvard study published last year, cholesterol-lowering statin drugs reduced the risk of heart attacks and strokes in people whose blood analysis indicated excess inflammation, even though they didn't have high cholesterol. That's because statins probably have anti-inflammatory properties. And an August study published in the Journal of the American Medical Association found that colon cancer patients who took a daily dose of anti-inflammatory aspirin reduced their risk of dying from the disease by nearly a third. But experts say medications aren't the antidote to hidden inflammation. Aspirin, for example, can cause stomach ulcers and gastrointestinal bleeding; statins can cause severe muscle aches, and the risks of taking them for decades aren't known. Science suggests, though, that there are safer things you can do to keep from stoking the flames.

Assess yourself and take action. While being overweight raises your risk of inflammation, your body fat distribution may be even more important. "It's where your body puts the fat, on your waist as opposed to your hips and thighs, that indicates a pro-inflammatory state," says Carol Shively, a professor of pathology at Wake Forest University School of Medicine who has studied body fat distribution. Fat cells that accumulate near organs in your abdominal cavity tend to behave like little factories, responding to stress hormones that you produce when you're frazzled or overtired by pumping out chemicals of their own. The stress hormone cortisol "appears to bind to receptors on these fat cells, setting off a process that promotes the storage of fat and increases the number of fat cells," says Shively. "These extra cells then produce more chemicals that increase inflammation."