Your body can heal itself, which is pretty miraculous when you sit back and think about it. If you suffer a cut or infection—or if a disease, allergen or virus finds its way into you—your immune system reacts by sending specialized white blood cells to the affected area. These white blood cells can repair damage, stop the spread of infection or illness and in some cases eradicate the intruder. This whole response is called inflammation.
“Inflammation is an activation of cells and cell-derived components that have the job of fighting invasions, and in some cases just sponging up or clearing out damaged cells,” says Valter Longo, a professor of biological sciences at the University of Southern California and author of The Longevity Diet, a book that partly explores inflammation’s role in gut diseases.
Your body transports its immune cells primarily through your blood. And as blood rushes to the site of an injury or issue, that accumulated blood can produce heat, swelling and redness—all of which are hallmarks of inflammation, says Dr. Jason Ken Hou, an assistant professor of gastroenterology at Baylor College of Medicine.
Without inflammation, your body would be largely defenseless when faced with injury or illness. But not all inflammation is helpful.
“In disease states, the good inflammation becomes chronic, or at least dysfunctional,” Longo says. Inflammation either sticks around when it should dissipate, or the immune system directs inflammation at something that’s not really a threat.
For example, inflammation can worsen the stiffening of arteries and promote plaque accumulation in some people with high cholesterol, high triglycerides and other risk factors for heart disease. These risk factors can irritate the inner lining of the blood vessels and cause an inflammatory response, says Dr. Michael Miller, a professor of medicine and director of the Center for Preventive Cardiology at the University of Maryland School of Medicine. In some cases, Miller says, inflammation increases the risk for dangerous clots, rather than eradicate the problem.
Many gut disorders are also related to inflammation overload. “In Crohn’s disease and ulcerative colitis, which are inflammatory bowel diseases, the immune system is primed and inflammation is turned on inappropriately,” Hou explains. This can damage the lining of the intestine, and that damage can allow gut bacteria to penetrate, which leads to more inflammation, he says.
In the case of autoimmune diseases, chronic inflammation can target parts of a person’s own body. Lupus and rheumatoid arthritis are two examples. When it comes to lupus, the immune system mistakenly attacks its own tissues. In rheumatoid arthritis, the immune system produces inflammation that wears down the joints.
Runaway inflammation has also been implicated in the formation of Alzheimer’s disease. And there’s ample evidence that stress-related hormones—namely cortisol—can further instigate inflammation and fuel some of these chronic conditions. Some research has also linked inflammation to mental health disorders like depression.
What’s not clear in many cases is what causes inflammation to run amok in the first place. “It’s a chicken and egg debate,” Longo says. While some researchers believe inflammation and immune system malfunction occur first and create problems, he and many others believe that out-of-control inflammation begins in response to some injury or issue.
Regardless, there’s no easy way to deal with overabundant inflammation. Miller says that stress-reduction techniques may mellow out inflammation in some cases. Depending on the type of inflammatory issue a person is dealing with, doctors may also prescribe anti-inflammatory drugs. “We use these medications to help calm down the immune system,” Hou says. But down-regulating inflammation is a delicate dance; too little inflammation can let infections or illnesses run rampant.
The good news: the more experts understand the role of inflammation in disease and illness, the more they’ll develop tools and techniques to keep that inflammation under control.