The word “inflammation” might conjure up images of a swollen ankle after some missteps on a long hike. But inflammation has also emerged as a key factor in serious diseases, such as cardiovascular disease, cancer, Alzheimer’s disease, obesity, diabetes, and a variety of infectious diseases including HIV/AIDS. We asked Akiko Iwasaki, PhD, professor of immunobiology at Yale School of Medicine about acute and chronic inflammation, and how they work with homeostasis, which is the process our bodies naturally use to maintain the critical functions that keep us alive, including heart rate, breathing, and glucose and insulin levels. A better understanding of inflammation, Iwasaki explains, can help provide clues for developing therapies for inflammatory diseases. Read on to find out more—and to ensure your health and the health of others, don’t miss these Sure Signs You’ve Already Had COVID.

When scientists and researchers discuss inflammation, they’re referring to the body’s natural way of defending itself against tissue damage, as well as against viruses and bacteria. It’s a defensive response governed primarily by the immune system, which dispatches white blood cells to the affected sites, resulting in redness and swelling or symptoms such as fever. But they’re also talking about how, sometimes, the immediate, or acute, immune response isn’t enough to clear those viruses. At that point, the inflammation becomes chronic, resulting in harm to the body. “In those conditions, such as infection with HIV or hepatitis virus or long COVID, there may be a persistent viral reservoir that’s causing the chronic inflammation,” explains Iwasaki. “And in that case, the inflammation itself becomes the enemy,” she adds.

“Acute inflammation happens as a part of our defense mechanism to clear pathogens. So when a virus or bacteria invades us, we need to quickly mount an acute inflammatory response to get rid of the pathogen. Sometimes that acute immune response isn’t enough to get rid of the pathogen. That’s when we elevate the level to the adaptive immune response. That’s when you involve specific lymphocytes T and B cells to fight off the infection,” Iwasaki explains. “Inflammation is a necessary process for dealing with pathogens, but sometimes it can also turn against us,” she says.

“Chronic inflammation happens because the body fails to get rid of the cause of the inflammation such as viruses and bacteria in those conditions, such as chronic infection with HIV or hepatitis virus or long COVID. In which case we believe there may be a persistent viral reservoir that’s causing this chronic inflammation. The inflammation itself becomes the enemy,” says Iwasaki. “Even though inflammation evolved to counter pathogens, it’s also engaged by other causes. And so having an excess amount of fat, for example, alone, is able to trigger the immune system and induce the chronic inflammatory response that then fuels further problems to happen because the body’s sort of trying to fight off a non-existent infection and therefore it can sort of engage a chronic state of inflammation,” Iwasaki explains.6254a4d1642c605c54bf1cab17d50f1e

“I can’t think of a disease which doesn’t involve inflammation, but we are now learning more and more about the physiological role of inflammation,” says Iwasaki. “Homeostasis ensures that we have a normal operation of different physiological functions like heart rate breathing and glucose levels or insulin levels. Those two systems, the inflammatory system, and the homeostasis work together to maintain each other. Sometimes the internal response has to override the homeostatic response. That includes things like adaptation to different diet—immune cells are now known to be able to sense differences in dietary conditions and adapt the intestine for future, um, absorption of nutrients, this kind of events that are not necessarily at all related to pathogens, but for maintaining physiology inflammatory responses are integral in order to maintain health,” Iwasaki adds.

Experts say that a number of lifestyle changes can reduce inflammation, and the most effective is weight loss. According to a 2018 review of studies, losing weight can reduce the amount of inflammation in your body, and reducing the number of calories you consume daily has an anti-inflammatory effect, no matter what diet you follow. 

Other changes that can help reduce inflammation include:

• Eating a diet that’s low in added sugar, high fructose corn syrup, processed foods and simple carbs, and rich in fruits and vegetables, fiber, nuts and omega-3 fatty acids (the kind found in fatty fish like salmon)
• Reducing your intake of saturated and trans fats
• Getting regular exercise
• Reducing stress
• Following your doctor’s advice about routine testing and keeping your heart healthy, and consulting them if you have questions or concerns

And to get through this pandemic at your healthiest, don’t miss these 35 Places You’re Most Likely to Catch COVID.