April, 2020
Understanding acute and chronic inflammation
The saying "too much of a good thing" applies to much of life, but especially to inflammation.
"People think inflammation needs to be stomped out at all times, but it plays an essential role in healing and injury repair to keep your body safe and healthy," says Dr. Robert H. Shmerling, medical editor of Understanding Inflammation from Harvard Health Publishing and an associate professor of medicine at Harvard Medical School. "Some inflammation is good. Too much is often bad. The goal is to recognize when inflammation is simply doing its job, and when it can potentially cause problems."
Signs of inflammation are like a car's dashboard engine light. It tells you that something is wrong. But your response is not to take out the bulb, because that's not the problem. Instead, you look at what caused the light to turn on. "It's the same with inflammation," says Dr. Shmerling. "It's telling you that something bigger is going on that requires attention."
Acute inflammation is how your body fights infections and helps speed up the healing process," says Dr. Shmerling. "In this way, inflammation is good because it protects the body." This process works the same if you have a virus like a cold or the flu.
In contrast, when inflammation gets turned up too high and lingers for a long time, and the immune system continues to pump out white blood cells and chemical messengers that prolong the process, that's known as chronic inflammation. "From the body's perspective, it's under consistent attack, so the immune system keeps fighting indefinitely," says Dr. Shmerling.
When this happens, white blood cells may end up attacking nearby healthy tissues and organs. For example, if you are overweight and have more visceral fat cells — the deep type of fat that surrounds your organs — the immune system may see those cells as a threat and attack them with white blood cells. The longer you are overweight, the longer your body can remain in a state of inflammation.
Research has shown that chronic inflammation is associated with heart disease, diabetes, cancer, arthritis, and bowel diseases like Crohn's disease and ulcerative colitis.
Yet, because chronic inflammation can continue for a long time, it's not easy to know its exact impact. "It's a chicken-and-egg scenario," says Dr. Shmerling. "Does chronic inflammation increase the risk of these ailments, or is it a byproduct? It is not always clear."
