What is inflammation and why is it not always bad?
Inflammation is the immune system's response to damage or threat. It is fundamentally protective — the problem is not inflammation itself but inflammation that does not switch off.
Acute inflammation is the version you can see. Injure tissue or introduce an infection and within minutes local blood vessels dilate and become leaky. This produces the four classical signs described in antiquity: redness and heat from increased blood flow, swelling from fluid entering the tissue, and pain from chemical mediators sensitising nerve endings. Each is a side effect of something useful — more blood delivers immune cells, leaky vessels let them exit into tissue, and pain enforces rest on the injured part.
Acute inflammation resolves. Once the threat is cleared, specific signalling actively shuts it down and repair begins. Without it, wounds would not heal and infections would not be controlled.
Chronic inflammation is the harmful version. Here the response persists at a low level for months or years — because the trigger is never cleared, because the resolution signalling fails, or because the immune system is responding to the body's own tissue. Sustained inflammatory activity damages healthy tissue over time, and chronic inflammation is implicated in cardiovascular disease, type 2 diabetes, rheumatoid arthritis, inflammatory bowel disease and others.
Why "anti-inflammatory" claims need care. Suppressing acute inflammation is not automatically good — it is part of healing, and there is ongoing debate about whether routinely blocking it after injury or exercise impairs adaptation and repair. The claim that a particular food is anti-inflammatory is also frequently overstated; established influences on chronic inflammation are overall dietary pattern, physical activity, sleep, smoking, and body fat.
Persistent unexplained inflammation, joint swelling or fatigue warrants medical assessment rather than dietary self-treatment.