When you cut or bruise yourself, you may notice that the area around the injury becomes red, hot or painful within a very short period of time – within minutes or seconds. This is inflammation, the immune system’s first line of defence against external threats, and it is vital for our survival. However, this process can and does turn against us, and is an important component of the ageing process. How does something that evolved to protect us ultimately help to kill us, and what can we do about it?
Inflammation is triggered by damage and by molecules associated with pathogens (such as lipopolysaccharide, which is found in the cell walls of some bacteria). When inflammation is triggered, white blood cells called neutrophils and macrophages are recruited to fight whatever pathogen might have entered the body. Signalling molecules released during inflammation also have various effects such as increasing blood flow to the site of infection (the cause of redness), increasing the permeability of the blood vessels (swelling), and activating specialised T and B cells.
Inflammation is important because it allows the immune system to respond very rapidly to an infection. Unlike T cells and B cells, which specifically target a single type of pathogen, neutrophils and macrophages are capable of killing any pathogen. This means that it doesn’t take over a week to mount a respond to an infection by a new pathogen, by which point you would probably be dead. The downside is that inflammation causes a lot of collateral damage, which has to be repaired once the infection is resolved. This is an acceptable price to pay in most situations. However, inflammation can become a problem, particularly if it occurs when it shouldn’t.
Inflammation isn’t an entirely all or nothing process – small quantities of inflammatory molecules can be found in the blood of healthy individuals. This is because inflammation can be caused by any form of damage, not just damage caused by pathogens. Our cells suffer constant damage as a result of normal metabolic reactions, leading to the production of a small quantity of inflammatory molecules that enter the circulation, but not really enough to cause meaningful damage. When a food or product is advertised as ‘reducing inflammation’, this background inflammation is usually what they are referring to.
Unfortunately, as we age, sources of background inflammation increase. Metabolic reactions become inefficient and cause more damage. ‘Zombie’ senescent cells and the build-up of ‘junk’ molecules also contribute to the production of inflammatory molecules. If you want to read more about these processes, you should read this article. The result of this is that ageing is accompanied by increasing background levels of chronic inflammation. This increase has been termed ‘inflammageing’.
Inflammageing is a bad thing because inflammation is involved in driving pretty much every age- related disease. In atherosclerosis, fatty lesion growth is driven by macrophages attacking oxidised cholesterol. Inflammation increases the risk of cancer and helps tumours to grow and spread, damages the brain in Alzheimer’s disease, contributes to insulin resistance in type II diabetes, and may contribute to increased risk of death from COVID-19.
Thankfully, there are multiple ways of reducing the production of inflammatory molecules. What follows are some of the most effective and actionable steps you can take: