Recently by Mark Sisson: What a Difference a Few Months Can Make
Inflammation is one of those words that people use without really thinking about its actual meaning. So today we’re going to take a bit of a break from the blood lipid series to cover inflammation. In later posts, I’ll dig deeper into how the inflammatory response works with stuff like exercise and heart disease, but for now, I’ll just get the basics out there.
Existence is suffering, according to certain schools of thought. I don’t know that I’d go quite that far, but I would emphatically state that anyone who spends a modicum of sentient time in the space time continuum we call existence is gonna experience some unpleasantness. A bump on the knee, a bacterial infection, an acute injury, a persistent illness, a death of a loved one, a broken heart. It’s a big and often angry world that doesn’t necessarily care about you, and something’s gotta give. When that happens and the sanctity of our bodies is interrupted by pain, injury, or illness, our bodies respond with inflammation.
There’s that word again: inflammation. It pops up quite often in our circles, usually playing either the starring role, absolutely killing it as a supporting actor, or stealing the show with a cameo appearance in some malady or another. Heart disease, obesity, depression, arthritis (and any -itis, really), autoimmune diseases, insulin resistance — all classics worthy of accolades (although tonsillitis totally got robbed in last years Oscars), and all linked to inflammation, sometimes even causally. So inflammation must be terrible, right? It must be completely and unequivocally a negative trait, kinda like how our body evolved to manufacture cholesterol to kill us. What, didn’t you know that coronary heart disease confers a survival advantage?
Jokes aside, the fact that inflammation is a common, natural, innate response to injury/pain/illness/stress is a hint that there’s probably something necessary about it. It’s not some accident, nor is it our body hell-bent on making life miserable for itself. On the contrary: inflammation is our body’s way of saying it isn’t gonna take the affront of injury or illness lying down. It’s not a passive spectator totally reliant on the kindness of Pfizer and Walgreens and an ice pack to get it out of a jam. Although you wouldn’t think it, what with the barrage of altruistic allknowing medical experts and commercials both touting some essential pharmaceutical, our bodies can actually heal themselves. And the first responder, so to speak, is the inflammatory process. That’s right. Pain, swelling, redness, and that radiating sense of warmth that we feel at the site of an injury or illness don’t manifest by accident or for kicks. That’s inflammation, and it’s essential to our very existence in a world of hurt.
First up, acute inflammation.
The initial response to a pathogen or an injury is acutely inflammatory. In other words, it is brief, lasting several days or less. All sorts of things can cause an acute inflammatory response. Here are a few:
- Trauma (punch, kick, golfball to the head)
- Infection by pathogens (bacterial, viral)
- Burn (sun, fire, seatbelt buckle on a summer day)
- Chemical irritants
- Allergic reaction
Things happen pretty fast in an acute inflammatory response and involve several different players, including the vascular system (veins, arteries, capillaries and such), the immune system, and the cells local to the injury. First, something painful and unpleasant happens; choose one of the above injury options. Then, pattern recognition receptors (PRR) located at the injury site initiate the release of various inflammatory mediators, which in turn initiate vasodilation (or widening of the blood vessels). This allows increased blood flow to the injury site, which warms the site, turns it the familiar red, and carries plasma and leukocytes to the site of the injured tissue. The blood vessels become more permeable, thus allowing the plasma and leukocytes to flow through the vessel walls and into the injured tissue to do their work. Emigration of plasma into tissue also means fluid buildup, which means swelling. At the same time, the body releases an inflammatory mediator called bradykinin which increases pain sensitivity at the site and discourages usage of the injured area. These sensations — heat, redness, swelling, pain, and a loss of function — are annoying and familiar, but they are absolutely necessary for proper healing.
Allow me to explain why the four primary symptoms of acute inflammation are important:
- Increased blood flow warms the injury and turns it red, which can be irritating and unsightly, but it also carries the guys — leukocytes — that will be cleaning up the injury site, mopping up pathogens, and overseeing the inflammatory process.
- Swollen body parts don’t fit into gloves, are really sensitive, and don’t work as well as their slim counterparts, but a swollen finger is a finger that’s full of a plasma and leukocyte slurry and therefore on the road to recovery.
- Pain hurts, but if an injury doesn’t hurt and it’s serious, you’ll keep damaging it because you won’t know not to use it.
- Loss of function prevents you from using what could be one of your favorite body parts, but you don’t want to make it worse be re-injuring it. Besides, it’s only temporary.
These symptoms both indicate and enable inflammation (and, thus, healing), but what’s the deal with inflammation being linked with all those chronic illnesses — like obesity, heart disease, and depression? How does something normal and helpful go haywire and become implicated in some of the most crushing, tragic diseases of our time?