The Definitive Guide to Inflammation

Inflammation is your body’s response to infection and injury. When something triggers an inflammatory response, the immune system kicks into gear, isolating the area, removing harmful or damaged tissue, and beginning the healing process. “Inflammation” refers to both the immune processes happening under the surface and the outward signs of an inflammatory response—symptoms like pain, swelling, or fever. 

Inflammation gets a bad rap in the alternative health world: “The root of all chronic illness!” This is true to some extent. Name a disease, and inflammation is involved.  

Crohn’s disease, major depression, heart disease, arthritis—all inflammatory.

Every autoimmune disease—inflammatory, involving an inflammatory response directed at your own tissues.

Even obesity is inflammatory, with fat cells literally secreting inflammatory cytokines.

Yes, but the story is more complicated than that. Inflammation is, after all, a natural process developed through millions of years of evolution. It can’t be wholly negative. Just like our bodies didn’t evolve to manufacture cholesterol to give us heart disease, inflammation isn’t there to give us degenerative diseases. 

The popular refrain that “inflammation is bad” misses the fact that inflammation is necessary and beneficial in certain circumstances and in the right amounts. Where we run into problems is when there is too much for too long, as is so often the case. So how do you know when the line between helpful and harmful has been crossed?

What Causes Inflammation?

In order to understand what causes inflammation, we first need to distinguish between acute inflammation and chronic inflammation:

Acute Vs. Chronic Inflammation

Acute inflammation

Acute inflammation is the body’s relatively brief response (lasting several days or less) to a specific injury or illness. All sorts of things can cause an acute inflammatory response, including 

  • Trauma or injury, whether serious (car accident, stabbing, broken bone) or trivial (paper cut)
  • Infection by bacterial or viral pathogens
  • Burn (including from the sun)
  • Chemical irritant
  • Allergic reaction

When an injury or invasion occurs, the body launches a defense involving the vascular system (veins, arteries, capillaries), immune system, and cells local to the injury. As a result, you’ll likely experience one or more of the five signs that an acute inflammatory response is underway: heat, redness, swelling, pain, or a loss of function. 

Heat, redness, and swelling signal that leukocytes (white blood cells) have arrived to clean up the injury site, mop up pathogens, and oversee the inflammatory process. Pain and immobilization remind you—or force you—to proceed with caution, lest you re-injure the area. Although annoying, these symptoms are only temporary. And they’re a small price to pay. Without acute inflammatory processes, we would quickly succumb to even minor illnesses and injuries.  

But not all acute inflammation is the result of something harmful. Some things that cause acute inflammation are actually good for us. Sun exposure is one example. Exercise is another. Immediately after a single hard workout, inflammatory markers go up because exercise stresses the body—but in a beneficial way. The short-term damage that exercise induces allows us to be stronger, fitter, faster, and healthier in the long term. 

Chronic inflammation

Chronic inflammation is different. The inflammatory response is supposed to be short and to the point, targeting damaged tissues and invading pathogens. Since a big part of inflammation is breaking tissue down before building it back up, the inflammatory response has the potential to harm the body. That’s why it’s normally a tightly regulated system: because we don’t want it getting out of hand and targeting healthy tissue. But if it’s on all the time, regulation becomes a lot harder. 

When inflammation ceases to be an acute response, when it becomes chronic and systemic—a constant low-level feature of your physiology that’s always on and always engaged—big problems arise. Eventually, the body’s general immune response becomes compromised because the system is kept busy tending to the incessant, active inflammation. Long-term effects of chronic inflammation can influence the development of many other conditions from Crohn’s disease to cancer to atherosclerosis to insulin resistance

Besides acute inflammation left unchecked (failure to resolve an infection, for example), chronic inflammation can arise from 

  • Prolonged exposure to an irritant (mold, chemical, allergen)
  • Poor diet (insufficient omega-3 intake, excessive omega-6 intake, sugar-rich, nutrient-poor)
  • Not getting enough sleep or getting only poor quality sleep
  • Chronic exercise patterns
  • Sedentary lifestyle
  • Chronic, prolonged stress (even if low level) 

Gut health also seems to be a major player in chronic inflammation. An inflamed, dysbiotic gut can become permeable, or “leaky,” allowing proteins and pathogens to escape the gut, triggering an immune response.   

You’re probably looking at the list and thinking, gee, I recognize some of my own issues there. If so, you probably have some degree of inflammation lurking under the hood. But how do you know how inflamed you really are?

Inflammation Markers and How to Measure Them

Besides the obvious outward signs, there are certain blood tests and other objective metrics you can use to determine whether you have unfavorable levels of inflammation. 

CRP, or C-Reactive Protein:

Highly sensitive to many different kinds of stressors, CRP rises in response to essentially anything that causes inflammation. This makes it valuable for determining that inflammation is occurring but difficult to determine why that inflammation is occurring—it could be almost anything. 

 “Normal” CRP levels are supposedly 10 mg/L. Absent infection or acute stressors, however, ideal CRP levels are well under 1 mg/L. You want to stay below 1; you don’t want “normal.” Between 10-40 mg/L (and perhaps even 1-9 mg/L, too) indicates systemic inflammation (or pregnancy), while anything above that is associated with real acute stuff. Note that exercise can elevate CRP, so don’t get tested if you’ve worked out in the last couple days.

 IL-6, or Interleukin-6:

T cells (white blood cells that play a huge role in the immune response) and macrophages (cells that engulf and digest—also known as phagocytosing—stray tissue and pathogens) both secrete IL-6 as part of the inflammatory response, so elevated IL-6 can indicate systemic inflammation. 

Heart Rate Variability (HRV):

I’ve written extensively on HRV in the past. Long story short, high HRV predicts lower levels of inflammation.1

CRP and IL-6 are simple blood tests, and HRV is easy to track at home using a number of fitness wearables. This is where I’d start. 

 If you want to get a little more in the weeds, you can look at omega-3s (EPA and DHA). People who have a higher proportion of omega-6 relative to omega-3s will also tend to have higher inflammation. Tests of tissue omega-3 content are hard to find, but they directly measure the omega-3 content of your bodily tissue. Research suggests that omega-3 tissue concentrations of around 60 percent are ideal.2 Alternately, the omega-3 index measures EPA and DHA as a percentage of total fatty acids present in your red blood cells. It doesn’t correlate exactly to tissue amounts, but it’s pretty good. Anything above 8 percent corresponds to a “low risk,” but levels of 12 to 15 percent are ideal. 

Subjective markers of elevated inflammation

You don’t necessarily need blood tests to tell you you’re inflamed, though. Any of the following are signs that your body is dealing with inflammation:

  • Autoimmune flares
  • Water retention
  • Persistent but unexplained nasal congestion
  • Signs of overtraining
  • Unexplained weight gain or retention
  • Chronic aches and pains
  • Fatigue

The problem with these subjective markers, of course, is that they’re nonspecific. Lots of things could cause them. Still, they’re all indicators of a problem that needs to be addressed. 

Systemic inflammatory response syndrome score

Finally, there’s the systemic inflammatory response syndrome, which is incredibly serious and has four criteria.

  • Body temperature less than 96.8 F (36 C) or greater than 100.4 F (38 C).
  • Heart rate above 90 beats per minute.
  • High respiratory rate, 20 breaths per minute or higher.
  • White blood cell count fewer than 4000 cells/mm³ or greater than 12,000 cells/mm³.

If you have two or more of them at once, you qualify—and should probably see a health professional immediately. 

How to Reduce Inflammation

You don’t really need to treat acute inflammation. You can ice a sprained ankle or use a menthol rub to deal with muscle soreness, but my strong inclination is to let acute inflammation run its course unimpeded unless the pain, injury, or illness are severe. Given a bit of time, it will subside as the body heals itself in due course. 

As for mitigating chronic inflammation, I have a post with 10 concrete things you can do to reduce it. Ultimately (and perhaps unsurprisingly), it boils down to doing the things we talk about all the time here: Eat good food. Sleep. Exercise moderately, avoiding chronic patterns, and allow your body time to recover and rest. Do your best to moderate stress. Don’t smoke. Be hot and cold sometimes. 

In short, do your best to avoid stimuli that cause inflammation and support your body’s natural anti-inflammatory processes through a Primal lifestyle. Sticking to the tried and true dietary and lifestyle measures will get you much of the way toward preventing inflammation from becoming chronic and untamed.

About the Author

Mark Sisson is the founder of Mark’s Daily Apple, godfather to the Primal food and lifestyle movement, and the New York Times bestselling author of The Keto Reset Diet. His latest book is Keto for Life, where he discusses how he combines the keto diet with a Primal lifestyle for optimal health and longevity. Mark is the author of numerous other books as well, including The Primal Blueprint, which was credited with turbocharging the growth of the primal/paleo movement back in 2009. After spending three decades researching and educating folks on why food is the key component to achieving and maintaining optimal wellness, Mark launched Primal Kitchen, a real-food company that creates Primal/paleo, keto, and Whole30-friendly kitchen staples.

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