Derek Burnett
Derek Burnett is a Contributing Writer at Bottom Line Personal, where he writes frequently on health and wellness. He is also a contributing editor with Reader’s Digest magazine.
Chronic inflammation has gotten a lot of press in recent years, as researchers establish associations between it and numerous health problems, including diabetes, Alzheimer’s, depression, and even some cancers. Arguably the topic receiving the most attention is the potential link between inflammation and heart disease. But is there an actual causal connection between the two conditions? What does the science really tell us about the relationship between inflammation and heart disease?
You may already know that there are two main types of inflammation. Acute inflammation occurs at the site of an injury or infection, as the immune system rushes to neutralize a threat, protect surrounding tissues, and clear away debris from dead or damaged cells. The swelling and redness that occur when you twist your ankle or get hit with a baseball are examples of acute inflammation, as is the congestion and runny nose when you contract the common cold. Once the wound is healed or the infection conquered, the many immune-system cells and substances that have been deployed recede and the body goes back to normal. And that’s a good thing, since those same substances that promote healing can be damaging to surrounding healthy tissue.
But chronic inflammation is a different beast. Although it involves many of the same biochemical processes, the difference is that it is ongoing. Whatever triggered the immune system…whether a legitimate threat or not…remains in place, so the body can spend weeks, months, years, even decades, with inflammatory substances circulating at a low level through the bloodstream. Over time, as the inflammation theory of disease goes, these substances do harm to tissues throughout the body, whether in the brain, the eyes, the liver, the lungs, or elsewhere. Tissues and organs exposed to inflammation for long enough begin to change. These structural changes may constitute disease unto itself, or they may essentially pave the way for diseases to take root. And sometimes, inflammation begets inflammation as damaged tissue signals distress to the immune system, creating a cycle of damage.
A hallmark of cardiovascular disease is a condition called atherosclerosis, in which the interior surfaces of the blood vessels become lined with fatty plaques, thickening and hardening the organs’ walls. Those plaques consist of LDL cholesterol, cellular waste products, calcium, blood cells, and other fatty substances. Once a plaque forms on an artery wall, it can accumulate more of these and other substances, narrowing the space through which the blood flows. This causes an increase in blood pressure and forces the heart to work harder to move the same amount of oxygen-carrying blood to the tissues throughout the body. Sometimes a plaque becomes so large that the blood vessel is blocked. When that happens to a vessel feeding the heart, the result is death of a section of the heart’s tissue, also known as a heart attack. Plaques may also burst, sending a cluster of debris that forms a blood clot. When a clot blocks the flow of blood to the brain, an ischemic stroke occurs.
Over the past few decades, researchers have refined our understanding of the processes outlined above. Today, it’s widely believed that inflammation plays an important role both in how plaques first appear and how they cause damage. In fact, many doctors are comfortable today referring to atherosclerosis as an inflammatory disease.
There is certainly mounting evidence linking the two conditions. We know, for example, that people with autoimmune disorders have an elevated risk of developing cardiovascular disease and that it tends to affect them up to a decade earlier than the rest of the population. Animal models show that plaques are less likely to develop when inflammatory cell types are removed, and in human studies atherosclerosis is linked with higher levels of inflammation biomarkers. It’s also been demonstrated that medications to reduce inflammation have a positive effect on atherosclerosis.
The mechanisms by which chronic, low-level inflammation contributes to heart disease are incredibly complex. But its broadest outlines can be fairly simply understood by adding inflammation into our earlier discussion of atherosclerosis. When the body is subjected to years of chronic inflammation from a poor diet, smoking, pollution, substance abuse, stress, or other factors, the inflammatory cells circulating in the bloodstream begin to cause changes to the structures of the blood vessels. To use an oversimplified analogy, artery walls that were once smooth roadways become filled with cracks, potholes, frost heaves, and other irregularities. Thanks to these disruptions of the vessels’ surfaces, fatty substances that might have passed freely along them now get hung up and begin to accumulate. In that sense, the buildup of plaque is no longer understood as a purely mechanical fact of waxy substances collecting on the artery wall, but rather as a downstream effect of immunity-related biochemical reactions.
But the story doesn’t end there. The immune system sees the deposited plaques as a threat and deploys yet more inflammation to the site to contain the damage. New immune-system fighters flood the zone, walling off the plaque by building a protective layer around it. Thanks to that added immune activity, the plaque has now increased in size, blocking more blood flow than before. That buildup may become unstable and rupture, forming a thrombus or clot that may travel on through the bloodstream and cause a stroke or heart attack when it blocks the brain or heart.
Fortunately, the addition of inflammation to our picture of heart disease doesn’t really introduce any complications when it comes to protecting oneself from atherosclerosis. That’s because the very same factors that stave off inflammation are the ones that we’ve always known protect against heart disease. By refraining from smoking, drinking only in moderation, eating a plant-based diet, exercising, getting enough sleep, and reducing stress, you can protect yourself not just from heart disease but from other diseases and conditions related to inflammation.
