What is Inflammation?

On top of being a crucial component in the body’s response to injury, inflammation is also one of the primary mechanisms through which the body fights off infections.(1) However, while the inflammatory process plays a vital role in maintaining the integrity of the body’s tissues, it can also be detrimental to your health in certain scenarios.  

In contrast to acute inflammation, which is vital to repairing damaged tissues, chronic inflammation can actually impinge on the healing process.(2) You can think of the inflammatory system kind of like a nation’s military force, which is made up of several different components — i.e. there’s the Army, the Navy, the Air Force, and so on.

 If they respond to an event and drop bombs, missiles, napalm, etc., they may eradicate the target, but there is also going to be some damage to the countryside — inflammatory cells can have a similar effect on the body.  In the instance of acute inflammation, there may be some damage done to the countryside (i.e. the body’s tissues) but it’s minimal enough where the body is able to recover. 

Chronic inflammation, on the other hand, is like the military continuing to bombard certain areas of the countryside even though there is no evidence of a threat.  In the context of the body, this continued assault generates hazardous by-products (like cytokines and growth factors) that cause cell death within inflamed tissues, which if gone unchecked, can increase the risk of a number of different inflammatory diseases like obesity, diabetes, and heart disease.(3)(4)(5)

How Does Food Tie Into The Inflammatory Process?

While there are ultimately a number of underlying causes behind chronic inflammation, there is a substantial body of evidence that nutrition plays an important role in the inflammatory process.  Research shows that some types of foods can actually increase baseline levels of inflammation, which over time, can lead to a number of adverse health outcomes — like those mentioned above.(6)

On the flip side, several different kinds of foods have also been found to lower inflammation with regular consumption.  Some studies suggest that certain foods can change your epigenetics — i.e. they can change how certain inflammatory genes behave without actually altering your DNA sequence. 

This, in turn, can lead to positive alterations in the underlying mechanisms behind the inflammatory processes, helping to improve the body’s inflammatory response and reverse chronic inflammation.(7)

Foods That Cause Inflammation

Photo by Christopher Williams

To date, researchers have identified a number of different dietary factors that can increase inflammation.  On top of highly processed foods (like those with refined carbs), those with high concentrations of trans and saturated fats have also been found to have proinflammatory effects.(8)

Refined carbs are sugars — like high fructose corn syrup — or grains that have been stripped of important nutrients like bran and fiber through the processing that they go through.  

They are frequently used in processed foods to enhance flavor and reduce production costs, however, numerous studies have demonstrated their pro-inflammatory effects.

Diets high in things like trans and saturated fats — like those found in red meat and processed foods — have also been shown to raise levels of the C-reactive protein (CRP), a cytokine-derived substance which can impinge on cellular function and ultimately increase the risk of cardiovascular disease.(9)(10)

Additionally, nutrition scientists have also demonstrated that foods with a high glycemic load and glycemic index (particularly foods that have been heat-processed) can also raise levels of inflammation.  An overabundance of glucose in the body can ultimately increase the body production of advanced glycation end products (AGEs), which are a group of oxidant compounds that have been shown to increase inflammation and oxidant stress.(11)(12)

List of Pro-Inflammatory Foods

  • Red meat (beef, bacon, ham, sausage, etc..)
  • Pizza (tomato sauce, fatty cheese, pizza dough)
  • French fries
  • White rice
  • White bread
  • Refined pastas
  • Canned vegetables
  • Sweets (pie, cake, pastries, etc…)
  • Soda/soft drinks
  • Chips, crackers, and other salty snack foods
  • Highly-processed ready-made meals and fast food

Anti-Inflammatory Foods

While researchers have indeed demonstrated that some foods can increase the risk of chronic inflammation, they’ve also identified other dietary factors that may actually reduce inflammation when regularly consumed.    

Most foods that have been shown to have anti-inflammatory effects have tended to contain phytochemicals like carotenoids and polyphenols, which are natural compounds predominantly found in plant-based food sources; however, some animal-derived compounds, like omega-3s, have also been shown to have anti-inflammatory effects as well.(13)

To date, a number of different phytochemicals have been shown to possess anti-inflammatory qualities, helping to modulate inflammatory function through a variety of different mechanisms.(14)

Fruits and Vegetables

Photo by Dose Juice

Countless studies have demonstrated that a diet high in fruits and vegetables can have significant effects on inflammation status, helping to mitigate chronic inflammation and lower the risk of several different inflammatory diseases.(15)

For example, one study published in the American Journal of Clinical Nutrition, which involved almost 500 middle-aged participants, ultimately found that a high dietary intake of fruits and vegetables helped to significantly lower concentrations of the proinflammatory cytokine CRP, which in addition to significantly improving participants’ inflammation statuses, also helped to reduce their risk of metabolic syndrome.(16)

In addition to containing inflammation-modulating phytochemicals, fruits and vegetables are also high in dietary fiber, which research shows may also have anti-inflammatory effects as well, helping to decrease the risk of several inflammatory conditions like obesity, diabetes, and heart disease.(17)

List of Anti-Inflammatory Fruits and Vegetables

  • Berries
  • Cherries
  • Oranges
  • Lemons
  • Grapefruit
  • Grapes
  • Avocados
  • Broccoli 
  • Carrots
  • Tomatoes
  • Mushrooms

Nuts

In addition to fruits and vegetables, tree nuts have also been shown to have anti-inflammatory properties as well.  In addition to containing polyphenols, and fiber, which we’ve already discussed, tree nuts are also high in polyunsaturated fatty acids, which have been shown to modulate inflammation as well.(18)

For example, one 2012 review investigating the effects of several different anti-inflammatory foods ultimately found a significant relationship between regular tree nut consumption and a reduced risk of heart disease, with the researchers ultimately concluding that tree nuts may play an important role in the activation of anti-inflammatory mechanisms within the body.(19)

Omega 3 Foods

Numerous studies have shown that polyunsaturated fats like omega-3s can have significant anti-inflammatory effects.  More specifically, DHA and EPA — two omega 3s which are most popularly found in fish — have been shown to inhibit the expression of pro-inflammatory mediators like ICAM-1 and VCAM-1, helping to improve inflammation status and cellular function.(20)

While omega-3s like DHA and EPA may be most abundant in fish, the can also be found in lower concentrations in some plant-based foods as well, including brussels sprouts, spinach, kale, walnuts, and pumpkin seeds.(21)

Dark Chocolate

While it hasn’t been investigated as thoroughly as most of the other foods on this list, some research does suggest that dark chocolate may possess certain anti-inflammatory properties as well.   

For example, two more recent clinical trials both ultimately demonstrate significant reductions in serum CRP concentration amongst those who regularly consumed dark chocolate, leading the researchers in both studies to conclude that dark chocolate — particularly its flavonoids — may help to mitigate inflammation and improve cardiovascular health in those who regularly consumed it.(22)(23)

Green Tea

There is also some preliminary evidence that green tea may help to reduce inflammation, however, like with dark chocolate, its effects on inflammation have yet to be thoroughly studied in clinical populations. 

While most of the positive findings to date have come from animal studies, a few human-based studies have demonstrated that regularly consuming green tea may indeed help to significantly lower inflammation and reduce the risk of cardiovascular disease.(24)

For example, a few different studies involving human participants did ultimately find that green tea’s catechin content (catechins are a type of flavonoid) had significant effects on the inflammatory process, helping to inhibit the upregulation of several proinflammatory mediators.(25)(26)

What is the Best Anti-Inflammatory Diet?

Photo by freepik

When it comes to the best diet for treating low-grade chronic inflammation, researchers have yet to develop any one standardized dietary approach.(27)

However, the general consensus amongst nutritional scientists is that the optimal anti-inflammatory diet should (1) predominantly involve unprocessed plant-derived foods high in polyunsaturated fats and phytochemicals, and (2) reduce foods with a high glycemic index/load.(28)

In accordance with these basic criteria, researchers have identified a few different standardized diets that appear to have significant anti-inflammatory effects.

Mediterranean Diet

The Mediterranean diet is centrally oriented around healthy unprocessed foods like vegetables, fruits, whole grains, nuts, and fish.  Because it includes many proven anti-inflammatory foods, it’s been well-researched in clinical trials involving inflammation, with most research indeed demonstrating significant effects on inflammation status.  

For example, one 2010 study published in the Proceedings of the Nutrition Society, which involved nearly 800 participants at high risk of cardiovascular disease, ultimately found that a short-term Mediterranean diet intervention significantly improved inflammation status, with those on the Medietran diet on average demonstrating significant improvements in several markers of inflammation, including, serum levels of CRP and IL-6.(29)

Vegetarian Diet

Because it’s centrally oriented around plant-based foods, which make up the majority of foods with known anti-inflammatory effects, the vegetarian diet has also been extensively researched in clinical trials involving chronic inflammation.  To date, there appears to be a substantial body of evidence that regular adherence to a plant-based diet can significantly reduce inflammation.  

For example, one 2019 review ultimately found that compared to individuals on a meat-based diet, those following a strict vegetarian dietary protocol ultimately saw significantly greater improvements in several markers of inflammation, including reductions in serum fibrinogen and total leukocyte concentration.(30)

Another 2017 meta-analysis which included 18 different studies investigating the effects of vegetarianism on inflammation demonstrated that following at least 2 years of adherence, those on the vegetarian diet, on average, experienced significantly greeted reductions in the pro-inflammatory mediator CRP in comparison to those on a non-vegetarian diet.(31)

With that being said, research does suggest that long-term adherence to a vegetarian diet may also increase the likelihood of experiencing several micronutrient deficiencies, which in turn, can impinge on the inflammatory process.  To make a long story short, in order to maximize the anti-inflammatory effects of the vegetarian diet, supplementing with vitamins and minerals like B12, iron, and zinc may be important.   

Wrap Up

Research shows that nutrition plays an important role in the inflammatory process, with some foods being shown to reduce chronic inflammation, while others have been found to increase it.  

Pro-inflammatory dietary factors include red meats and processed foods that contain things like refined carbs and trans/saturated fats, along with foods that have an overall high glycemic load.  

Whole foods, like fruits, vegetables, nuts, and fish, on the other hand, have been shown to positively influence the inflammatory process, helping to decrease blood concentrations of several pro-inflammatory mediators with regular consumption.  

While there is no one standardized anti-inflammatory diet, both the Meditteranean and vegetarian diets have been shown to reduce low-grade chronic inflammation across numerous clinical trials.