Before we begin, it’s crucial to point out that inflammation is normal. It’s the protective and (typically) temporary response of the immune system to pathogens and injury. So while inflammation is a fashionable “buzzword” with negative connotations, this healthy response is not only a good thing. It’s fundamental to optimal human health and function. But it is important to discuss foods that cause inflammation beyond natural levels.

Under normal conditions, inflammation is a self-limiting and controlled process of the immune system.¹ But, when it’s recurrent or poorly regulated, unhealthy levels of inflammation ensue. As do problems.

What are foods that cause inflammation?

Numerous lifestyle and dietary factors contribute to persistent, unhealthy levels of inflammation and disrupt the body’s natural process.²

Let’s take a look at the typical Western-style diet (i.e., Standard American Diet, SAD). This diet is characterized by the overconsumption of heavily processed, refined carbohydrates; simple sugars; low-quality, refined vegetable and seed oils; trans fats; and food products from feedlot animals.³

Here’s how some of these foods that cause inflammation contribute to excessive inflammatory stress in the human body:

6 Foods That Cause Inflammation

Trans Fats

Simply put, there are NO health benefits from the consumption of industrial-produced trans fats. In essence, they’re like tobacco: not beneficial in any amount. This is unfortunate because they’ve become so commonplace in processed “foods.” They’re typically added (in the form of partially hydrogenated vegetable oils) to increase shelf-life and improve mouth feel. Yet nutritionally speaking, trans fats serve NO purpose and they are a major offender as one of the foods that cause inflammation.

In fact, the United States Food and Drug Administration (FDA) recently determined that partially hydrogenated oils are not safe for human consumption.⁴ Fortunately, the FDA will no longer permit the use of partially hydrogenated oils in processed foods.

As good as that news is, it’s important to point out that the FDA also set a compliance period of three years for food companies. So nutrition manufacturers have until June 18, 2018, to remove these oils from their products.

In the meantime, we still need to be vigilant about reading nutrition labels, including both the Nutrition Facts Panel and the ingredients list. In the case of the former, food manufacturers are required to list the amount of trans fats per serving. Having said that, if the amount of trans fat is below 0.5 grams per serving, manufacturers can label the product as containing ZERO. So, if you see “partially hydrogenated vegetable oil” listed in the ingredients, please step away from the health bomb.

The Institute of Medicine (IOM) recommends consumption of trans fats be as low as possible and cites evidence that any intake of industrial-produced trans fats (above zero) will increase one’s risk for cardiovascular disease.⁵

Trans fats are included in the list of foods that cause inflammation due to their association with an unhealthy inflammatory response, endothelial dysfunction (in which the inner lining of blood vessels stops functioning normally), and decreased insulin sensitivity.⁶

Refined Carbohydrates and Sugar

Regular consumption of processed carbohydrates (e.g., refined flours and the “foods” made with them) and added sugars have to be included in any list that highlights foods that cause inflammation.

For starters, various clinical trials have shown that regular consumption of rapidly digesting carbohydrates, which lead to surges into blood glucose, increase inflammatory markers, levels of free radicals, and more. Shifting to a low-glycemic diet with minimally processed carbohydrates (e.g., vegetables, fruits, legumes, minimally processed whole grains), on the other hand, results in improvements in metabolic function and healthy levels of inflammatory markers.²

Further, regular consumption of high-glycemic foods results in high levels of insulin. While insulin is absolutely necessary for metabolic function and has numerous beneficial effects, it also has pro-inflammatory activities. Along these lines, high levels of insulin seem to contribute to unhealthy levels of inflammation.⁷

Additionally, after the surge in blood glucose, consumption of these types of carbs can lead to a rebound effect. That is, an energy crash. The body handles this by initiating a stress response. The corresponding surge of cortisol and catecholamines serves to help stabilize blood glucose levels. This stress response, however, also elicits an inflammatory response and the production of pro-inflammatory chemicals.²

Refined Vegetable/Seed Oils

While saturated fats are commonly regarded as the most inflammatory fats, omega-6 polyunsaturated fats serve as precursors to pro-inflammatory mediators (of the immune system).⁸ Along those lines, overconsumption of omega-6 fats promotes inflammation, particularly when they are consumed in excess of omega-3 fats, which are considered to have an anti-inflammatory effect.²

Speaking of which, experts estimate that throughout human history, the optimal ratio for consumption of omega-6 fatty acids (e.g., linoleic acid) to omega-3 fatty acids (e.g., alpha linolenic acid, DHA, EPA) was about 2:1. With the contemporary diet, this ratio has shifted dramatically in favor of omega-6 fatty acids to 15:1.⁹

Meat, Dairy, and Eggs from Feedlot Animals

It’s not just the vegetable oils found rampant in processed foods contributing to this imbalanced intake of omegas. The consumption of foods from farm animals raised on omega-6 rich oil seeds (e.g., corn, soy) also plays an important role.^10,11

Surely you’ve heard the saying “you are what you eat.” That certainly applies to the animal products we eat, and the nutrition profile of foods such as beef, chicken, dairy, and eggs can be influenced by the type of food on which the animal was raised.

In a recent systematic review, a group of researchers critically analyzed data from 67 different studies comparing the composition of organic (i.e., grass-fed, pasture-raised) and non-organic (i.e., conventional) meat products. They found meat from pasture-raised animals contained 47% more omega-3 fatty acids than conventional meat products.¹²

Meanwhile, a separate review found organic milk significantly higher in omega-3 fats, by an estimated 56%.¹³ Even more importantly, the omega-6 to omega-3 ratio in organic milk was significantly lower, by an estimated 71%.

Further, several studies have examined the nutritional content of eggs from pasture-raised hens compared to eggs from commercial-caged chickens. In another study, eggs from pasture-raised hens were shown to have 2 ½ times more omega-3 fats and less than half the ratio of omega-6 to omega-3 fats.¹⁴

While omega-6 fatty acids are indeed important (essential, in fact), a deficiency is nearly impossible. You’ll get more than enough of these fats when you consume a diet rich in minimally processed, nutrient-dense plant-based foods (e.g., nuts and seeds).

Gluten and Other Food Intolerances

While gluten may not be the devil some make it out to be, the research from Dr. Alessio Fasano, one of the world’s leading researchers and experts in the area of gluten sensitivity, has shown that gluten contributes to intestinal permeability, more commonly known as “leaky gut.” In fact, Dr. Fasano’s work has shown that, after gluten exposure, intestinal permeability may increase in all individuals—not just those with gluten sensitivity.¹⁵

Gluten triggers the body to release a protein called zonulin, which “loosens” the normally “tight” junctions of the cells that line the intestinal tract.¹⁶ This increase in intestinal permeability can lead to undigested proteins entering the bloodstream. This can trigger an immune response from the body that may be associated with a wide range of symptoms—some acute, some chronic and appearing long after the culprit food is ingested.^17,18

This is not to say everyone has to avoid gluten-containing foods or other plant-based foods with similar hard-to-digest proteins (e.g., prolamins, glycoproteins) as found in oatmeal, quinoa, and corn. While gluten is highlighted, the fact is any food intolerance could similarly activate the immune system and be considered one of the foods that cause inflammation.

While not everyone has food sensitivities, there are some likely offenders, including grains (e.g., wheat), soy, dairy, shellfish, FODMAP-containing foods, nightshades, and histamine-containing foods.

As mentioned above, this does not mean everyone needs to avoid these foods. Rather, this is simply meant to raise awareness that a variety of foods—even foods frequently viewed as healthy—may be an issue for some people. While consuming a diet of whole, minimally processed foods is a huge step in the right direction, a more personalized approach may be necessary for some people. That involves identifying and eliminating suspect foods.

Trigger Foods

“Trigger” foods are simply those that lead to overeating. While any food can be a trigger food, most are processed foods that contain added sugar, fat, and salt. This trio of ingredients, provided in precise amounts, are known as the “three pillars of processed foods.”¹⁹ In his book Sugar Salt Fat: How the Food Giants Hooked Us, New York Times Pulitzer Prize-winning investigative journalist Michael Moss discusses how food manufacturers rely on salt, sugar, and fat to “override our dietary self-control” through foods “so perfectly engineered to compel overconsumption.”

Overeating, particularly low-quality processed foods, promotes both acute and sustained inflammatory stress.^20–22 Obviously, the result of regularly overeating is obesity, and inflammatory stress can also result from excess body fat. That’s right. Body fat is much more than an innate storehouse for excess energy. It’s a dynamic tissue that secretes a large number of hormones and chemicals (e.g., pro-inflammatory cytokines), many of which have a pro-inflammatory effect and favor an inflammatory environment.^23–25

While inflammation is a normal, protective response of the immune system, it is designed to be a self-limited, controlled, and temporary process. Unfortunately, there are numerous lifestyle factors that contribute to persistent, unhealthy levels of inflammation and disrupt the body’s natural process to resolve inflammation. Among these factors is diet, and one of the most probable suspects is the typical Western-style diet. But now you understand the key culprits and how to help keep them—and the inflammation they can cause—in check.