How Diet Affects Inflammation and Chronic Pain

We hear about inflammation a lot these days in terms of the role it plays in many chronic disease conditions, including cancer, type II diabetes, and heart disease. Inflammation can play a large role in chronic pain as well, especially when it comes to painful autoimmune conditions like rheumatoid arthritis, fibromyalgia, multiple sclerosis, and ankylosing spondylitis. Inflammation also contributes to osteoarthritis, a painful condition which affects more than 500 million people globally.

If inflammation is contributing to your pain, one of the easiest ways to reduce inflammation is through diet. You can make changes to your diet immediately, and start experiencing a reduction in inflammation within a few days.

Eating an anti-inflammatory diet is so important for people with chronic pain that researchers have made a food pyramid for chronic pain!

In this article, I’ll start with a quick lesson on localized versus systemic inflammation, and how both can contribute to pain. Then I’ll discuss the major food groups that cause inflammation: processed foods, grains, dairy, and processed and factory-farmed animal products. I’ll also discuss the trendy carnivore diet, and finally I’ll answer the question: What is the least inflammatory diet for humans?

How Localized and Systemic Inflammation Cause Pain

Localized inflammation is the type that I typically talk about in the context of Clinical Somatics. Localized inflammation occurs at the site of an injury or infection. When cells of your body are damaged or attacked, your immune system kicks in to remove the harmful stimuli and begin the healing process. Blood vessels dilate and capillaries become permeable; the increased blood flow to the affected area makes it swollen, red, and warm. The swelling can press on nerves and cause pain. Another cause of pain is the release of inflammatory mediators; these substances activate nociceptors (pain receptors) and contribute to the pain you feel in localized inflammation.

When localized inflammation is acute (lasting for a short period of time), it’s beneficial because it facilitates the healing process. However, when localized inflammation becomes chronic—like in a joint that is constantly being subjected to too much strain and pressure—the physical wear-and-tear and the never-ending immune system attack will gradually destroy protective joint tissues and cause dysfunction and deformity of the joint.

If you feel pain and symptoms of inflammation in just one specific part of your body, then chronic, localized inflammation is typically the type of inflammation involved. In order to reduce or eliminate this type of inflammation, you must release your chronic muscle tension and change the habitual posture and movement patterns that are causing the damage to your body.

However, if you feel inflammatory pain in multiple areas of your body, systemic inflammation is likely involved. Systemic inflammation occurs when your immune system produces the inflammatory response throughout your body rather than in just one specific area. When systemic inflammation is chronic, research shows that it can cause pain, autoimmune conditions, destruction and scarring of tissues, buildup of plaques in arteries, changes in gene expression, cancer, type II diabetes, dementia, depression, and other dangerous conditions.

Some proven causes of systemic inflammation are viral and bacterial infections, allergies, smoking, obesity, stress, and alcohol intake. And another major cause of systemic inflammation is the food we eat. Inflammation resulting from diet affects the vast majority of people in the world to some degree, whether they’re aware of it or not.

Why Processed Foods Cause Inflammation

All processed foods can cause inflammation, for a number of reasons:

  • Processed foods contain non-nutritive additives and chemicals such as flavorings, emulsifiers, sweeteners, and preservatives.
  • They are often high in sugar, saturated fat, and trans fat, while being low in protein and fiber.
  • They can alter the balance of gut bacteria, which has a direct effect on the level of inflammation throughout our body.
  • They are nutritionally unbalanced due to removal of micronutrients (vitamins, minerals, and phytochemicals) during processing.
  • Packaging can also contribute to the chemicals present in processed foods.

Processed food is so unlike whole food that researchers theorize that the body may see processed food as a foreign substance, triggering an inflammatory response referred to as “fast food fever.” Research shows that the negative effects of processed food cannot be reversed by ensuring proper nutrition, so there are clearly some qualities of processed food other than low nutritional value that are damaging to the human body.

Food additives, like emulsifiers, thickeners, artificial flavors, and preservatives, are added to processed foods to make them last a long time on the shelf, taste good, and even be addictive. These additives can alter the balance of our gut bacteria, leading to inflammation in the gut and throughout the body. Food additives are linked to inflammatory conditions, including autoimmune diseases and cancer.

The Arthritis Foundation cites mono-sodium glutamate (MSG) as one of eight food ingredients most likely to cause inflammation, making osteoarthritis symptoms worse. MSG can be present in fast food, chips and snack foods, soups and soup mixes, deli meats, frozen meals, condiments, and more. The Arthritis Foundation reports that MSG can affect liver health and trigger two pathways of chronic inflammation.

Trans fat is created when food manufacturers add hydrogen to vegetable oil; this makes the oil solid at room temperature and extends its shelf life. Trans fat has been proven to trigger systemic inflammation, contributing to chronic inflammatory conditions. You should avoid foods with “hydrogenated” and “partially hydrogenated” oils on the label. Ideally, you should avoid trans fat completely. You’ll find trans fat in fast food, margarine, commercial baked goods, and processed snack foods.

Omega-6 and omega-3 fatty acids are essential fatty acids, meaning that they are necessary for physiological functioning but cannot be produced by the body. Humans evolved consuming a roughly equal amount of omega-6s and omega-3s. However, the modern Western diet has ratio of approximately 20 omega-6s to one omega-3.

This excess of omega-6 fatty acids and deficiency of omega-3s increases inflammation and the risk of autoimmune diseases and cancer. Omega-6 fatty acids are found in many oils used in processed food (like corn, vegetable, safflower, sunflower, grapeseed, peanut, and soy). Fried food, salad dressings, and mayonnaise are major sources of omega-6s in the Western diet, and should be limited.

As humans evolved, we ate zero added sugar and very little free sugar (only in the form of honey, when we could find it). The fruits we ate were generally much lower in sugar than the fruits we eat today, which have been selectively bred to have more sugar. The short-term effect of sugar on the body is to raise blood sugar and insulin levels, which increases fat gain and fat retention. Excess body fat increases inflammation, as fat cells release inflammatory substances like leptin and cytokines.

But the inflammatory effects of sugar go beyond just body fat. People who consume diets that are higher in sugar have more inflammatory markers in their blood, including C-reactive protein (CRP). CRP is produced by the liver, and CRP levels rise when inflammation is occurring in the body. When people reduce their sugar intake, their inflammatory markers are reduced.

Research has clearly demonstrated that dietary sugar is a key factor in developing chronic inflammation, neuroinflammation, and painful autoimmune conditions including rheumatoid arthritis and multiple sclerosis. Sugar can increase levels of LDL cholesterol, which increases inflammation and CRP levels. Sugar also stimulates production of free fatty acids in the liver, which then triggers inflammatory processes.

Approximately 75% of packaged foods contain some form of added sugar. There are 60 or more names for added sugar used on food ingredient labels, so be wary and be sure to look at the grams of added sugar per serving.

Refined carbohydrates, which include bread, crackers, white rice, and cereals, have essentially the same effect on our metabolism as pure sugar. While dietary advice in the 1980s and 90s told us to avoid fat and consume carbohydrates at will, researchers now realize that fat was not the culprit they were looking for. Instead, it was refined carbohydrates, which trigger insulin production and stimulate inflammation.

So, it’s important to limit your intake of both sugar and refined carbohydrates. Instead, choose whole-food sources of carbohydrates, like vegetables, fruit, potatoes, sweet potatoes, legumes, nuts, and seeds. If you consume grains, be sure to do so in their whole, unprocessed form—not whole grains that have been processed into whole-grain bread, pasta, crackers, etc.

Why Grains Cause Inflammation

Grains, along with other plant foods, contain lectins. Lectins are proteins that plants produce as a self-defense mechanism, so that predators like us won’t eat them. In our digestive system, lectins can prevent absorption of nutrients, damage the walls of our intestines, and contribute to painful autoimmune conditions.

Gluten is the most problematic lectin because we are over-exposed to it. In addition to being present in all wheat products, which make up a large portion of the western diet, gluten is added to many processed foods, beauty products, medications, and supplements. While statistics vary, some studies suggest that up to 30% of the population is now gluten sensitive, and somewhere between 50-99% of people with celiac disease or gluten sensitivity are never diagnosed.

When gluten reaches our gut, it’s broken down into the proteins gliadin and glutenin. In people who are gluten sensitive or who have celiac disease, the immune system sees gliadin as dangerous and produces antibodies to attack it. Gliadin also increases the release of zonulin, a protein that modulates the permeability of junctions between cells of the intestinal walls. Increased presence of zonulin causes intestinal permeability (leaky gut), which allows toxins, microbes, food particles, and the anti-gliadin antibodies to leak out of the intestines and travel through the body.

Anti-gliadin antibodies often attack other things in the body besides just gliadin, and can trigger the immune system to attack its own tissues; this is how autoimmune conditions result from gluten sensitivity and celiac disease. Gluten sensitivity is associated with many painful inflammatory and autoimmune conditions including rheumatoid arthritis, fibromyalgia, multiple sclerosis, ankylosing spondylitis, and migraine headaches. Research shows that when gluten is taken out of the diet, pain and other inflammatory symptoms of these conditions improve.

Some people with gluten sensitivity may be sensitive to all lectins, so it can be helpful to do an elimination diet for a period of time in which they eliminate all grain products. While grains are not the only food source of lectins—legumes are another major source—they tend to be the most prevalent and problematic source in the western diet. In addition, since lectins bind to carbohydrates in the body, reducing carbohydrate intake may help to reduce the negative effects of lectins.

Why Cow Diary Products Cause Inflammation

Like gluten, research consistently shows that dairy consumption leads to to an increase in inflammatory symptoms. Dairy consumption has been linked to a number of autoimmune conditions, including rheumatoid arthritis, multiple sclerosis, ankylosing spondylitis, type 1 diabetes, inflammatory bowel disease, thyroid disorders, and others. Dairy consumption is also linked to other inflammatory conditions, such as osteoarthritis and Parkinson’s disease.

There are several reasons why cow dairy products cause inflammation when consumed by humans. The first is lactose, a naturally occurring sugar in dairy products. Approximately 68% of the world’s population is lactose intolerant.

People who are lactose intolerant don’t produce lactase, the enzyme necessary for breaking down lactose. Undigested lactose becomes fermented in the gut, producing gas and leading to symptoms including bloating, nausea, vomiting, diarrhea, or constipation. If you are lactose intolerant, continued consumption of dairy can cause damage to the gut lining, a condition known as intestinal permeability or “leaky gut.” As discussed in the previous section, intestinal permeability leads to inflammatory reactions associated with painful autoimmune conditions.

The second reason why dairy leads to inflammation is the proteins found in cow’s milk, casein and whey. Casein in particular is difficult for many people to digest, and often leads to an inflammatory autoimmune response. However, there are two types of casein found in dairy, A1 and A2, which have slightly different chemical structures.

A1 casein appears to be the trigger for autoimmune reactions, while A2 is much less problematic. A1 casein can act like a lectin in the body. Due to a process known as “molecular mimicry,” A1 casein molecules can be mistaken for lectins (such as gluten) by the body, and the immune system can respond in the same way—with inflammation.

Unfortunately, most American dairy products come from cows that produce A1 casein. Some dairy products from alternative sources such as goats, sheep, buffalo, and specific breeds of cows contain predominantly A2 proteins. These can be much easier to digest and less likely to cause painful inflammatory symptoms.

In addition to naturally occurring lactose, casein, and whey, synthetic substances are given to cows during the dairy production process and are present in the milk they produce. These include hormones to increase milk production and antibiotics to prevent infection. Pesticides, heavy metals, and other toxins are also present in cow’s milk, likely due to being consumed in animal feed. All of these synthetic, toxic substances are known to contribute to inflammation and chronic disease in humans.

Why Processed and Factory-Farmed Animal Products Cause Inflammation

When it comes to consuming animal products, quality is of utmost importance. Processed meat and factory-farmed animal products are low-quality and increase inflammation, while unprocessed, pasture-raised, grass-fed animal products can be part of an anti-inflammatory diet.

All processed foods contribute to inflammation, as discussed earlier in this article. When it comes to processed meat in particular, the curing and preserving process includes dangerous additives like sodium phosphate and sodium nitrite. Additives like these are so bad for human health that in 2015 the World Health Organization classified processed meats as a “class 1 carcinogen.” This means that research has proven conclusively that processed meats contribute to cancer, a highly inflammatory condition. If you are going to eat processed meat, be sure to choose those that are labeled “uncured,” and read the list of ingredients.

Factory-farmed animal products are inflammatory as well, especially when consumed in excess. The main reason why factory-farmed animal products cause inflammation is due to the animals’ unnatural diet: grains. In contrast, pasture-raised animals eat grass, nuts, and seeds, which are high in alpha-linolenic acid, an essential omega-3 fatty acid.

Grain-fed animals result in meat and eggs with an unnatural ratio of omega-6 to omega-3 fatty acids. Humans evolved eating a diet with a roughly equal (1:1) ratio of omega-6s to omega-3s. Sadly, the typical Western diet is around 20:1 or higher. This excess of omega-6 fatty acids and deficiency of omega-3s increases inflammation and the risk of autoimmune diseases and cancer.

The omega-6:3 ratio for grass-fed beef is approximately 2:1, while the ratio for grain-feed beef is approximately 9:1. It’s important to note that all types of grain-fed meat, including pork, chicken, turkey, and lamb, have similar omega imbalances.

Eggs from pasture-raised hens have three times the omega-3s than conventionally raised eggs, resulting in a favorable 2:1 ratio of omega-6:3. Pasture-raised meat and eggs also contain more antioxidants, micronutrients, and trace minerals than conventionally raised meat and eggs.

Conventionally raised animal products also contain toxic substances that can increase inflammation and weaken our immune system. These include antibiotics to prevent disease, hormones to increase animal growth, and pesticides, which are present in animal feed.

When shopping for unprocessed animal products, the labels to look for are “pasture-raised” and “grass-fed.” Other labels that sound healthy, like “cage-free” and “free range,” do not mean that the animals ate grass. You should also look for the label “organic,” which means that the animals ate organic (pesticide-free) feed, and were not given hormones or unnecessary antibiotics.

What About the Carnivore Diet?

So, we just learned that processed and factory-farmed meats increase inflammation, especially when consumed regularly. But what about the trendy carnivore diet? This diet has become mainstream lately for two reasons: it can be very effective for weight loss, and it removes all potential allergens from the diet.

The carnivore diet can allow for weight loss because it doesn’t include any carbohydrates, which elevate insulin levels and tell the body to store fat. Simply having excess weight on the body increases inflammation, as fat cells release inflammatory molecules like leptin and cytokines. So, losing weight reduces inflammation. If you decide to use the carnivore as a short-term means to lose weight, quality is key. You should consume meat and eggs from pasture-raised animals only, preferably those who have consumed organic feed and are antibiotic- and hormone-free.

The carnivore diet can also be very beneficial for people who suffer from autoimmune and other inflammatory conditions. Even though plant foods are very healthful due to their nutrients, antioxidants, and fiber, certain plant foods can cause inflammation in some people.

For this reason, some people with painful inflammatory conditions report feeling great when they adopt a diet in which they eat predominantly whole, unprocessed animal products. This is because they’ve eliminated the plant foods that could be triggering their inflammation. Also, this type of diet reduces or eliminates processed food and added sugar.

The danger in following a carnivore diet long-term is the vast reduction of fiber intake. Research clearly shows that our gut microbiota needs a large amount of fiber from diverse plant sources in order to be most healthy and keep our immune system strong. So, a carnivore diet could be used short-term as a type of elimination diet, but it is likely not the most healthful long-term solution for most people.

I want to reiterate the fact that if you decide to do a carnivore diet, the quality of the animal products you consume is of utmost importance. You should consume meat and eggs from pasture-raised animals only, preferably those who have consumed organic feed and are antibiotic- and hormone-free.

What Is the Least Inflammatory Diet for Humans?

The least inflammatory diet for humans is one that is as close as possible to what we ate as we evolved. In general, inflammation results from consuming or being exposed to substances or stressors that humans are not adapted to. The more we can adopt a diet and lifestyle that is similar to that of our hunter-gatherer ancestors, the less inflammation we’ll have.

This means eating a diet based on whole, unprocessed foods that were able to be hunted or gathered: meat, fish, eggs, vegetables, fruits, nuts, and seeds. This whole-food “primal” diet does not include foods that became widely available as a result of farming, like grains and dairy. And of course, it does not include processed foods or added sugar.

Research on the effect of diet on various inflammatory chronic pain conditions is so abundant that scientists have created a food pyramid for chronic pain. The pyramid is new and will hopefully be refined as time goes on, but it’s a step in the right direction. And it should be noted that we all have different dietary triggers of inflammation, so each person needs to explore their own diet and find out which foods are inflammatory for them.

The best way to do this is with an elimination diet like the Whole30 diet. The Whole30 diet removes all potentially inflammatory foods from your diet for 30 days. Then, you’ll reintroduce certain types of foods one at a time so you can see how each inflammatory food (like sugar, gluten, dairy, etc.) affects you. This is done in a systematic way, returning to a complete elimination diet for several days in between each food reintroduction.

While it may be tough, this type of elimination diet is essential in figuring out which foods trigger inflammation for you. Modifying your diet is the simplest way to reduce inflammation. Once you get used to it, you may find that you feel so good on this diet that you’ll just keep eating “primally” all the time!