What’s a common thread that might connect chronic conditions like cancer, diabetes, heart disease, rheumatoid arthritis, depression, and maybe even Alzheimer’s disease? If you guessed inflammation, you were correct.
The inflammatory response is the body’s natural defensive immune reaction to infection (such as from a cold virus or other foreign invader) or injury (like a cut or twisted ankle). It is, for example, a normal part of tissue healing and regeneration. But when inflammation persists long term—over many months to years—it can damage our cells and organs to the point where disease results. Chronic low-grade inflammation can also cause symptoms such as pain, fatigue, and insomnia, as well as weight gain. Because chronic inflammation is associated with aging, the phenomenon has also been called “inflammaging.”
The search has been on for ways to tame the detrimental side of inflammation. Much of the research has focused not on the pharmacy but the fridge. Certain foods appear to have anti-inflammatory properties. The question is whether eating them can help us avoid illness.
Berries over burgers
The so-called Western diet that many Americans eat is heavy in foods that are considered pro-inflammatory, such as meat, refined carbohydrates (white bread, pasta, baked goods), sugar, and fried and processed foods.
Anti-inflammatory diets, on the other hand, are primarily plant-based. One popular example is the Mediterranean diet, which is composed mainly of vegetables, fruits, legumes, nuts, whole grains, olive oil, and seafood. Studies, including a randomized controlled trial in the Journal of Nutrition in 2016, have linked the Mediterranean diet to lower levels of inflammatory markers in the blood, such as C-reactive protein. Among the many foods specifically called out for having anti-inflammatory effects are berries and cherries, fatty fish like salmon and sardines, and cocoa powder/dark chocolate.
Researchers have attributed the anti-inflammatory benefits of these foods to specific compounds they contain. For example, polyphenols and other protective compounds in fruits, vegetables, and tea block pro-inflammatory chemicals. Omega-3 fatty acids in fatty fish also alter inflammation pathways in the body.
Yet researchers say it’s not the individual foods—and certainly not individual constituents of foods on their own—but rather the combination of healthful compounds in the diet as a whole that is most helpful for fighting inflammation. In other words, simply eating berries for breakfast or pouring olive oil on your steak isn’t likely to radically improve health. Anti-inflammatory foods work synergistically.
Putting anti-inflammatory diets to the test
Researchers are studying the potential benefits of an anti-inflammatory diet for decreasing the risk of or managing a number of conditions, including:
- Cardiovascular disease. Heart disease is the number-one cause of death in the United States. Studies suggest that inflammation plays a key role in the development of heart and blood vessel diseases, known collectively as cardiovascular disease (CVD). One possible reason is that a variety of cells release chemicals called cytokines, which attract the white blood cells that attack and damage blood vessels.
In a 2018 meta-analysis published in the journal Nutrients, researchers used a tool called the Dietary Inflammatory Index (DII) that ranks diets on a scale from most pro-inflammatory to most anti-inflammatory. After reviewing the results of 14 studies examining the link between DII and CVD, the authors noted a 36 percent increased risk of CVD, as well as a higher risk of dying from CVD, in the group with the most pro-inflammatory diet compared to those with the most anti-inflammatory diet.
- Obesity. Meat, fried foods, baked goods, and other foods that are considered pro-inflammatory may promote weight gain because of their calorie density. Adipose (fat tissue) releases cytokines, including interleukin-6 and tumor necrosis factor (TNF), that contribute to and are markers of inflammation. The chemical additives in processed and refined foods like hot dogs, cookies, and white bread can also activate inflammatory pathways and lead to the release of these chemicals. And pro-inflammatory foods and weight gain may both disrupt the diversity of bacteria in the gut’s microbiome—that is, the microorganisms that normally live there. Research is ongoing to better understand the role the microbiome plays in controlling inflammation, as well as in keeping our hunger in check. A less-diverse microbiome has been linked not only to obesity but also to diabetes (see below). Certain components of an anti-inflammatory diet, such as increased fiber intake from fruits, vegetables, and whole grains, may contribute to weight loss directly and also indirectly through greater gut diversity.
- Diabetes. Obesity is one of the biggest risk factors for diabetes, which also has inflammatory roots. A 2022 study in the Archives of Public Health found a higher probability of type 2 diabetes in people who ate the most pro-inflammatory diet (high in red and processed meats, refined grains, and sodas) as measured on the DII compared to those who ate the most anti-inflammatory diet. People who followed a more pro-inflammatory diet also had a much higher body mass index (BMI). Meanwhile, other studies have shown that following an anti-inflammatory diet like the Mediterranean diet is protective against diabetes.
- Cancer. As many as one out of every three cancer deaths are related to diet. A pro-inflammatory eating style might increase cancer risk via its contributions to obesity (which is associated with cancer risk). Another possibility is that the interaction between diet and the environment might alter our genes in ways that increase our cells’ propensity to multiply unchecked.
In particular, studies have been exploring a potential link between pro-inflammatory diets and digestive tract cancers such as colorectal cancer, as well as to cancers of the breast, prostate, lung, and pancreas. An anti-inflammatory diet might have the potential to reduce cancer risk, especially for lung and gastrointestinal tract cancers, although more research is needed.
- Rheumatoid arthritis (RA). In this disease, the immune system misfires and attacks the joints, leaving them inflamed, stiff, and painful. Researchers have proposed various nutritional therapies for RA to potentially tamp down the inflammation—in particular, diets high in omega-3s (as in fish) and low in the omega-6 fatty acid arachidonic acid (AA, which is found in high amounts in animal foods like meat, poultry, and eggs). AA is a precursor to eicosanoids, which are mediators of inflammation. In a 2021 review of 12 studies published in the journal Nutrients, the researchers found that people who followed an anti-inflammatory eating plan such as a Mediterranean, vegetarian, or vegan diet had less pain than those who ate an “ordinary” omnivorous diet—presumably, at least in part, because such diets contain less if any AA and, in the case of the Mediterranean diet, more omega-3s.
- Depression. Depression is more than a state of mind. Chronic inflammation has been linked to this mood disorder, with studies revealing higher levels of cytokines in depressed people compared to those without depression. And some research has suggested that the response to certain antidepressants might differ based on blood levels of the inflammatory marker C-reactive protein. As for a food connection, people who eat a pro-inflammatory diet are more likely to be diagnosed with depression than those who eat an anti-inflammatory diet, according to a 2019 review of studies published in Clinical Nutrition.
BOTTOM LINE: Although the research to date is encouraging, there isn’t enough evidence to confirm that an anti-inflammatory diet prevents chronic disease. That said, many of the foods that have been linked with lower inflammation tend to be healthier overall and may contribute to weight loss. Therefore, they may be worth incorporating into your diet in place of more pro-inflammatory foods. That is, think berries and broccoli over burgers.
There are steps you can take to reduce chronic inflammation. As discussed in the article, one way is to cut back on pro-inflammatory foods (meat, refined grains, and sugary and processed foods) and increase your intake of protective fruits (such as blueberries, cherries, and apples), vegetables (like Brussels sprouts, cauliflower, and spinach), whole grains (which are rich in fiber), nuts, and fatty fish. Here are other ways:
- Lose weight if you’re overweight, especially if you carry your weight in your abdominal area. In a 2018 review of 76 studies, most of them linked weight loss to a reduction in inflammatory cytokines.
- Exercise regularly. Although high-intensity exercise may cause acute inflammation in an untrained body, regular exercise is thought to be protective against chronic disease in part through its anti-inflammatory effects. But don’t overdo it. Overtraining can suppress the immune system and increase infections.
- Don’t smoke, and avoid secondhand smoke when possible. Researchers have found that smokers have higher levels of inflammatory markers in their blood—and that the markers improve when smokers cut back or quit.
- If you drink alcohol, do so in moderation. Though some research has shown that red wine has anti-inflammatory potential (via its polyphenols, namely resveratrol), alcohol itself and its metabolites can promote inflammation in the intestines in various ways, including stimulating bacterial overgrowth, increasing intestinal permeability, and suppressing the gut’s immune defenses.
- Get enough sleep. Insufficient sleep has been linked to increased inflammatory markers, which may help explain why people who sleep poorly are at increased risk for some chronic medical conditions like diabetes and heart disease. A 2020 study, which tracked the sleep habits of more than 500 people for a week, found that even inconsistent sleep may increase inflammation, especially in women.
- Learn ways to deal with stress and anxiety. The body’s “fight-or-flight response” triggers the release of adrenaline and the stress hormone cortisol to deal with a real and immediate threat. But if that response is ongoing, as a result of chronic stress or anxiety, it can lead to chronically elevated hormone levels and chronic inflammation. In fact, it’s now thought that chronic inflammation may be what links stress to chronic illness. Meditation and yoga are two practices that have been shown to reduce inflammatory markers, including cortisol.