Inflammation: Causes, Symptoms & Anti-Inflammatory Diet
Inflammation is the body's response to injury. It works to heal wounds, but it can also play a role in some chronic diseases.
Credit: Melodia plus photos | Shutterstock

Inflammation is a vital part of the body's immune response. It is the body's attempt to heal itself after an injury; defend itself against foreign invaders, such as viruses and bacteria; and repair damaged tissue. 

Without inflammation, wounds would fester and infections could become deadly. Inflammation can also be problematic, though, and it plays a role in some chronic diseases. 

Inflammation is often characterized by redness, swelling, warmth, and sometimes pain and some immobility. When you stub your toe, for example, biochemical processes release proteins called cytokines as "emergency signals" that bring in your body's immune cells, hormones and nutrients to fix the problem, according to Dr. Scott Walker, a family practice physician at Gunnison Valley Hospital in Utah. 

Arteries dilate, blood flow increases, and capillaries become more permeable so that white blood cells, hormones and nutrients can move into the spaces between cells. White blood cells swarm the injured area and ingest germs, dead or damaged cells and other foreign materials to help heal the body, Walker said. Hormones called prostaglandins create blood clots to try to heal the damaged tissue and remove them when healing is finished; they also trigger pain and fever as part of the healing process. 

Swelling happens because fluid accompanies the white blood cells, hormones and nutrients. “[The fluid] diffuses into the area and causes the swelling that can cause increased pressure [to nerve endings] and pain,” Walker said. Pus is an accumulation of white blood cells that have died after ingesting the threatening materials and the way the body expels those no-longer-needed cells. 

There are two types of inflammation: acute and chronic (sometimes called systemic) inflammation. Acute inflammation arises after a cut or scrape in the skin, an infected ingrown nail, a sprained ankle, acute bronchitis, a sore throat, tonsillitis or appendicitis. It is short-term and the effects subside after a few days.

Chronic inflammation is long-term and occurs in “wear and tear” conditions, including osteoarthritis, and autoimmune diseases, such as lupus and rheumatoid arthritis, allergies, asthma, inflammatory bowel disease and Crohn’s disease, Walker said. Habitual or environmental factors, such as excess weight, poor diet, lack of exercise, stress, smoking, pollution, poor oral health and excessive alcohol consumption can also lead to chronic inflammation.

Often, acute inflammation is perceived as "good," because it is the body’s attempt to heal itself after an injury, and chronic inflammation as "bad" but Walker said that is not a very useful distinction. Whether acute or chronic, inflammation “is the body’s natural response to a problem, so it makes us aware of issues that we might not otherwise acknowledge,” he said. 

Chronic inflammation, sometimes called persistent, low-grade inflammation, happens when the body sends an inflammatory response to a perceived internal threat that does not require an inflammatory response. The white blood cells swarm, but have nothing to do and nowhere to go, and they sometimes eventually start attacking internal organs or other necessary tissues and cells, Walker said. 

Other times, the threat is real but we do not feel it or the inflammatory response, and the inflammation can persist forever. Persistent inflammation has been linked to a variety of ailments, including heart disease. It is often associated with environmental or habitual factors, such as pollution or poor diet, which has made it of interest to nutritionists. 

When health experts speak of an “anti-inflammatory diet,” this kind of low-grade, chronic inflammation is what they typically hope to help. An anti-inflammatory diet may also be helpful for those suffering from arthritis, according to the Arthritis Foundation

Chronic, low-grade inflammation often does not have symptoms, but doctors can test for C-reactive protein levels (CRP), which increase when the body is inflamed. These tests are usually done when doctors are trying to figure out if a patient has a disease like lupus, arthritis or heart disease, according to the Mayo Clinic.

Scientists are still working to understand all the implications of chronic inflammation on the body’s health, but it is clear that it affects the body in myriad ways. Some of them may be:

Heart disease

Chronic inflammation has been linked to cardiovascular diseases. Cholesterol gets deposited in the lining of blood vessels and acts as an insult, Walker said. Because the cytokines that respond to these insults are in the bloodstream, they can lead to systemic inflammation. Inflamed blood vessels and growing fatty plaque can cause blockages and blood clots, which can cause heart attacks. 

People with chronic inflammation from an autoimmune disorder may be at greater risks for heart disease. A large-scale study at Stanford University found that coronary artery disease risk might be linked to genes associated with inflammation. 

Additionally, some scientists theorize that the bacteria from gum disease can make its way to the heart or blood vessels, acting as an insult and causing inflammation that increases the chance of a heart attack, according to the Mayo Clinic.  

Diabetes

According to a 2009 article in the journal Gerontology, cytokines can interfere with insulin signaling, resulting in increased insulin resistance and spiked blood sugar. The spikes trigger white blood cells to attack, and inflammation continues. In addition to increasing the risk for diabetes, insulin resistance can also increase the risk of weight gain. 

Lung issues

Chronic inflammation in the lungs is a factor in many problems, such as asthma, chronic obstructive pulmonary disease (COPD), which includes chronic bronchitis and emphysema, and infections, according to the Lovelace Respiratory Research Institute. When lungs are inflamed, fluid can accumulate, and the airways can narrow, making breathing difficult. 

Bone health

According to a 2009 article in the Journal of Endocrinology, chronic inflammation is associated with increased bone loss and lack of bone growth. Scientists theorize that cytokines in the blood interfere with bone “remodeling,” the process in which old, damaged pieces of bones are replaced with new ones. Furthermore, inflammation in the gut can decrease the absorption of nutrients that are important to bone health, like calcium and vitamin D.  

Depression

A 2015 study in JAMA Psychiatry found that people with depression had 30 percent more brain inflammation than those who were not depressed. Furthermore, inflammation has been linked to symptoms of depression, including feeling down, loss of appetite and sleep problems. Scientists remain unsure of why inflammation is linked to sleep problems or low moods, but suspect that cytokines can interfere with hunger signals. 

Cancer

According to the Mayo Clinic, it is not fully clear if chronic inflammation can be a contributing factor in developing cancer, but scientists are investigating. According to Cancer Research UK, immune cells attack fledgling tumors in an inflammatory response. These immune cells infiltrate the tumor, but instead of killing it, the tumor uses the nutrients and oxygen that are part of the inflammatory response to grow. 

Additionally, a chronic inflammatory response can trigger the loss of proteins involved in DNA repair, which can lead to gene mutations, according to a 2011 study in Proceedings of the National Academy of Sciences of the United States of America

Anger disorders and aggressive behavior

One study found that people with intermittent explosive disorder had higher levels of inflammatory markers, such as C-reactive proteins (CRP). Scientists are unclear what causes the link between these two factors. 

Anti-inflammatory diets have become popular in recent years. Hard evidence is lacking regarding the effectiveness of these diets in reducing inflammation, according to the Mayo Clinic, but the principles of an anti-inflammatory diet are healthy ones. The recommended foods are typical of a Mediterranean diet and include eating more fish, fresh fruits and vegetables and healthy fats; eating moderate portions of nuts; eating very little red meat; and drinking moderate amounts red wine. 

Ximena Jimenez, a Miami-based nutritionist and national spokesperson for the Academy of Nutrition and Dietetics, said consuming omega-3 fatty acids is important. “Anti-inflammatory food components, such as omega-3, protect the body against the possible damage caused by inflammation,” she said. On a cellular level, omega-3 fatty acids inhibit an enzyme that produces prostaglandins, which trigger inflammation. It’s similar to how aspirin works. 

Nutritionists also recommend incorporating more of the following foods into your diet: 

  • Cold-water fish: These are among the best sources of omega-3 fatty acids. Jimenez recommended salmon, herring, tuna and mackerel and advised consuming two or three servings (about 12 ounces or 340 grams) per week.
  • Avocados: “Avocados have great anti-inflammatory properties,” said Laura Flores, a San Diego-based nutritionist. They contain “phytosterols, carotenoid antioxidants, omega 3 fatty acids and polyhydroxolated fatty alcohols” — compounds that can help reduce inflammation. A 2013 study in the journal Food & Function found that people who ate a hamburger with avocado had lower CRP levels four hours after eating than those who did not. 
  • Broccoli and other cruciferous vegetables: Broccoli, Brussels sprout, kale and cauliflower and other green leafy veggies contain sulforaphane, which is associated with blocking enzymes that are linked to joint deterioration and, consequently, chronic inflammation, according to Victoria Jarzabkowski, a nutritionist with the Fitness Institute of Texas at the University of Texas at Austin. Sulforaphane also may be able to prevent or reverse damage to blood vessel linings caused by chronic blood sugar problems and inflammation.
  • Watermelon: Watermelon contains lycopene, a cellular inhibitor for various inflammatory processes. It also works as an antioxidant to neutralize free radicals. Additionally, watermelon contains choline, which helps keep chronic inflammation down, according to a 2006 article published in Shock medical journal.
  • Walnuts and other nuts: Jimenez said that these are another great source of omega-3 fatty acids. 
  • Onions: Their anti-inflammatory properties have made them a popular home remedy for asthma for centuries. Onions are a good source of quercetin, which inhibits histamines known to cause inflammation, according Jimenez. 
  • Olive oil and canola oil: Jimenez recommended using these as primary cooking oils, because they are a good source of omega-3 fatty acids. 
  • Berries: According to a review in the Journal of Agricultural and Food Chemistry, polyphenol compounds, particularly anthocyanins, which produce dark red pigments, moderate inflammation.
  • Whole grains: Whole grains like brown rice, quinoa and bulgur wheat have been associated with decreased CRP levels, according to studies in the journal Molecular Nutrition & Food Research and in the Journal of Nutrition. Another study in the Journal of Nutrition found that people who ate fewer whole grains actually had higher inflammation markers. The fiber in whole grains can help mediate inflammatory processes by helping with weight loss and feeding beneficial gut bacteria associated with lower levels of inflammation, according to the Arthritis Foundation
  • Certain spicesThe University of Wisconsin lists ginger, rosemary, turmeric, oregano, cayenne, cloves and nutmeg as possessing anti-inflammatory compounds that inhibit the biochemical process of inflammation. 

The most common anti-inflammatory drugs are over-the-counter medications such as aspirinnaproxen (Aleve), and ibuprofen (Advil and Motrin). They are used to treat fever, pain and swelling. They are often used for short-term afflictions like headaches, fevers associated with colds and flus, menstrual periods and strained or sprained muscles. They can also be used to treat more chronic conditions such as arthritis and back pain, though often this is done at a doctor’s discretion. In prescription doses, they are sometimes used for post-surgery pain relief, according to the National Institutes of Health

These drugs are called non-steroidal anti-inflammatory drugs (NSAIDS). They work by blocking the enzyme cyclooxygenase, which produces prostaglandins, according to MedicineNet. Without cyclooxygenase, the swelling, pain and fever of inflammation do not happen. 

Other anti-inflammatory drugs include corticosteroids, which are often found in inhalers for people with asthma. Corticosteroids reduce inflammation and swelling by reducing the production of chemicals involved in inflammation. They reduce the activity of white blood cells, too, thereby potentially impacting immunity, according to the Cleveland Clinic

Scientists are researching NSAIDS as a potential treatment or prevention for cancer, but so far have not produced definitive results according to the Mayo Clinic.

People concerned with chronic inflammation should adopt diet and lifestyle changes rather than wait for drugs, which according to the Harvard Medical School, are “a long way off, bound to be expensive and will almost certainly have side effects.”

A variety of dietary supplements are associated with anti-inflammatory responses. The Mayo Clinic advises that supplements are not regulated by the Food and Drug Administration for safety and effectiveness. With that in mind, popular supplements include:

  • Devil’s claw: This is widely used in Europe as an anti-inflammatory agent, according to the Mayo Clinic, which also said studies suggest it is effective in the short-term treatment of pain associated with osteoarthritis.
  • Cat's claw: This herb may ease rheumatoid arthritis joint pain and osteoarthritis knee pain, but more studies are needed, according to the Mayo Clinic.
  • Turmeric: This spice is well known for its anti-inflammatory compounds, called curcuminoids, according to the University of Maryland Medical Center.
  • Mangosteen: The Mayo Clinic reports that mangosteen has anti-allergy, antibacterial, anti-inflammatory, antifungal and antihistamine properties. 
  • Frankincense: This is a well-known anti-inflammatory used for centuries in Ayurvedic medicine, according to the Memorial Sloan Kettering Cancer Center. It helps prevent chemical reactions involved in inflammation. 
  • Willow bark: This supplement can ease pain and inflammation, according to the University of Maryland Medical Center. It contains salicin, a chemical similar to that in aspirin. Aspirin actually contains a chemically synthesized version of willow bark’s salicin. 

This article is for informational purposes only, and is not meant to offer medical advice. 

Additional resources