Anti-Inflammatory Diets

Anti-inflammatory diets are used to prevent or treat inflammation, which is the body's immune reaction to an injury or an irritation. There are two types of inflammation: acute and chronic. Acute inflammation is the body's response to an injury like a wound, broken bone, or bee sting. It is a normal reaction and helps the body heal. Chronic inflammation, also known as low-grade or systemic inflammation, is the body's reaction to any irritation that it regards as a foreign substance. Possible irritants include germs, cigarette smoke, and excess weight. Chronic inflammation is associated with arthritis and chronic conditions such as obesity, heart disease, some cancers, and diabetes.

Foods like oily fish (which are rich in omega-3 fatty acids), fruits, and vegetables are part of an anti-inflammatory diet. Foods and nutrients thought to trigger chronic inflammation include red meat, full-fat dairy products, processed foods, and saturated and trans fats.

Anti-inflammatory diet

The discovery of the relationship between inflammation and chronic disease grew out of laboratory and clinical studies to develop therapies for pneumococcal pneumonia. In 1930, William S. Tillett and Thomas Francis Jr. discovered a new antigen of the bacteria pneumococcus. The substance was later identified as C-reactive protein (CRP). The body produces CRP in the liver in response to injury and infection. High levels of the protein signify acute general inflammation in the body. CRP tests are also used to monitor patients with inflammatory diseases like rheumatoid arthritis.

Chronic inflammation may be the continuation of acute inflammation or a low-grade form of inflammation caused by the body's mistaken reaction to a threat that does not exist. For example, fat cells can produce certain proteins that may trigger defensive mechanisms in the body. A number of organizations, including the Arthritis Foundation, recommend weight loss (if needed) to help reduce inflammation. Anti-inflammatory diets are based on the theory that certain foods provoke inflammatory responses.

Inflammation is the localized immune reaction of body tissue to an injury, such as a cut or a fracture. It can also be a response to an irritation, such as bacteria, viral infection, trauma, cigarette smoke, chemicals, or heat. Inflammation is characterized by redness, swelling, heat, pain, and sometimes loss of function or mobility. The acute inflammation process starts with the dilation of the blood vessel, which results in increased blood flow to the affected area. The increased blood flow causes the heat and redness; the dilation produces the swelling. Pain is caused by the release of the messenger compounds that send white blood cells to kill the foreign substance.

The cells produce different types of proteins called cytokines that serve in different functions in the body; they may be released into the bloodstream or into tissue. The cytokines in the immune system are interferon, interleukins, and tumor necrosis factor-alpha (TNF-alpha). The cytokines act as messengers between cells and regulate inflammatory responses. Some cytokines are involved in acute inflammation, and others are involved in chronic inflammation.

Prostaglandins serve different functions in the body that include the activation of the inflammatory response. Prostaglandins are unsaturated carboxylic acids that are synthesized by the body from arachidonic acid, an omega-6 fatty acid. Leukotrienes are products of arachidonic acid metabolism. The body releases these chemicals in response to an allergen. Leukotrienes take place in leukocytes, which are white blood cells. During the inflammation process, leukocytes protect the body from threats such as viruses and bacteria.

Chronic inflammation is related to conditions including obesity, metabolic syndrome, asthma, allergies, irritable bowel disease, celiac disease and other digestive system diseases, stress, and sleep disorders such as sleep apnea. According to the American Heart Association (AHA), inflammation has not been proven to cause heart disease, but it is a common symptom of heart disease and stroke. Risk factors for inflammation include smoking cigarettes, high blood pressure, and low-density lipoprotein (LDL) cholesterol, also known as “bad” cholesterol.

General medical treatments for inflammation include relaxation therapies, moderate exercise such as walking, weight maintenance or loss, and medications designed to reduce the inflammation and control pain. These medications may include ibuprofen or aspirin, nonsteroidal anti-inflammatory drugs (NSAIDs), or steroid medications. NSAIDs are widely used as the initial form of therapy. However, use of these medications may irritate the stomach and could cause other complications, including the risk of stomach bleeding for people who are 60 or older.

Dietary recommendations for preventing some conditions associated with inflammation, including rheumatoid arthritis, obesity, diabetes, and stress, include eating a healthy diet, getting regular physical exercise, losing weight if necessary, and not smoking. Chronic inflammation is linked to excess weight and obesity because fat cells create cytokines, the proteins that stimulate inflammation. Inflammation and obesity are also linked to high blood pressure and elevated levels of lipids such as triglycerides and cholesterol. Inflammation and being overweight or obese place a person at risk for conditions including heart disease, diabetes, stroke, and arthritis. Excess weight places stress on the body that includes pressure on joints such as the knees.

Acute inflammation is caused by injuries such as wounds, bites, and bee stings. Treating severe injuries may involve a special diet. The Cleveland Clinic recommends that injured people eat a variety of foods from the five food groups to obtain the calories, proteins, and minerals needed for healing. The healing process for a severe wound requires an increase in calories. The Clinic also recommends consumption of “power foods,” which include:

There is no one anti-inflammatory diet. Rather, there are several healthy eating plans and recommendations designed around foods believed to decrease inflammation, as well as foods to avoid. Many popular diets, such as the Zone diet, the Perricone diet, and Dr. Weil's diet, claim to help prevent and treat inflammation. Organizations such as Harvard Medical School and the Arthritis Foundation also offer anti-inflammatory diet recommendations.

GENERAL RECOMMENDATIONS. Many professional organizations offer recommendations on what foods reduce inflammation. Harvard Medical School's Family Health Guide attributes acute inflammation to “modern irritations like smoking, lack of exercise, high-fat and high-calorie meals, and highly processed foods.” The guide contains recommendations about foods that either relieve or promote inflammation. Suggestions from the guide include:

The Arthritis Foundation website provides recommendations similar to those found in the Harvard guide, highlighting the need for omega-3 fatty acids in the diet as well as consumption of vegetables, fruits, nuts, and small amounts of dark chocolate.

MEDITERRANEAN DIETS. According to an article in the Mayo Clinic Health Letter by Brent Bauer, MD, there is limited evidence that anti-inflammation diets work directly to stop inflammation. However, foods recommended in anti-inflammatory diets are often typical of the Mediterranean style of eating and are generally good choices. Key components of Mediterranean diets include:

POPULAR DIETS. Mainstream anti-inflammatory diets include the 2005 book Healthy Aging: A Lifelong Guide to Your Physical and Spiritual Well-Being by Andrew Weil, MD. Weil is the founder of the Arizona Center for Integrative Medicine at the University of Arizona and designed the diet to reduce the risks of age-related diseases and to optimize health. His diet recommendations are based on the glycemic load (GL), a measure of the effect of food on blood sugar. Low GL recommendations include consuming lean protein, healthy fats, and high quantities of fiber from fruits and vegetables. Weil advises people to swap meat and poultry for fish and vegetable proteins such as beans, soy foods, grains, and nuts. Foods to avoid or give up include fast food, processed foods, and products made with flour or high-fructose corn syrup.

Barry Sears, developer of the Zone diet, wrote about how that particular eating plan could be used to fight inflammation in his book The Anti-Inflammation Zone: Reversing the Silent Epidemic That's Destroying Our Health. Sears used the 40:30:30 framework of his Zone diet—40% of daily calories from carbohydrates, 30% from protein, and 30% from fat—to build an anti-inflammatory plan with an emphasis on fish, vegetables, berries, olive oil, almonds, avocados, and spices.

Fish, including tuna, shellfish, and crab; Brazil nuts; and whole-wheat products are good sources of selenium, a trace mineral essential to health. Selenium is incorporated into proteins to make selenoproteins, which are important antioxidant enzymes. The antioxidant properties of selenoproteins include an important role in the cell's defense system. Selenium may be useful in preventing arthritis and other inflammatory conditions, according to Arthritis Today.

Flavonoids are a type of antioxidant thought to have anti-inflammatory effects. Flavonoids may help to prevent arthritis and provide pain relief. Sources of flavonoids include fruits, such as blueberries, blackberries, strawberries, apples, and citrus fruits; dark chocolate; red wine; legumes; and vegetables such as broccoli, celery, thyme, hot peppers, onions, kale, and scallions. Diets high in legumes are also inversely related to plasma concentrations of CRP. Isoflavones are a subcategory of flavonoids that are found in soymilk and other soy foods such as soybeans, edamame, tofu, and tempeh.

Herbs and spices are also recommended in some anti-inflammatory diets because of their antioxidant properties. However, they would need to be consumed in large amounts to have any antioxidant effect. Herbs and spices are useful as flavor replacements for less healthy recipe ingredients such as salt, sugar, and saturated fats.

Diet and exercise help to maintain a healthy weight and to prevent inflammation and reduce the risk of developing chronic diseases. Furthermore, the combination of diet and exercise is usually accompanied by an elevation of energy and emotional health.

People should consult with their doctors before beginning a new diet. Women who are pregnant or breastfeeding should also discuss the consumption of fish with their doctors, due to the risk of mercury contamination.

There is some support for the belief that food sensitivities or allergies to foods may be a trigger for inflammation. Often hard to detect with common blood tests, some people have seen alleviation of symptoms of chronic diseases, such as arthritis, when the aggravating foods are removed from their diet. Common allergic foods are milk and dairy, wheat, corn, eggs, beef, yeast, and soy.

In general, the recommendations provided by trusted organizations such as Harvard and the Mayo Clinic are in line with the federal guidelines for nutrition and provide no risks. However, people with diabetes or other chronic conditions should not change their diet without discussing it with their doctor. Also, anyone taking medication to treat a condition should not stop taking that medication without their physician's consent.

The benefits of a healthy diet and regular physical activity are widely accepted; however, it is not as clear whether certain foods reduce or relieve the symptoms of chronic inflammation. The strongest evidence-based recommendations to reduce or prevent inflammation are for people to eat a healthy diet, lose weight if needed, and not smoke.

Whole grains and whole-grain foods have been shown in some studies to decrease inflammatory markers. However, other research, such as the WHOLEheart study in the United Kingdom, found no change in markers for the risk of cardiovascular disease when whole grain intake was significantly increased, according to the July 2010 issue of the British Journal of Nutrition. Inflammatory markers were among the measurements used in the 16-week study, which involved 316 people between the ages of 18 and 65.

See also Celiac disease ; Food sensitivities ; Inflammatory bowel disease ; Omega-3 and omega-6 fatty acids ; Perricone diet ; Phytonutrients ; Soy ; Trans fats ; Triglycerides ; Zone diet .

Megan C. M. Porter, RD, LD
Revised by Liz Swain