Inflammation

Inflammation is your body’s natural defense system, responding to injuries and invaders like germs to promote healing. While this process is essential for protection, chronic inflammation that persists without reason can harm healthy tissues and contribute to many serious diseases.

Table of contents

• What is inflammation?
• Types of inflammation: Acute and chronic
• Symptoms of inflammation
• What causes inflammation?
• Diseases linked to chronic inflammation
• Measuring inflammation
• Treatment and management
• Diet and lifestyle changes

What is inflammation?

Inflammation is your body’s response to an illness, injury, or something that doesn’t belong in your body, such as germs or toxic chemicals^[1]. This process is a normal and important part of how your body protects itself and heals^[2].

When an invader like a virus tries to enter your body, or you get injured, your immune system (your body’s defense system) sends out its first responders. These are inflammatory cells (specialized cells that fight threats) and cytokines (substances that signal more inflammatory cells to come)^[1]. These cells begin an inflammatory response to trap germs or toxins and start healing injured tissue^[1].

The term inflammation comes from the Latin word “inflammare,” meaning to ignite or burn^[7]. Practitioners of ancient civilizations, including those from the time of Hippocrates, recognized and treated the signs of inflammation^[14]. The Roman encyclopedist Aulus Cornelius Celsus first identified the four main signs of inflammation: redness, swelling, heat, and pain^[7].

Types of inflammation: Acute and chronic

There are two main types of inflammation: acute and chronic. Acute inflammation is sudden and temporary, while chronic inflammation can go on for months or years^[1].

Acute inflammation

Acute inflammation is your immune system’s response to a sudden injury or illness^[1]. This type is short-lived and goes away within hours or days. It’s a response to an illness or injury, and your body sends inflammatory cells to the site of the problem so you can start recovering^[3].

When you cut your finger, for example, inflammatory cells travel to the site of injury and start the healing process^[1]. The body sends chemicals from white blood cells into your blood or tissues, which raises blood flow to the area of injury or infection. This can cause redness and warmth. Some of the chemicals cause fluid to leak into your tissues, resulting in swelling. This protective process may trigger nerves and cause pain^[3].

Infections in different parts of your body can cause sudden inflammation. For example, bacterial infections like strep throat and viral infections like the flu can cause throat inflammation^[1]. Acute inflammation may last for a few hours to a few days, depending on your condition^[1].

Chronic inflammation

Chronic inflammation occurs when your body continues sending inflammatory cells even when there’s no danger^[1]. This type can last months or years, even after the thing that triggered the inflammation is gone^[3].

In certain diseases, your body’s defense system triggers inflammation when there are no invaders to fight off^[3]. For example, in rheumatoid arthritis, inflammatory cells and substances attack joint tissues. This leads to inflammation that comes and goes and can cause severe damage to your joints^[1].

With chronic inflammation, processes that normally protect your body end up hurting it^[1]. The problem is that inflammation is an “equal opportunity offender” that can damage both diseased and healthy tissues, and the potential for ongoing inflammatory spread is ever-present^[7].

Symptoms of inflammation

The symptoms you experience depend on whether you have acute or chronic inflammation. The five cardinal signs of acute inflammation are redness, heat, swelling, pain, and loss of function^[2].

Symptoms of acute inflammation

When an injury to a specific part of your body occurs, you may notice^[1]:

• Discolored or flushed skin
• Pain or tenderness that should be mild and only in the area of the injury
• Swelling
• Skin that feels hot to the touch
• Inability to use that part of your body as you normally would (for example, reduced range of motion)

Examples of a loss of function include not being able to move an inflamed joint properly, having a worse sense of smell during a cold, or finding it more difficult to breathe when you have bronchitis^[2]. Not all inflammations cause all five symptoms. Some inflammations occur “silently” and don’t cause any symptoms^[2].

Symptoms of chronic inflammation

Chronic inflammation symptoms may be harder to spot than acute inflammation symptoms. You may have^[1]:

• Abdominal (belly) pain
• Chest pain
• Fatigue and/or insomnia
• Fever
• Joint pain or stiffness
• Mouth sores
• A skin rash
• Depression, anxiety, and other mood disorders
• Gastrointestinal (GI) issues, like diarrhea, constipation, and acid reflux
• Weight gain or weight loss
• Frequent infections

If the inflammation is severe, it can cause general reactions in the body including generally feeling ill, exhaustion, and fever. These are signs that the immune system is very active and needs a lot of energy^[2].

What causes inflammation?

If you have acute inflammation, you may know exactly what caused it: an injury or a bacterial or viral illness. The causes of chronic inflammation can be harder to figure out^[3].

Many different things can cause inflammations. The most common include^[2]:

• Pathogens (germs) like bacteria, viruses, or fungi
• External injuries like scrapes or damage through foreign objects (for example, a thorn in your finger)
• Effects of chemicals or radiation

There are many factors that can contribute to chronic inflammation. Some factors we have control over, and others we do not. These include^[15]:

• Dietary choices
• Lack of exercise
• Chronic stress
• Obesity
• Too many unhealthy microbes in your gut
• Too few healthy microbes in your gut
• Poor sleep quantity and quality
• Exposure to toxins, such as air pollution or dangerous chemicals
• Tobacco use
• Drinking too much alcohol
• Persistent viral or bacterial infections
• Allergens and environmental pollutants in air, water, and food

Consuming too many calories and being overweight, especially for those people carrying extra pounds around their midsection, leads to greater levels of inflammatory compounds^[22]. Another theory is that having excess fat cells taxes the immune system because the body views your fat cells as “foreign invaders.” To fight off the invaders, the body turns on the inflammatory response and keeps it on^[22].

Diseases linked to chronic inflammation

Chronic inflammation is involved in the disease process of many common conditions. Uncontrolled inflammation is now considered part of the disease process and is associated with many widely occurring diseases^[4].

Common inflammatory conditions include^[3]:

• Neurological conditions such as Alzheimer’s disease and Parkinson’s disease
• Autoimmune disorders such as rheumatoid arthritis, lupus, and psoriasis
• Gastrointestinal conditions such as Crohn’s disease, irritable bowel syndrome, and ulcerative colitis
• Mental health disorders such as depression and anxiety
• Cardiovascular issues such as high blood pressure and heart disease
• Lung disease such as asthma and chronic obstructive pulmonary disorder (COPD)
• Metabolic disorders such as type 2 diabetes
• Certain cancers

Many major diseases that affect us, including cancer, heart disease, diabetes, arthritis, depression, and Alzheimer’s, have been linked to chronic inflammation^[12]. Inside arteries, inflammation helps kick off atherosclerosis (the buildup of fatty, cholesterol-rich plaque). Your body perceives this plaque as abnormal and foreign, so it attempts to wall off the plaque from the flowing blood. But if that wall breaks down, the plaque may rupture. The contents then mingle with blood, forming a clot that blocks blood flow. These clots are responsible for the majority of heart attacks and most strokes^[4].

Measuring inflammation

Although measuring low-grade chronic inflammation carries some limitations, studies frequently measure cellular markers in the body^[6]. A simple blood test called the hsCRP test can measure C-reactive protein (CRP), which is a marker for inflammation, including inflammation in the arteries^[4].

When inflammation is present in the body, there will be higher levels of substances known as biomarkers (measurable signs in the body). If a doctor wants to test for inflammation, they may assess CRP levels^[10]. CRP levels tend to be higher in older people and those with conditions such as cancer and obesity^[10].

Nearly 25 years ago, Harvard researchers found that men with higher CRP levels—approximately 2 milligrams per liter or greater—had three times the risk of heart attack and twice the risk of stroke as men with little or no chronic inflammation^[4].

Changes in the blood can indicate inflammation. The levels of substances in the blood that are taken as signs of inflammation increase, including C-reactive protein (CRP), the erythrocyte sedimentation rate (ESR) (a measure of how quickly red blood cells settle), and the number of white blood cells^[2].

Treatment and management

The therapeutic approach to treating excessive inflammation has remained relatively consistent over time. Practitioners of ancient civilizations used remedies that block or inhibit inflammatory chemical messengers, and while more selective drugs are available today, this basic concept hasn’t changed much^[14].

Professional rehabilitation therapists treat pain and inflammation using techniques that make movement easier and enable people to participate more fully in recovery^[16]. Techniques used include^[16]:

• Heat therapy
• Low-level laser therapy
• Cold therapy
• Electrical stimulation
• Traction
• Massage
• Acupuncture

Heat therapy increases blood flow and makes connective tissue more flexible. It temporarily decreases joint stiffness, pain, and muscle spasms. Heat may also help reduce the buildup of fluid in tissues. Heat therapy is used to reduce pain and stiffness in people with some forms of arthritis and reduce muscle spasm with injuries such as sprains and strains^[16].

Applying cold may help numb tissues and relieve muscle spasms, pain due to injuries, and low back pain or inflammation that has recently developed^[16]. Cold may be applied using an ice bag, a cold pack, or fluids that cool by evaporation. The therapist limits the time and amount of cold exposure to avoid damaging tissues^[16].

For therapists, whether to use heat or cold therapy is often a personal choice made together with the person being treated, although cold therapy seems to be more effective for acute pain^[16].

Diet and lifestyle changes

One of the most powerful tools to combat inflammation comes not from the pharmacy, but from the grocery store^[12]. Research suggests that certain dietary components can affect the same biological pathways that are affected by drugs^[6].

Anti-inflammatory foods

An anti-inflammatory diet should include these foods^[12]:

• Tomatoes
• Olive oil
• Green leafy vegetables, such as spinach, kale, and collards
• Nuts like almonds and walnuts
• Fatty fish like salmon, mackerel, tuna, and sardines
• Fruits such as strawberries, blueberries, cherries, and oranges

Certain types of fish are rich in inflammation-fighting omega-3 fatty acids (healthy fats found in some fish and plants), which reduce C-reactive protein and other inflammatory proteins in your body. You should aim to eat at least 3 to 4 ounces of fish, twice a week. The best sources include salmon, tuna, sardines, anchovies, and other cold-water fish^[20].

Fruits and vegetables are packed with antioxidants (protective substances that fight harmful molecules), which support the immune system and may help fight inflammation. Try to eat at least 1½ to 2 cups of fruit and 2 to 3 cups of vegetables per meal. The best sources include colorful foods such as blueberries, blackberries, cherries, strawberries, spinach, kale, and broccoli^[20].

Many experimental studies have shown that components of foods or beverages may have anti-inflammatory effects. Fruits and vegetables such as blueberries, apples, and leafy greens are high in natural antioxidants and polyphenols (protective compounds found in plants)^[12].

Foods to avoid

Try to avoid or limit these foods as much as possible^[12]:

• Refined carbohydrates, such as white bread and pastries
• French fries and other fried foods
• Soda and other sugar-sweetened beverages
• Red meat (burgers, steaks) and processed meat (hot dogs, sausage)
• Margarine, shortening, and lard

Not surprisingly, the same foods that promote inflammation are generally considered bad for our health. Some of the foods that have been associated with an increased risk for chronic diseases such as type 2 diabetes and heart disease are also associated with excess inflammation^[12].

Additional lifestyle recommendations

Engaging in regular exercise not only aids weight control and body-fat reduction, but also lowers CRP levels. Aim to do at least 30 minutes of continuous activity most days of the week^[22].

Fiber is essential for gut health, and therefore overall health. Most Americans only get about 50% of the recommended daily amount of fiber. Try for 25 grams per day for women or 38 grams per day for men. Fiber comes from plant foods and there are two types. Both types are important, so include a variety of whole plant foods to help you get the recommended amount each day^[15].

There is data suggesting that alcohol may have an anti-inflammatory effect. In one study, individuals who consumed one to seven drinks a week had lower levels of inflammatory markers compared to individuals who either never drank or drank more than eight drinks per week. Clearly more is not better; two drinks per day is the maximum, and women should limit it to one per day^[22].

You can make lifestyle choices that lower chronic inflammation, rather than fueling it. In particular, your food choices have a significant impact on your health. Your diet as a whole has a large effect on the level of chronic inflammation in the body^[15].