What Do We Know About Foods and Inflammation?

Asthma, rheumatoid arthritis, type 2 diabetes, psoriasis and obesity are some conditions with which chronic inflammation (inflammation) can occur.

Research shows that people with these conditions may have higher levels of inflammatory markers in their bodies. Although many factors play a role in inflammation, some foods may increase or reduce symptoms.

What Is Inflammation?

There are two main types of inflammation: acute and chronic.

• Acute inflammation is the body's rapid response, increasing blood flow to an affected area such as a wound or infection. White blood cells help rebuild damaged tissue, and acute inflammation generally stops when the wound heals.
• Chronic inflammation is a long-term condition that can develop gradually over months and years. Causes of chronic inflammation may include:
  • Long-term infection
  • Exposure to toxic chemicals
  • Autoimmune disorders
  • Autoinflammatory disorders
  • Repeated episodes of acute inflammation
  • Oxidative stress in the body

Risk factors for chronic inflammation:

• Older age
• Obesity
• Smoking
• Low testosterone and estrogen levels
• Physical and emotional stress, sleep disorders

Processed foods, saturated fats, trans fats and refined sugar may increase the risk of proinflammatory molecules. This may be particularly relevant if a person is overweight or has diabetes.

What Foods Cause Inflammation?

Many foods may worsen symptoms of inflammation. These include sugar, trans fats, refined carbohydrates, and red or processed meat.

Sugar

According to a 2018 systematic review of many studies, a high-sugar diet may affect chronic inflammation by increasing inflammatory markers in the blood.

Another 2018 study found that excessive sugar consumption may increase inflammatory markers in children and lead to chronic inflammation. The study compared a 46% reduction in daily sugar with an 11% reduction in proinflammatory markers in 11 children. Researchers suggest that reducing sugar-sweetened beverage consumption during childhood may have beneficial future health outcomes.

Another article published in 2018 suggests that fructose may cause cellular inflammation. Excess fructose may also increase fat around abdominal organs and the amount of fat in the liver.

Trans Fat

Trans fats may increase inflammatory markers and the risk of chronic inflammation that can lead to conditions such as diabetes and cardiovascular disease. They also raise low-density lipoprotein (LDL) levels while lowering high-density lipoprotein (HDL), a combination that may increase heart disease risk.

Although beef and dairy products contain small amounts of naturally occurring trans fats, most trans fats arise when manufacturers add hydrogen to vegetable oil. Trans fats may appear on labels as hydrogenated oil and may occur in processed foods, baked goods, fried foods and margarine.

- Related topic: What should cholesterol (HDL, LDL, triglyceride) levels be by age?

Refined Carbohydrates

Refined carbohydrates have a high glycemic index, which may increase a type of protein called advanced glycation end products (AGEs) that can increase inflammation. 

Refined carbohydrates include white-flour products such as:

• White bread and sandwich bread
• Some crackers
• White rice
• Some cereals

Red and Processed Meat

Red and processed meats are high in saturated fats that can cause inflammation in fatty tissue. Data from 2016 suggest that red and processed meat are linked to an increased inflammatory response in the body and may increase colon cancer risk.

- Related topic: Red Meat: Pros and Cons

How Does Inflammation Affect Health?

According to the National Cancer Institute, inflammation can cause DNA damage that may lead to cancer. Chronic inflammation is also linked to inflammatory bowel diseases, such as ulcerative colitis and Crohn's disease, that may increase colon cancer risk. Inflammation is commonly present in people with heart disease and stroke and may be linked to plaques forming in arteries.

Other inflammatory conditions include:

• Diabetes
• Chronic kidney disease
• Non-alcoholic fatty liver disease
• Autoimmune conditions such as lupus
• Neurodegenerative conditions such as Alzheimer's disease
• Arthritis and joint disorders
• Allergy and asthma
• Chronic obstructive pulmonary disease (COPD)

What Are Anti-Inflammatory Foods and Diets?

Inflammation is generally part of the body's healing process and may also help fight disease. However, if someone has recurring or persistent low-level inflammation, certain foods and diets may help reduce symptoms.

Foods

Foods high in sugar or processed foods may worsen inflammation, while a healthy eating plan based on fresh foods such as vegetables and fruit may help reduce symptoms.

Foods that may have anti-inflammatory effects include:

• Fruit and vegetables: Many fruits and vegetables, such as strawberries, apples and cruciferous vegetables, are rich in antioxidants and polyphenols that may have anti-inflammatory effects.
• Fiber: Arthritis Foundation reports that increasing dietary fiber may help lower certain inflammatory cytokines.
• Fish oils: Some fish oils contain omega-3 fatty acids that may help lower the body's inflammatory protein levels.
• Nuts: Some nuts may help reduce the risk of cardiovascular disease and diabetes.
• Turmeric: Curcumin in turmeric may help improve inflammatory health problems.

Diets

In addition to healthy eating plans, some people may find that specific diets have a beneficial effect on inflammation.

Mediterranean Diet

Research shows that the Mediterranean diet may have a powerful anti-inflammatory effect and protect the body against symptoms of chronic inflammatory diseases such as cancer, diabetes and metabolic syndrome. It may also help reduce symptoms and inflammation's effects on the cardiovascular system.

The Mediterranean diet includes:

• Greater consumption of plant foods, including fruit, vegetables, nuts, seeds, legumes and olive oil
• Moderate consumption of fish, seafood, yogurt, cheese and milk
• Low consumption of red and processed meat
• Low consumption of sugary foods

DASH

DASH (Dietary Approaches to Stop Hypertension) is another diet that may help reduce inflammation symptoms. Research on the diet for blood pressure management was funded by the National Institutes of Health (NIH).

A 2017 review of studies on DASH showed that it improved circulating inflammatory biomarkers in adults and may help reduce inflammation in the body. The DASH diet limits saturated fats, trans fats, sugary drinks, sweets and salt. It focuses on consuming:

• Vegetables and fruit
• Whole grains
• Fat-free or low-fat dairy products
• Poultry
• Fish
• Beans and related varieties
• Tree nuts
• Vegetable oils

Summary

Inflammation is part of the body's healing process, but some medical conditions harm the immune system and cause recurring or persistent low-level inflammation.

Some foods, such as fresh fruit and vegetables, whole grains, fish oils, nuts, legumes and olive oil, may help ease inflammation symptoms. Certain anti-inflammatory diets may also reduce or prevent inflammation.