Growing evidence suggests the microbiome of people’s guts — our gastrointestinal (GI) tracts — plays a role in inflammatory and autoimmune diseases. Rheumatoid arthritis (RA), a type of arthritis in the joints, has been singled out especially in the findings.

In fact, the research is strong enough that gut microbiome health is now on the list of identified RA risk factors — a list that already included genetics, environmental factors, and smoking. In short, it’s now thought that the bacteria in a person’s gut microbiome may be part of what triggers the immune response that leads to someone developing RA.

What Is the Microbiome?

Your gut includes your mouth, throat, esophagus, stomach, small and large intestines, rectum, and anus. Your gut microbiome — sometimes called gut flora — is the community of microorganisms that live in your body. Your microbiome includes bacteria, fungi, and viruses. There are over 100 trillion bacterial cells (or microbes) found in your GI tract.

These bacterial microbes interact with your immune system and perform many functions, such as:

• Protecting your body from harmful organisms and substances that can cause illness
• Helping with digestion (breaking down fiber)
• Producing vitamins and proteins you cannot produce on your own, such as vitamin K
• Shaping and strengthening your immune system and its response

Starting at birth and throughout your life, your gut microbiome continues to evolve. Over time, it becomes highly diverse. But there are some things that can reduce the diversity of your gut microbiome. When this happens, some microbes may not function correctly and such abnormalities can set off an autoimmune response.

Factors that can affect the diversity of your microbiome include your:

• Diet
• History of being breastfed
• Whether you were born vaginally or via C-section
• Genetics
• Stress level
• Antibiotic use
• Infection history
• Virus history
• Disease history

The Link Between Gut Health and RA

Over the past century, researchers have found that an unbalanced community of microbes in your gut leads to an autoimmune response. (“Unbalanced” means the types and amounts of your microbes are less than ideal for good gut health.) Your genetic predisposition, as well as any bacterial infections you experience (and the medicines used to treat them), can also factor into your gut health and autoimmune responses. Autoimmune responses can then develop into autoimmune diseases, like RA. Here’s how that might happen.

Dysbiosis

When the bacteria makeup of your GI tract becomes unbalanced, you experience gut dysbiosis. Gut dysbiosis is associated with inflammatory bowel diseases (IBD), like Crohn’s disease and ulcerative colitis.

Over the past decade, researchers have also found dysbiosis to be a key factor in the development of RA. Several studies have revealed that people living with RA (at any stage) had significantly lower levels of gut bacteria and their gut microbiomes also lacked diversity. Scientists identified that the bacterial group Bacilli (specifically Lactobacillus) was significantly higher in participants with RA and in RA animal models compared to healthy control groups. In fact, people with severe RA had the highest levels of Lactobacillus. These findings suggest that Bacilli bacteria may cause individuals to become more susceptible to RA. However, more research is needed to explore this association further.

Medications Can Affect Gut Health

Researchers have also found that antibiotics can negatively affect a person’s gut bacteria, change gut microbiome diversity, and potentially lead to gut barrier dysfunction. Other medications may be beneficial for your gut microbiome. One study found that certain RA medications such as methotrexate and hydroxychloroquine actually increased gut microbiome diversity in people with RA. Researchers believe that these RA drugs may play a role in helping to restore people’s gut health.

How a GI Problem Can Become a Joint Problem

Studies have found that gut dysbiosis can lead a person to experience intestinal permeability (also known as “leaky gut syndrome”). Leaky gut syndrome occurs when bad bacteria create small holes (or leaks) in your intestines. Such leaks lead to inflammation and impact the bacteria that naturally occur in the digestive system.

Leaks can also allow outside bacteria, toxins, and other substances — like antigens — into your intestines. (Antigens are molecules and particles that cause immune responses.) When an antigen gets into your intestines, it can then enter your bloodstream. From there, they can travel to your joints and tissues, and your body will respond with an autoimmune response. It’s at that point when you experience a flare of RA symptoms.

Environment Factors Into Gut Health

Each person’s environment plays a huge role in shaping their immune system. However, people who have certain antigen genes (specifically HLA-B27 and HLA-DRB1) are more genetically susceptible to developing RA.

In 2017, Japanese scientists reported that SKG mice — a strain of mice genetically predisposed to RA — did not develop RA in a sterile (germ-free) environment. It also determined SKG mice exposed to various bacteria in their environment did develop signs of arthritis. These findings suggest that the environment plays a role in the development of RA, particularly in susceptible individuals. There are other environmental and genetic factors that increase the risk of RA, however. More research is needed to explore this association further.

Ways To Optimize Your Gut Health

Some evidence shows that maximizing your gut health might help to treat your RA and to manage the symptoms you experience.

Diet

Adopting a low-fat, low-sugar, or anti-inflammatory diet might benefit some people with RA. If you are considering changing your diet, it is important to speak to your doctor first to discuss the best options for you.

“I have had really good luck cutting back on dairy. Before this I used to have flare-ups and a high disease activity. Every once in a while I have dairy, but I always feel so sick afterwards, it’s hardly worth it,” shared one myRAteam member.

Lifestyle Changes

Some lifestyle changes have been found to increase the diversity of the microbiome. Adopting healthy lifestyle habits such as daily exercise, good sleep habits, and stress management can be beneficial for your gut health. Also, quitting smoking has been shown to slow down disease progression, reduce the severity of symptoms, and improve the effectiveness of medications in some people.

Find Your Team

On myRAteam, the social network for people with rheumatoid arthritis, more than 176,000 members come together to ask questions, give advice, and share their stories with others who understand life with rheumatoid arthritis.

Are you curious about the connection between gut health and RA? Have you tried improving your gut health to manage your rheumatoid arthritis symptoms? Share your experience in the comments below, or start a conversation by posting on myRAteam.