Spondylitis — also called spondyloarthritis — is a group of autoimmune conditions that causes pain, inflammation, and damage to the joints and tissues in your spine, neck, ribs, and hips (in other words, your axial skeleton). The many subtypes of spondylitis are divided by symptoms and by age of onset. Spondylitis can also affect peripheral joints, like those in your arms and legs.

Certain risk factors have been identified for spondylitis, such as:

• Genetics
• Environment
• Smoking
• Gut bacteria changes

The bacteria in the microbiome of your gut (gastrointestinal tract) may be part of what triggers the autoimmune response that leads a person to develop spondylitis. There are two particular subtypes of spondylitis that may be connected to this chain reaction: psoriatic arthritis and ankylosing spondylitis.

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 gastrointestinal (GI) tract.

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

• 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 continuing throughout your life, your gut microbiome is ever-evolving. Over time, it becomes highly diverse. But there are some things that can reduce your gut microbiome diversity. When this happens, some microbes may not function correctly, and that can cause an autoimmune response.

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

• Diet history (including whether you were breastfed or not)
• Delivery at birth (vaginal or C-section)
• Genetics
• Current diet
• Stress level
• Antibiotic use
• Infection history
• Virus history
• Disease history

The Link Between Gut Health and Spondylitis

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 an autoimmune disease, like spondylitis.

Here’s how that might happen.

Dysbiosis

When the bacteria makeup of your GI tract becomes unbalanced, you are experiencing gut dysbiosis. Gut dysbiosis is associated with inflammatory bowel diseases (IBD), like Crohn’s disease and ulcerative colitis. It’s also linked to other chronic diseases, like type 1 diabetes and celiac disease. A small-scale study in Australia made a similar connection between people who had an unbalanced gut microbiome and certain types of spondylitis. Specifically, participants in the study with psoriatic arthritis and ankylosing spondylitis were revealed to have significantly low levels of gut bacteria and their gut microbiomes also lacked diversity.

How a GI Problem Can Become a Joint Problem

Studies have found that gut dysbiosis can also lead a person to experience intestinal permeability (”leaky gut syndrome”). Leaky gut syndrome occurs when bad bacteria creates holes or leaks in your GI tract. Such leaks lead to GI inflammation and impact the bacteria that naturally occurs in the digestive system. And there are other consequences.

Leaks can also allow outside bacteria, toxins, and other substances (antigens) into your GI system. Once those antigens are in your gut, they can then enter your bloodstream. When such antigens travel to your joints and tissues, your body reacts with an autoimmune response. That’s when you experience a flare of spondylitis symptoms.

Environment Factors Into Gut Health

Each person’s environment plays a huge role in shaping their immune system. In one Chinese study from 2020, mice with the gene HLA-B27 — a gene that can increase a person’s risk to develop spondylitis — were raised in a sterile environment (free of germs). Those mice did not develop ankylosing spondylitis. But more than 80 percent of the other mice with the HLA-B27 gene that were raised in a nonsterile environment and were exposed to common gut bacterias did develop ankylosing spondylitis.

Medicines Can Contribute to a Bad Gut

Researchers have also found that certain medications can negatively affect your gut bacteria, change your gut microbiome diversity, and lead to your gut barrier dysfunctioning. These medicines include some immunosuppressive drugs, biologics, and nonsteroidal anti-inflammatory drugs (NSAIDs).

Ways To Optimize Your Gut Health

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

Diet

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

Read more about the anti-inflammatory diet for spondylitis.

Lifestyle Changes

Some lifestyle changes have been found to increase the diversity of a person’s microbiome. Adopting healthy lifestyle habits such as daily exercise, good sleep habits, stress management, and quitting smoking can be beneficial for your gut health. Also, quitting smoking has been shown to slow down disease progression and improve the quality of life in some individuals.

Find Your Team

MySpondylitisTeam is the social network for people with spondylitis and their loved ones. On MySpondylitisTeam, more than 73,000 members come together to ask questions, give advice, and share their stories with others who understand life with spondylitis.

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