Rheumatoid arthritis & your microbiome

Rheumatoid arthritis (RA) is a chronic autoimmune disease that primarily affects the joints, causing pain, swelling and stiffness. Over time, if nothing is done, then the persistent inflammation can lead to joint damage and potentially disability.

While medications play a central role in treatment, researchers are now uncovering an important piece of the puzzle, namely, our gut microbiome.

Your gut houses trillions of bacteria, fungi and viruses that not only support digestion, but also interact with your immune system. Since rheumatoid arthritis is an immune-driven condition, the idea that gut health could influence disease activity is both fascinating and empowering – as it’s something you can do something about via diet, microbiome testing, targeted supplementation and lifestyle changes.

What’s the link between rheumatoid arthritis and gut health?

Scientists have known for decades that infection and immune dysfunction play a role in rheumatoid arthritis[1,2], but more recent research has highlighted gut dysbiosis – an imbalance in gut bacteria – as a possible trigger. Studies have found that even in the early, preclinical stages of rheumatoid arthritis, patients often show alterations in their gut microbiome[3]. This suggests that gut health may influence not just how rheumatoid arthritis develops but also how it progresses.

Put simply, the healthier and more robust your microbiome, the more likely it is to regulate inflammation rather than fuel it.

How gut dysbiosis may drive rheumatoid arthritis

Although the full picture is still emerging, several mechanisms help explain why gut health and Rheumatoid Arthritis are linked:

• Inflammatory regulation – some bacteria trigger inflammation, while others calm it down. An overgrowth of pro-inflammatory microbes can overstimulate the immune system, worsening joint inflammation.  
• Leaky gut (aka intestinal permeability) - this is when the gut lining, which normally acts as a barrier keeping harmful compounds out of circulation, may weaken. This allows bacterial toxins to escape into the bloodstream and drive systemic inflammation. You may be more likely to have a leaky gut with rheumatoid arthritis, and again, this is something you can do something about.
• Molecular mimicry – this is when certain bacterial proteins resembling human proteins found in joints are targeted by the immune system, which may then also mistakenly attack joint tissue.
• Hormone interactions – this is also influenced by gut bacteria. As rheumatoid arthritis is more common in women, fluctuations in oestrogen and progesterone may partly explain why microbiome imbalances affect disease risk.

When considered together, these pathways help explain why rheumatoid arthritis is not just a joint disease but a systemic one – and also why gut health matters so much.

The impact of rheumatoid arthritis treatment on the gut

The medicines used to control rheumatoid arthritis – such as NSAIDs, corticosteroids and DMARDs – are essential for reducing inflammation and preventing long-term joint damage. But they also come with side effects, one of which is their impact on gut bacteria. These treatments can reduce microbial diversity, sometimes leading to bloating, loose stools or increased susceptibility to gut imbalances.

This does not mean treatment should be avoided, but it does highlight the importance of supporting gut health alongside medical care. A healthier gut microbiome may improve tolerance to medications and even enhance their effectiveness.

Foods that support a healthy gut

Food is one of the most powerful ways to shape your microbiome. It’s not about eating perfectly or following a rigid diet but about consistently adding in more of the foods that nourish beneficial bacteria and reduce inflammation [4].

Some of the most supportive foods for people with rheumatoid arthritis include:

• Fermented foods – live yoghurt, sauerkraut, kimchi and miso provide probiotics to top up beneficial bacteria.
• Prebiotic foods – garlic, onions, leeks and asparagus act as a fertiliser for good bacteria.
• Fibre-rich foods – wholegrains, legumes, fruits and vegetables feed gut microbes and help regulate bowel movements.
• Omega-3 fatty acids – found in oily fish, flaxseeds and walnuts, these fats reduce inflammation and may ease joint pain.
• Polyphenol-rich foods – berries, green tea, extra virgin olive oil and dark chocolate provide antioxidants that protect both gut and immune health.

The more variety, the better. Think of your microbiome as a forest – diversity in your diet creates diversity in your gut, which supports balance and resilience.

The role of lifestyle

Diet is just one piece of the puzzle. Lifestyle also has a significant effect on your gut and immune system. Factors such as stress, poor sleep and lack of movement can all disrupt the microbiome. Clients often state that stress makes their arthritis symptoms worse, and science supports this link between the nervous system, immunity and gut health.

That’s why long-term changes matter more than quick fixes. A diverse diet combined with good sleep, stress management and movement creates the best environment for both your gut and your joints. 

Gut microbiome testing and why it’s so helpful

One of the most exciting tools in personalised nutrition is advanced gut testing. By analysing the balance of bacteria in your digestive tract, we can better understand what may be driving inflammation and tailor strategies accordingly.

The benefits of testing include:

• identifying dysbiosis and specific microbial imbalances
• highlighting how diet and medication may be influencing your gut
• guiding personalised nutrition plans to restore balance
• supporting digestive comfort (less bloating, diarrhoea or constipation)
• helping monitor progress and response to dietary and lifestyle changes

This kind of insight can be particularly valuable if you’ve tried multiple diets without much success or if you’re on long-term rheumatoid arthritis medication and want to support your gut health more proactively.

Putting research into practice

While there is still much to learn, experts agree on three take-home points:

1. Your microbiome matters – while gut health may not be the cause of rheumatoid arthritis, it strongly influences symptoms and inflammation.
2. Balance is key – no single “bad bug” explains rheumatoid arthritis. Instead, the overall balance of microbes determines whether your immune system is calm or overactive.
3. Lifestyle wins out – probiotics and supplements can help, but the biggest impact comes from sustained lifestyle changes – dietary variety, movement, stress management and sleep.

In other words, your microbiome is shaped over months and years, not days. The good news is that even small, consistent shifts in your eating habits and lifestyle can have long-lasting benefits for your joints and overall well-being.

If you’re interested in exploring the benefits of gut microbiome testing and learning how to support your gut health for rheumatoid arthritis management, book a discovery call with a nutritional therapist who can help you navigate what might be the best options for you.

References

1. Zhao T, Wei Y, Zhu Y, Xie Z, Hai Q, Li Z, Qin D. Gut microbiota and rheumatoid arthritis: From pathogenesis to novel therapeutic opportunities. Front Immunol. 2022 Sep 8;13:1007165. doi: 10.3389/fimmu.2022.1007165. PMID: 36159786; PMCID: PMC9499173.
2. Romero-Figueroa MDS, Ramírez-Durán N, Montiel-Jarquín AJ, Horta-Baas G. Gut-joint axis: Gut dysbiosis can contribute to the onset of rheumatoid arthritis via multiple pathways. Front Cell Infect Microbiol. 2023 Jan 27;13:1092118. doi: 10.3389/fcimb.2023.1092118. PMID: 36779190; PMCID: PMC9911673.
3. Gilbert BTP, Tadeo RYT, Lamacchia C, Studer O, Courvoisier D, Raes J, et al. Gut microbiome and intestinal inflammation in preclinical stages of rheumatoid arthritis. RMD Open. 2024;10:e003589. https://doi.org/10.1136/rmdopen-2023-003589
4. Cutolo M, Nikiphorou E. Nutrition and Diet in Rheumatoid Arthritis. Nutrients. 2022 Feb 19;14(4):888. doi: 10.3390/nu14040888. PMID: 35215538; PMCID: PMC8878187.