Quick answer: Research shows links between the gut microbiome and the immune system, and people with some types of arthritis have different gut bacteria. But there is no good evidence yet that changing your gut bacteria, with diet or probiotics, treats arthritis. The best-supported way to look after your gut is a varied diet rich in fibre, aiming for the NHS target of 30g a day, with plenty of fluids.
Evidence checked on 10 October 2026 against Arthritis UK's diet research summary, the BDA probiotics fact sheet, NHS: Probiotics and published reviews.
"Heal your gut, heal your joints" is a popular message online, often linked to expensive tests, supplements and restrictive diets. The science behind the gut and arthritis is genuinely interesting, and researchers are taking it seriously. But there is a big gap between what the research has found and what is being sold. This guide explains what is known, what is not, and the simple, evidence-based ways to look after your gut.
What is the gut microbiome?
Your gut is home to trillions of bacteria and other microbes, known as the gut microbiome. They help digest fibre, make some vitamins and produce substances that keep the gut lining healthy. Arthritis UK (formerly Versus Arthritis) explains that the foods we eat can affect our gut microbiome and how it behaves, and that research has shown the gut microbiome and the immune system are linked.
The BDA notes that gut bacteria can be knocked out of balance by many things, including getting older, taking antibiotics, illnesses such as irritable bowel syndrome or inflammatory bowel disease, and food poisoning.
How might the gut be linked to arthritis?
There are several well-established and emerging links:
- Reactive arthritis. The NHS explains that reactive arthritis is where joints become sore and swollen after an infection, often a stomach infection such as food poisoning, or a sexually transmitted infection. Symptoms usually start 1 to 4 weeks after the infection and usually go away within 6 months.
- Inflammatory bowel disease. Crohn's disease and ulcerative colitis can be accompanied by joint inflammation (sometimes called enteropathic arthritis), and some types of spondyloarthritis are linked with gut inflammation.
- Differences in gut bacteria. Studies have found that people with rheumatoid arthritis and some other types of arthritis tend to have different gut bacteria from people without arthritis. It is not yet clear whether these differences help cause arthritis, result from it, or are caused by treatment and diet.
- Immune signalling. Gut bacteria interact with the immune system, which is one reason researchers think they might influence autoimmune conditions.
What the evidence shows about changing your gut
Arthritis UK states clearly that there is no evidence that making changes to the gut microbiome, either by diet or in other ways, will affect autoimmune conditions such as rheumatoid arthritis, and that probiotics have not been shown to help. It says more research is needed.
Probiotics in rheumatoid arthritis
A 2023 systematic review and meta-analysis (Wu and colleagues) combined randomised trials of probiotics and related supplements in rheumatoid arthritis. It found small improvements in disease activity scores, a disability questionnaire and some blood markers of inflammation, but no significant effect on pain scores. The authors said the findings need confirming in large clinical studies that take better account of age, disease duration and medicines. In other words, the results are interesting but not strong enough to recommend probiotics for arthritis.
Diet and gut bacteria
Some small diet studies in rheumatoid arthritis have noticed changes in gut bacteria alongside symptom changes. For example, in Norwegian research on fasting followed by a vegetarian diet, the gut flora differed between times when people improved and times when they did not. This does not prove that the bacteria caused the improvement. See our plant-based diet review for more on that research.
Osteoarthritis
Researchers are also exploring links between gut bacteria, obesity and osteoarthritis, but this is early-stage research with no proven treatments.
Evidence at a glance
| Claim | What the evidence shows |
|---|---|
| The gut and the immune system are linked | Yes, this is well established |
| Some infections in the gut can trigger arthritis | Yes, reactive arthritis can follow food poisoning |
| People with arthritis have different gut bacteria | Studies suggest so, but cause and effect are unclear |
| Probiotics treat arthritis | Not proven. Arthritis UK says they have not been shown to help |
| "Leaky gut" causes arthritis and can be cured with supplements | Not supported by good evidence |
| Home microbiome tests can tell you what to eat for your arthritis | No good evidence |
| A high-fibre, varied diet supports gut health | Yes, and it has wider health benefits |
Should I take a probiotic?
The NHS says there is some evidence that probiotics may help in some cases, such as easing some symptoms of irritable bowel syndrome (IBS), but little evidence for many of the health claims made about them. The BDA says that if you are healthy, a probiotic supplement is unlikely to be beneficial.
Situations where a probiotic may be worth discussing:
- Antibiotics. The BDA says research shows many probiotics prevent diarrhoea when taking antibiotics.
- IBS. The BDA suggests a four-week trial of a probiotic, then trying another or stopping if it does not help.
- Constipation. The BDA says certain probiotics may help ease symptoms.
Safety
The NHS says probiotics appear safe for most people with a healthy immune system, but that people with an existing health condition or a weakened immune system should talk to a doctor before taking them. The BDA gives similar advice. This matters if you take medicines that suppress the immune system, such as methotrexate, other DMARDs, biologics, JAK inhibitors or steroid tablets. Ask your rheumatology team or pharmacist before taking probiotic supplements. The NHS also notes that because of the way probiotics are regulated, you cannot always be sure what a product contains or that it will reach your gut alive.
The NHS methotrexate guidance says there is not enough information to know whether herbal remedies or supplements are safe to take with methotrexate, so tell your team about anything you take.
Before you buy a gut supplement
Gut health products are a growing market, and many make broad claims. Before spending money, ask yourself:
- Is there a specific reason for taking it, such as antibiotic-associated diarrhoea or IBS, rather than a general hope that it will help your joints?
- Does the label name the specific strains and amounts, so you know what you are taking?
- Have I checked with my rheumatology team or pharmacist that it is safe with my medicines and my immune system?
- Will I give it a fair, time-limited trial (the BDA suggests about four weeks for IBS) and stop if it does not help?
- Could the money be better spent on fibre-rich foods, which have clearer benefits?
What does help: fibre and variety
The best-supported way to look after your gut is to eat a varied diet with plenty of fibre. The NHS says government guidelines recommend 30g of fibre a day, while most adults eat only about 20g.
Fibre is found in:
- wholegrain bread, cereals, oats, brown rice and wholewheat pasta
- beans, lentils and chickpeas
- vegetables and fruit, especially with skins on
- potatoes with their skins
- nuts and seeds
The BDA explains that prebiotics, which are found in some fibre-rich foods, act like fertiliser for your gut bacteria. Foods such as onions, garlic, leeks, bananas, oats and pulses contain types of fibre that feed beneficial bacteria.
Easy ways to eat more fibre
- Swap white bread, pasta and rice for wholegrain versions.
- Have porridge or wholegrain cereal for breakfast.
- Add a tin of beans or lentils to soups, stews, curries and chilli.
- Leave the skins on potatoes.
- Keep frozen vegetables and fruit for when fresh is too much effort.
- Increase fibre gradually and drink plenty of fluids to avoid wind and bloating.
Fermented foods
Yoghurt with live cultures, kefir, sauerkraut and kimchi are popular. The BDA notes that fermented foods such as kefir and kombucha may contain beneficial microorganisms, but they are not considered probiotics because of a lack of scientific evidence about their health benefits. They can be enjoyed as part of a varied diet, but they are not a treatment for arthritis.
Arthritis medicines and your gut
Many arthritis medicines affect the digestive system, which is worth knowing when you think about gut health:
- NSAIDs such as ibuprofen and naproxen can irritate the stomach and cause indigestion, ulcers and bleeding. Take them with or after food, and your GP may prescribe a stomach-protecting medicine.
- Methotrexate can cause nausea and diarrhoea. The NHS says prescribed folic acid can reduce some of these side effects. Tell your team if they are a problem.
- Some DMARDs and biologics can cause digestive side effects. Check your medicine leaflet.
- Antibiotics, if you need them for an infection, change gut bacteria temporarily.
- Some painkillers, such as codeine, often cause constipation. Fibre and fluids help, and a pharmacist can advise on laxatives.
For full details on food and medicine interactions, see our guide to food, drink and arthritis medicines.
What about food intolerance and gut tests?
Many companies sell microbiome, food intolerance or "leaky gut" tests directly to the public. These are not used in NHS arthritis care, and there is no good evidence that their results can guide treatment for arthritis. Following restrictive diets based on them can mean missing out on important nutrients. If you think a food affects your symptoms, see our guide to foods that may trigger symptoms, which explains a safer way to test, ideally with a dietitian.
If you have genuine gut symptoms, such as ongoing diarrhoea, abdominal pain or bloating, see your GP. Tests for coeliac disease and inflammatory bowel disease are available on the NHS and are the right starting point.
A gut-friendly day
| Meal | Example |
|---|---|
| Breakfast | Porridge with banana and ground flaxseed |
| Lunch | Lentil and vegetable soup with wholemeal bread |
| Snack | Plain live yoghurt with berries |
| Evening meal | Chickpea, onion and vegetable curry with brown rice |
| Drinks | 6 to 8 cups or glasses of fluid, as the NHS suggests |
This pattern is very similar to an anti-inflammatory, Mediterranean-style diet, which has wider benefits for heart health and weight.
When to see a dietitian
Ask your GP about a referral to a registered dietitian if you have IBS, inflammatory bowel disease, coeliac disease, ongoing constipation or diarrhoea, or if you are thinking of following a restrictive diet such as a low-FODMAP diet. Dietitians are trained to guide these diets safely.
When to get medical help
See your GP if you have blood in your stools, black stools, ongoing diarrhoea, unexplained weight loss, persistent abdominal pain or a change in bowel habit lasting several weeks. If you take NSAIDs and get indigestion or stomach pain, speak to your GP or pharmacist. See your GP if your joints become swollen and painful after a stomach infection. Get same-day advice from your GP or NHS 111 if a joint suddenly becomes hot, swollen and very painful, especially with a fever, and call 999 if you are vomiting blood.
Frequently asked questions
Is gut health linked to arthritis?
Research shows links between gut bacteria and the immune system, and some gut infections can trigger reactive arthritis. But there is no good evidence yet that changing your gut bacteria treats arthritis.
Do probiotics help arthritis?
Arthritis UK says probiotics have not been shown to help. A review found small changes in some measures in rheumatoid arthritis, but the evidence is not strong enough to recommend them.
Is it safe to take probiotics with methotrexate or biologics?
The NHS advises people with a weakened immune system to talk to a doctor before taking probiotics. Ask your rheumatology team or pharmacist first.
Is leaky gut real?
Gut permeability is studied by researchers, but "leaky gut syndrome" as a cause of arthritis that can be cured with supplements is not supported by good evidence.
What is the best diet for gut health?
A varied diet with plenty of fibre from wholegrains, beans, lentils, fruit and vegetables, aiming for the NHS target of 30g of fibre a day.
Should I take a microbiome test?
There is no good evidence that home microbiome tests can guide arthritis treatment. If you have gut symptoms, see your GP for NHS tests.
Sources and further reading
- Arthritis UK: Eating well with arthritis (gut microbiome research)
- BDA: Probiotics food fact sheet
- NHS: Probiotics
- NHS: How to get more fibre into your diet
- Wu T et al. Effects of microecological regulators on rheumatoid arthritis: systematic review and meta-analysis. Nutrients 2023 (PMID 36904103)
- NHS: Reactive arthritis
- NHS: Taking methotrexate with other medicines and herbal supplements
Educational information for people in the United Kingdom — not personal medical or dietary advice. Food and supplements can interact with medicines, so check with your GP, pharmacist or rheumatology team before changing your diet significantly or starting a supplement, and ask for a referral to a registered dietitian for individual advice. Charity no. 1218461. Pending clinical and editorial review. If you feel very unwell, call 999 or go to A&E. For urgent advice, contact NHS 111.
Continue with related help
- The gut–joint connection — the science in more depth
- Plant-based diet review — fibre-rich eating and arthritis
- Anti-inflammatory diet — the overall eating pattern
- Arthritis diet myths — including 'leaky gut' claims
- Foods that may trigger symptoms — testing foods safely