Inulin for Rheumatoid Arthritis: Study Shows Benefits for Inflammation, Disease Activity, and Quality of Life

Rheumatoid arthritis (RA) is an autoimmune disease in which some patients have dysbiosis of the intestinal microbiota. Prebiotics - dietary fiber that "feeds" beneficial bacteria - have long been considered a gentle addition to basic therapy. A new clinical trial in Scientific Reports tested whether inulin (a soluble prebiotic fiber) could affect inflammatory markers, clinical manifestations of RA, and quality of life.

Background of the study

Rheumatoid arthritis (RA) is a chronic autoimmune inflammation of the joints, in the development of which the gut-immune axis is increasingly playing a role. Dysbiosis has been repeatedly described in patients with RA: shifts in the composition of the microbiota, increased permeability of the intestinal barrier and associated immune signals that fuel systemic inflammation and disease activity. This layer of data has been consolidated in several modern reviews in recent years: changes in microbial communities are detected already at preclinical stages, and interventions that strengthen the barrier and increase the proportion of short-chain fatty acid (SCFA) producers are considered a promising addition to standard therapy.

Prebiotics—dietary fiber that “feeds” beneficial bacteria—have a special place in this logic. Fermentation of fiber in the colon produces SCFAs (acetate, propionate, butyrate), which reduce inflammatory signals, support regulatory T cells, influence the Th17/Treg balance, and strengthen the epithelial barrier. This is why dietary fiber and microbiota metabolites have been discussed as mild immunomodulators in autoimmune diseases, including RA. But until recently, most of the “positive” data on prebiotics in the context of RA came from animal experiments and small pilot studies, rather than full-scale clinical trials.

Inulin is one of the most studied prebiotics (fructan from chicory, Jerusalem artichoke, etc.). In arthritis models, it shifted the microbiota to the "bifid side", increased the output of butyrate and weakened inflammation, but in people with RA, there was practically no convincing randomized data. In fact, the authors of the new work in Scientific Reports themselves note: clinical evidence of the benefits of isolated inulin supplementation in RA has not yet been published; the effect was described mainly in mice. This is the gap that their randomized, triple-blind study closes.

Thus, the clinical logic is simple: if RA is associated with disturbances in the microbiota and barrier function, and SCFA and especially butyrate demonstrate immunoregulatory properties, then prebiotic support (in particular, with inulin) can become an adjuvant strategy to basic therapy - with an eye to reducing systemic inflammation and disease activity and improving well-being. The new trial tests this hypothesis in patients, rather than in models, and is therefore important for assessing the real clinical value of prebiotics in RA.

Design: Who, How Much and How

This was a randomised, triple-blind, parallel study of 8 weeks duration. 60 adults with active RA (DAS-28 > 3.2) were allocated to receive inulin 10 g/day or placebo (maltodextrin) in addition to their usual prescriptions. The inulin type was a high-performance, highly polymerised inulin (Frutafit® TEX). Participants were reminded to take the medication and asked not to change their diet/activity; records were collected and included in the analysis. The study is registered with IRCT (IRCT20230506058098N1). No adverse effects were reported.

What was measured?

• Inflammation: C-reactive protein (CRP), erythrocyte sedimentation rate (ESR).
• Clinical: number of swollen and painful joints, morning stiffness (VAS), grip strength (blood pressure cuff), pain (VAS), disease activity DAS-28.
• Quality of life/function: HAQ questionnaire.

Main results (after adjustments for baseline values and diet)

Both groups improved on several measures by week 8 (time and treatment effects), but inulin showed superiority over placebo on a number of critical metrics:

• CRP: significant between-group reduction in favor of inulin (p = 0.02 after all covariates).
• ESR: decreased within the inulin group, but the between-group difference became non-significant after accounting for energy and total fiber (p = 0.13).
• Number of painful and swollen joints: greater reduction with inulin (significant after adjustments).
• DAS-28: decreased in both groups, but more so in inulin (after adjustments p = 0.02).
• HAQ (function/quality of life) and morning stiffness: significantly improved only in the inulin group; between-group difference was significant.
• Grip strength: increased only with inulin; significant difference between groups (p=0.02 after covariates).
• Pain (VAS): no significant advantage over placebo was found (after all adjustments p = 0.11).

Bottom line: systemic inflammation (CRP), disease activity (DAS-28), functional status (HAQ), morning stiffness and grip strength improved significantly in those taking inulin; pain and ESR - without a clear between-group benefit.

How it can work

Inulin and related fructans are fermentable fibers that increase the proportion of bifidobacteria and lactobacilli, and their metabolites (short-chain fatty acids) support the intestinal barrier and modulate the immune response. The effect is usually expected at doses of 5-10 g / day, and tolerance up to 20 g / day in clinical studies is good. Here, 10 g / day for 8 weeks was chosen - a sufficient period for a moderate "shift" in the microbiota with a minimum of gastrointestinal side effects.

What does this mean for practice?

• Inulin - not instead of DMARDs, but together with them. The study was conducted against the background of standard therapy; the prebiotic is considered as an adjuvant to treatment, not a replacement for it.
• Potentially useful for: patients with active RA, for whom CRP, DAS-28, morning stiffness and function (HAQ, grip strength) are important. No separate effect on pain should be expected.
• What regimen was used: 10 g inulin per day, 8 weeks, no reported side effects in this study. Technically, it is a dietary supplement; choose with your doctor based on tolerance and overall diet.

Limitations - Important to understand before jumping to conclusions

This is a single-center trial, n=60, 8-week duration. There were small differences in the baseline diet between the groups (e.g. selenium and carbohydrates), which the authors took into account statistically; some results (ESR) “lost” significance after full adjustment. The study did not measure the microbiota directly - the mechanism of the effect remains hypothetical. Longer and larger RCTs with microbiome profiling and stratification by treatment are needed.

Reference: Where does inulin “live” in food?

Inulin-type fructans are found in chicory and Jerusalem artichoke, and are also found in garlic, onions, asparagus, artichokes, bananas, wheat, and soy; these are the foods most often mentioned in dietary recommendations to “feed” beneficial bacteria. Clinical protocols use purified powder forms to precisely specify the dose.

Conclusion

Inulin (10 g/day, 8 weeks) in patients with active RA reduced CRP and disease activity, improved function and morning stiffness, but was not superior to placebo for pain and ESR when tightly adjusted. This is a cautious but encouraging argument for prebiotics as adjuvants to standard RA therapy - adjusted for the size and duration of the study.

Source: Tabatabaeyan A. et al. Inulin supplementation improves some inflammatory indicators, clinical outcomes, and quality of life in rheumatoid arthritis patients. Scientific Reports (21 August 2025). DOI: https://doi.org/10.1038/s41598-025-16611-3