Inulin supplementation improves some inflammatory indices, clinical outcomes, and quality of life in rheumatoid arthritis patients.

The short version

This triple-blind randomised trial with 59 adults who have rheumatoid arthritis (RA) explored whether inulin, a fermentable plant fibre found in foods such as chicory, garlic and onions, can calm the inflammation and joint symptoms of the disease. RA is an autoimmune condition in which the immune system attacks the joints, and the researchers noted that long-term steroids and anti-inflammatory drugs carry real side effects. Because gut bacteria are altered in people with RA, they asked whether a prebiotic that feeds beneficial bacteria could help as an add-on. Researchers in Isfahan, Iran, enrolled 60 patients with active RA (59 were analysed). For 8 weeks, one group took a 10 g sachet of inulin with a main meal each day, and the other took identical-looking maltodextrin sachets, all alongside their usual medicines. Staff measured blood inflammation markers (CRP and ESR), counted tender and swollen joints out of 28, rated pain and morning stiffness on 0 to 100 scales, tested grip strength, and scored disease activity (DAS-28) and everyday function with the Health Assessment Questionnaire. Inflammation fell more with inulin: CRP dropped by 11.72 mg/L while it rose slightly with placebo (p = 0.02). Tender joints fell by 8.1 versus 2.9 (p = 0.002), swollen joints by 3.5 versus 1.8 (p = 0.04), and disease activity by 1.57 points versus 0.67 (p = 0.02). Daily function and morning stiffness improved (both p = 0.02) and grip strength rose by about 27 units versus 4 (p = 0.02). ESR improved within the inulin group, but the difference from placebo was not significant after adjustment (p = 0.13), and pain scores fell in both groups without a significant gap (p = 0.11). No side effects were reported. The authors treat the findings as promising but note they did not measure gut bacteria or gut-lining permeability, so the mechanism remains unconfirmed. The trial lasted only 8 weeks, tested one inulin dose, and did not assess how much inulin participants already ate. The authors call for larger studies with different doses and with cytokine, microbiome and permeability measures.

Key findings

• In this triple-blind trial, 59 adults with active rheumatoid arthritis (an autoimmune disease that inflames the joints) took 10 g/day of inulin, a fermentable plant fibre that acts as a prebiotic (food for gut bacteria), or a dummy powder for 8 weeks alongside their usual medicines.
• CRP, a blood marker of inflammation, fell 11.72 mg/L with inulin but rose 1.61 mg/L with placebo (adjusted p = 0.02), and the disease activity score (DAS-28) improved by 1.57 points versus 0.67.
• Tender joints dropped by 8.1 versus 2.9, swollen joints by 3.5 versus 1.8, and everyday function (HAQ), morning stiffness and grip strength also improved more with inulin (all p of 0.04 or lower).
• Pain intensity and ESR (another inflammation marker) did not differ significantly between groups, and no side effects were reported.
• The authors note the short 8-week duration, single dose and missing gut-microbiome data, and call for larger studies.

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