Effect of Prebiotic Supplementation With and Without Physiotherapy on Pain and Pain Sensitivity in People with Knee Osteoarthritis.

Inulin supplementation significantly reduced knee OA pain compared to placebo.

• Baseline-adjusted between-group mean difference Δ = -1.11 [95%CI -2.18, -0.04], p = 0.045
• Participants received 20 g/day inulin for 6 weeks
• Pain was measured using the Numerical Rating Scale (NRS)
• Baseline mean NRS pain score was 3.96 ± 2.67

Physiotherapy-supported exercise (PSE) significantly reduced knee OA pain compared to placebo.

• Baseline-adjusted between-group mean difference Δ = -1.55 [95%CI -2.52, -0.58], p = 0.002
• PSE was delivered via digital platform (Joint Academy™) over 6 weeks
• Pain was measured using the Numerical Rating Scale (NRS)
• No synergistic effect was observed when inulin and PSE were combined

There was no synergistic interaction between inulin supplementation and physiotherapy-supported exercise on pain outcomes.

• The study used a 2×2 factorial RCT design with four arms: inulin alone, PSE alone, inulin+PSE, and maltodextrin placebo
• The study was explicitly noted as not powered to detect synergistic interaction
• 117 community-dwelling adults with knee OA completed the trial

PSE improved physical function measures including timed up and go (TUG) and 30-second sit-to-stand (30-CST), while inulin did not.

• PSE improved TUG performance (p = 0.02)
• PSE improved 30-CST performance (p = 0.0004)
• These functional improvements were not observed with inulin supplementation

Inulin supplementation improved grip strength, pressure pain thresholds, and temporal summation compared to placebo.

• Inulin improved grip strength (p = 0.002)
• Inulin improved pressure pain thresholds (p = 0.009)
• Inulin improved temporal summation (p = 0.025)
• These pain sensitivity improvements were not observed with PSE

Inulin supplementation had a significantly lower dropout rate compared to PSE.

• Inulin dropout rate was 3.6%
• PSE dropout rate was 21%
• The difference in dropout rates was statistically significant (p < 0.01)

Only inulin supplementation increased serum short-chain fatty acid butyrate and glucagon-like peptide-1 (GLP-1).

• Inulin increased butyrate (p = 0.0248)
• Inulin increased GLP-1 (p = 0.0109)
• PSE did not produce these biochemical changes
• Higher GLP-1 was associated with improved grip strength, suggesting a gut-muscle link

The study enrolled 117 community-dwelling adults with knee osteoarthritis across four treatment arms.

• 58.1% of participants were female
• Mean age was 67.5 ± 9.4 years
• Mean BMI was 29.5 ± 5.3 kg/m²
• Mean baseline NRS pain score was 3.96 ± 2.67
• The trial duration was 6 weeks

Emerging evidence links the gut microbiome to chronic pain processing, providing a rationale for prebiotic intervention in osteoarthritis.

• Inulin, a prebiotic fibre, modulates the gut microbiome
• Physiotherapy-supported exercise improves pain and function in knee OA
• The study measured serum short-chain fatty acids (SCFAs) and GLP-1 as potential mechanistic biomarkers
• Quantitative sensory testing was included as a secondary outcome to assess central pain sensitization