A randomized clinical trial led by researchers at the University of Nottingham found that a daily prebiotic fiber supplement containing inulin may help reduce pain and improve certain aspects of physical function in adults with knee osteoarthritis. The six-week INSPIRE study enrolled 117 participants, who were assigned to receive either inulin alone, digital physiotherapy-supported exercise, both interventions together, or a placebo. Researchers reported that both inulin supplementation and physiotherapy independently reduced knee pain. However, participants taking inulin also experienced improvements in grip strength and reduced pain sensitivity, outcomes that were not observed in the physiotherapy-only group. The researchers suggest these findings may indicate broader effects on the nervous system and muscle function. The study also measured biological markers associated with gut health. Participants receiving inulin showed increased levels of butyrate, a short-chain fatty acid produced by beneficial gut bacteria, as well as higher concentrations of glucagon-like peptide-1 (GLP-1), a hormone linked to pain regulation and muscle health. Higher GLP-1 levels were associated with stronger grip strength, supporting the hypothesis of a gut-muscle-pain connection that warrants further investigation. Another notable finding was adherence to treatment. Only 3.6% of participants in the inulin group discontinued the study, compared with 21% in the physiotherapy group, suggesting that taking a daily supplement may be easier for many patients to maintain than following an exercise program. Although the findings are encouraging, the authors emphasize that this was a relatively short six-week study and that larger, longer-term clinical trials are needed to confirm the benefits and determine the long-term role of prebiotic fiber supplementation in managing knee osteoarthritis.

Prebiotic fiber inulin reduced pain, improved grip strength, and lowered pain sensitivity in people with knee osteoarthritis. ...