A daily prebiotic fiber supplement significantly reduced knee osteoarthritis pain, improved grip strength, and lowered pain sensitivity in a six-week clinical trial led by the University of Nottingham. Published in March 2026, the INSPIRE trial tested inulin on 117 adults, revealing a remarkably low dropout rate compared to standard physiotherapy programs.
For millions of older adults managing chronic joint pain, daily life often involves balancing the risks of long-term medication use with the physical demands of exercise regimens. A new clinical trial published in the journal Nutrients points toward an unexpected source of relief: the human digestive system. Researchers found that a daily dose of inulin—a natural dietary fiber found in chicory root, Jerusalem artichokes, and other vegetables—not only eased aching knees but also altered biological markers linked to muscle function and nervous system pain processing, according to HealthDay reporting.
The INSPIRE Clinical Trial Design and Results
Investigators screened 721 individuals before randomizing 136 participants, with 117 completing both baseline and follow-up assessments. The participants had an average age of 67.5 years and an average body mass index of 29.5, with women making up 58.12% of the group.
- Inulin supplement alone (taking 20 grams a day mixed into cereal, smoothies, yogurt, or drinks)
- Digital physiotherapy-supported exercise (PSE) alone, delivered via the Joint Academy platform
- Both inulin and physiotherapy combined
- A placebo group receiving 10 grams a day of maltodextrin with usual care
Both inulin and physiotherapy reduced knee pain independently when compared against the placebo.
Gut Health Mechanisms and the GLP-1 Connection
While both interventions successfully managed pain, they did not operate through identical biological pathways. Physiotherapy improved physical function measures such as squatting and walking ability, whereas the fiber supplement produced distinct systemic changes.
Laboratory analyses revealed that inulin consumption nourished beneficial gut bacteria, leading to higher levels of short-chain fatty acids, particularly butyrate. Butyrate is a compound known to influence inflammation and pain pathways throughout the body.
“The link we observed between GLP-1 and grip strength is particularly intriguing and points to a broader gut-muscle-pain axis that warrants further investigation. This could have implications not just for osteoarthritis, but for understanding how gut health influences ageing and physical resilience more broadly.”
Professor Ana Valdes, senior author and professor of medicine at the University of Nottingham
Adherence Rates and Public Health Implications
Beyond clinical score changes, the trial revealed a stark contrast in participant adherence. Only 3.6% of the participants assigned to the inulin supplement dropped out of the study, compared to a 21% dropout rate among those assigned to the digital physiotherapy exercise program. For patients who remained in the study, adherence averaged 84% for physiotherapy and 88% for inulin, but the sheer retention gap underscores how easily a dietary addition fits into daily routines compared to structured exercise programs.
“Our findings suggest that targeting gut health with a prebiotic supplement is a safe, well-tolerated, and effective way to reduce pain in people with knee osteoarthritis. The very low dropout rate compared to the exercise group is also encouraging from a public health perspective — people were able to fit this supplement easily into their daily lives.”
Dr. Afroditi Kouraki, lead author from the School of Medicine at the University of Nottingham
Charitable organizations and researchers emphasize that these findings represent an encouraging step forward in understanding the multifactorial nature of arthritis.