A simple daily fiber supplement may ease pain and strengthen muscles in people with knee osteoarthritis, according to a new clinical trial that challenges the conventional focus on exercise-based treatments.
Researchers at the University of Nottingham tested inulin, a natural prebiotic fiber derived from chicory root and Jerusalem artichokes, in a six-week randomized controlled trial of 117 adults with knee osteoarthritis. The supplement reduced pain independently, and participants who took it also showed measurably improved grip strength and lower sensitivity to pain signals. The findings appear in the journal Nutrients.
What made the results particularly striking was what happened to study dropouts. Only 3.6 percent of the inulin group quit, compared with 21 percent of participants assigned to a digital physiotherapy program. That difference hints at a fundamental challenge in treating osteoarthritis: telling patients to exercise is far harder to sustain than asking them to swallow a supplement.
Knee osteoarthritis affects hundreds of millions of people worldwide and is a leading cause of chronic pain and disability in older age. Most treatment relies on pain medications, which carry side effects, or on exercise regimens that patients struggle to maintain long-term.
"This study raises the exciting possibility that a simple dietary change, adding a fiber supplement to your breakfast or yogurt, could meaningfully reduce pain and improve physical function," said Dr. Afroditi Kouraki, lead author of the study and a researcher in the School of Medicine at the University of Nottingham.
The mechanism appears rooted in gut health. Inulin is a prebiotic, meaning it feeds beneficial bacteria in the digestive system. When those bacteria consume inulin, they produce short-chain fatty acids, particularly butyrate, a compound that influences inflammatory pathways and pain signals throughout the body.
Trial participants who received inulin had elevated levels of butyrate and also glucagon-like peptide-1, or GLP-1, a gut hormone linked to pain regulation and muscle health. The rise in GLP-1 correlated with stronger grip, suggesting a direct connection between gut bacteria and muscle function that researchers believe warrants deeper study.
The trial divided participants into four groups receiving inulin alone, digital physiotherapy-supported exercise alone, both treatments combined, or placebo. Both inulin and physiotherapy reduced knee pain on their own. But only the inulin group showed improvements in grip strength and pain sensitivity, measurements that reflect how the nervous system processes pain signals.
"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," Kouraki said. "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."
Senior author Professor Ana Valdes called the link between GLP-1 and grip strength "particularly intriguing" and flagged it as evidence of a broader gut-muscle-pain axis that could have implications beyond osteoarthritis, potentially shedding light on how gut health influences aging and physical resilience overall.
Author Jessica Williams: "A fiber supplement that cuts arthritis pain and has a dropout rate one-sixth that of exercise programs could genuinely shift how people manage this disease, if these results hold up in larger trials."
Comments