A daily dose of inulin, a prebiotic fibre found in chicory root and other vegetables, significantly reduced knee pain and improved grip strength in adults with knee osteoarthritis, according to a six-week clinical trial led by University of Nottingham researchers and published in the journal Nutrients.
Knee osteoarthritis affects hundreds of millions of people worldwide and is a major cause of chronic pain and disability, especially among older adults. The condition develops as the tissues within the knee joint, including the cartilage that cushions the ends of bones, gradually deteriorate, leading to pain, stiffness, swelling, and difficulty with everyday activities such as walking or climbing stairs.
In the INSPIRE trial, 117 adults with knee osteoarthritis were assigned to one of four groups: a daily inulin supplement alone, digitally supported physical therapy exercises alone, a combination of the two, or a placebo. Both inulin and physical therapy independently reduced knee pain, the researchers found, but only the supplement produced additional improvements in grip strength and reduced sensitivity to pain.
Participants appeared to find the supplement considerably easier to sustain than exercise. Only 3.6% of those assigned to inulin alone dropped out of the study, compared with 21% of those assigned to physical therapy alone.
Unlike many nutrients, inulin is not broken down by digestive enzymes in the small intestine. It passes into the large intestine, where beneficial bacteria can use it as food, fermenting it to produce short-chain fatty acids including butyrate. Participants taking inulin showed increased butyrate levels and higher levels of glucagon-like peptide-1 (GLP-1), a gut hormone that helps regulate blood sugar and appetite and has been linked to pain regulation and muscle health. Higher GLP-1 levels were associated with better grip strength, although the study does not establish that GLP-1 caused the improvement. GLP-1 is the hormone targeted by medications such as Ozempic and Wegovy, but the supplement was not a GLP-1 medication.
Dr. Afroditi Kouraki, lead author of the study from the School of Medicine at the University of Nottingham, said: "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."
She added: "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."
Senior author Professor Ana Valdes said: "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 aging and physical resilience more broadly."
The findings are promising, but the trial was relatively small and lasted only six weeks. Larger studies with longer follow-up periods will be needed to establish whether the benefits persist, identify which patients are most likely to respond, and clarify the biological mechanisms responsible. The results also do not suggest that fibre supplements should replace exercise or other established arthritis treatments.
Analysis
Why This Matters
- Knee osteoarthritis affects hundreds of millions of people worldwide and is a major cause of chronic pain and disability, particularly for older adults; a simple daily supplement could offer an additional, easily sustained way to manage symptoms.
- The sharply lower dropout rate in the inulin group compared with the exercise group suggests adherence may be a practical advantage of a supplement-based approach.
- The trial adds evidence for a gut-muscle-pain connection, with potential implications for how gut health influences aging and physical resilience.
Background
The gut microbiome, the community of microorganisms living in the digestive tract, is increasingly understood to influence much more than digestion. Microbes interact with the immune system, produce biologically active compounds, and may affect how the nervous system responds to pain. Inulin is classified as a prebiotic because it nourishes beneficial gut bacteria rather than supplying living microorganisms directly, as probiotics do. When bacteria ferment inulin, they produce short-chain fatty acids such as butyrate, which supports the intestinal lining and can influence inflammation and biological pathways involved in pain.
Conventional treatment for knee osteoarthritis focuses on reducing symptoms and maintaining mobility. Pain medications can provide relief but may cause unwanted side effects, while physical therapy and regular exercise can improve joint function, though keeping up with an exercise program can be difficult for people already struggling with persistent pain.
Key Perspectives
Dr. Afroditi Kouraki, lead author: says the 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, with the low dropout rate compared with the exercise group encouraging from a public health perspective.
Professor Ana Valdes, senior author: says the link between GLP-1 and grip strength is particularly intriguing and points to a broader gut-muscle-pain axis that warrants further investigation, with implications not just for osteoarthritis but for how gut health influences aging and physical resilience.
What to Watch
- Whether larger studies with longer follow-up confirm the benefits persist and identify which patients are most likely to respond.
- Further research into the biological mechanisms, particularly the relationship between GLP-1, butyrate and muscle strength.
- Whether the results shape clinical guidance on using prebiotic supplements alongside, rather than in place of, exercise and other established treatments.
Checked
12 claims in this story checked against 1 source: 11 supported.
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- SupportedThe headline says a daily fibre supplement eased knee arthritis pain and improved grip strength in a trial.Latest Science News -- ScienceDaily: “people with knee osteoarthritis (OA) who took a prebiotic fiber called inulin experienced significant reductions in pain, improved grip strength, and decreased sensitivity to pain.”
- SupportedThe summary says the University of Nottingham study points to a connection between gut health, muscles and pain.Latest Science News -- ScienceDaily: “The association between GLP-1 and grip strength raises the possibility of a broader biological relationship connecting gut health with physical performance and resilience as people age.”
- SupportedThe trial found that adults taking inulin had significant reductions in knee pain and improved grip strength.Latest Science News -- ScienceDaily: “people with knee osteoarthritis (OA) who took a prebiotic fiber called inulin experienced significant reductions in pain, improved grip strength, and decreased sensitivity to pain.”
- SupportedThe six-week trial was led by University of Nottingham researchers and published in Nutrients.Latest Science News -- ScienceDaily: “In a clinical trial led by researchers at the University of Nottingham”
- SupportedThe INSPIRE trial assigned 117 adults with knee osteoarthritis to one of four groups: inulin, physical therapy, both, or placebo.Latest Science News -- ScienceDaily: “a six-week randomized controlled study involving 117 adults with knee osteoarthritis. Participants were assigned to one of four treatment groups: a daily inulin supplement alone, digitally supported physical therapy exercises (PSE) alone, a combination of inulin and physical therapy, or a placebo.”
- Partly supportedBoth inulin and physical therapy independently reduced knee pain, while only the supplement produced additional improvements in grip strength and pain sensitivity.Latest Science News -- ScienceDaily: “Both inulin and physical therapy independently reduced knee pain, indicating that each approach provided meaningful symptom relief. However, the supplement produced additional improvements that were not observed with physical therapy alone.”
- SupportedDropout was 3.6% in the inulin-only group and 21% in the physical-therapy-only group.Latest Science News -- ScienceDaily: “Only 3.6% of the inulin-only group dropped out, compared with 21% of the physical therapy-only group.”
- SupportedParticipants appeared to find the supplement considerably easier to sustain than exercise.Latest Science News -- ScienceDaily: “The supplement also appeared to be considerably easier for participants to stick with than a digital physical therapy program.”
- SupportedDr. Afroditi Kouraki said the study raised the possibility that adding a fibre supplement to breakfast or yogurt could reduce pain and improve physical function.Latest Science News -- ScienceDaily: “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,”
- SupportedKouraki said a prebiotic supplement was a safe, well-tolerated and effective way to reduce knee osteoarthritis pain, and that the low dropout rate was encouraging.Latest Science News -- ScienceDaily: “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.”
- SupportedProfessor Ana Valdes said the GLP-1 and grip-strength link pointed to a gut-muscle-pain axis warranting further investigation.Latest Science News -- ScienceDaily: “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.”
- SupportedThe trial lasted six weeks, and larger studies with longer follow-up are needed to establish whether benefits persist and clarify mechanisms.Latest Science News -- ScienceDaily: “The findings are promising, but the trial was relatively small and lasted only six weeks. Larger studies with longer follow-up periods will be needed to establish whether the benefits persist”