A new study has found that a prebiotic fibre supplement can reduce pain and improve strength in people with knee osteoarthritis (OA). It also lowered pain sensitivity and had far fewer dropouts than a digital physiotherapy programme. The research, called the INSPIRE clinical trial, was led by experts at the University of Nottingham. Participants took a daily supplement of inulin, a natural fibre found in chicory roots, Jerusalem artichokes, and some vegetables. It helped reduce pain in people with OA.
The study found that inulin helped reduce knee pain in adults with osteoarthritis. The improvement was clear and meaningful for many participants. The results are published in the journal Nutrients, suggest that better gut health may help manage osteoarthritis in a new and simple way. The findings could offer an additional option alongside current treatments.
Knee OA affects millions of people worldwide. It is a major cause of pain and disability, especially for older adults. Current treatments rely on pain medicines, which can cause side effects, or on exercise programs, which some patients find hard to follow.
Dr Afroditi Kouraki, lead author from the School of Medicine at the University of Nottingham, said a simple dietary change could make a big difference. “Adding a fibre supplement to breakfast or yoghurt may help reduce pain and improve function,” she said.
The gut microbiome, which is made up of trillions of bacteria in our digestive system, affects overall health and pain. Inulin acts as a prebiotic. It helps feed the good bacteria in the gut. These bacteria make substances called short-chain fatty acids. One of them is called butyrate. Butyrate can lower inflammation. It can also affect how the body feels pain.
In the study, participants taking inulin had higher levels of butyrate and a gut hormone called glucagon-like peptide-1 (GLP-1). GLP-1 is linked to pain control and muscle health. Participants with higher GLP-1 also had stronger grip strength. This shows a possible connection between gut health, muscles, and pain.
The INSPIRE trial lasted six weeks and included 117 adults with knee OA. The participants were divided into four groups. One group took only inulin. One followed digital physiotherapy-supported exercise (PSE) only. One group combined inulin and physiotherapy. The last group took a placebo.
Both inulin and physiotherapy reduced knee pain. But only inulin improved grip strength and lowered pain sensitivity. Physiotherapy did not have the same effect.
Dropout rates were completely unique. Only 3.6% of the inulin group stopped the study. Meanwhile, 21% of the physiotherapy group dropped out. This shows that a daily supplement may be easier to follow than a regular exercise programme. Dr Kouraki said targeting gut health with a prebiotic is safe, effective, and well-tolerated. She also highlighted the low dropout rate, showing that people could easily take the supplement in daily life.
Professor Ana Valdes, senior author, said the link between GLP-1 (glucagon-like peptide-1) and grip strength is very interesting. She called it a possible “gut-muscle-pain axis” and said it deserves more research. This could help with osteoarthritis and also improve understanding of ageing and physical health.
Professor Lucy Donaldson from Arthritis UK said that arthritis pain can seriously reduce a person’s quality of life. Around six out of ten people with arthritis live with pain most or all of the time. She explained that both diet and physiotherapy can help in different ways. Eating a balanced diet with plenty of fibre and staying active with regular exercise are both very important for managing symptoms.
The INSPIRE trial showed that taking a simple fibre supplement every day could reduce pain, improve strength, and make daily life easier for people with knee osteoarthritis. Combined with exercise, supporting gut health may be a practical and natural way to manage this common and long-term condition. This approach could give many people better comfort and more independence in their everyday life.
