A prebiotic fibre supplement may ease arthritis pain and improve grip strength in people with knee osteoarthritis, a study suggests.
The daily supplement, made from inulin, a dietary fibre found in chicory root, Jerusalem artichokes and other vegetables, also lowered pain sensitivity and saw fewer people drop out than a digital physiotherapy programme tested alongside it.
Dr Afroditi Kouraki, lead author of the study from the University of Nottingham, said: ‘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.’
Osteoarthritis of the knee, a wear-and-tear joint condition, affects hundreds of millions of people worldwide and is a leading cause of pain and disability, particularly in older adults.
Current treatments rely heavily on pain medication, which can cause side effects, or exercise programmes, which many patients find hard to maintain.
The INSPIRE trial, led by researchers at the University of Nottingham, involved 117 adults with knee osteoarthritis and tested four groups: inulin alone, digital physiotherapy-supported exercise alone, a combination of both, and a placebo. Both inulin and physiotherapy independently reduced knee pain.
However, inulin alone improved grip strength and reduced pain sensitivity, measures linked to how the nervous system processes pain, while physiotherapy did not.
The dropout rate for those taking the supplement was just 3.6 per cent, compared with 21 per cent for the physiotherapy group, suggesting a daily supplement may be easier for people to stick with than an exercise programme.
Inulin works as a prebiotic, meaning it feeds beneficial bacteria in the gut.
This leads to the production of compounds called short-chain fatty acids, particularly butyrate, which can affect inflammation and pain pathways throughout the body.
Participants taking inulin also showed increased levels of both butyrate and GLP-1, a gut hormone linked to pain regulation and muscle health.
Higher GLP-1 levels were associated with improved grip strength, pointing to a possible gut-muscle connection.
Senior author Professor Ana Valdes added: ‘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 Lucy Donaldson, director of research at Arthritis UK, said: “The pain of arthritis can severely impact quality of life. Our recent lived experience survey showed that six in ten people are living in pain most or all of the time due to their arthritis.
“Researchers are starting to explore the role of the gut microbiome in our experience of pain.
“This exciting preliminary research highlights how diet and physiotherapy can act in different ways to have benefits for people with arthritis.
“We know a variety and balance of healthy foods, including fibre, and regular physical activity matter, and we’re glad to be supporting research that explores how they work to help people with arthritis.”
