A Common Fiber Supplement May Help Ease Arthritis Pain

A daily fiber supplement eased knee arthritis pain in a small clinical trial, and researchers also saw an unexpected improvement in participants’ hand strength.

Adults who took inulin reported less knee pain and showed stronger handgrips after six weeks, according to researchers at the University of Nottingham. The renewed interest in the findings raises a practical question: could supporting gut bacteria help people remain active?

What Changed Over Six Weeks

The INSPIRE trial included 117 people who completed the study, with an average age of about 68. Researchers compared four approaches: 20 grams of inulin a day, digitally supported physiotherapy exercise, a combination of both, and a maltodextrin placebo.

Inulin on its own lowered pain by an adjusted 1.11 points more than placebo on a 0 to 10 scale. Exercise alone reduced pain by 1.55 points. The results do not show that one treatment was clearly better than the other.

“Inulin and PSE each produced meaningful pain reductions,” the authors wrote, adding that the treatments had “a moderate effect on both pain reduction and pain sensitisation.” Handgrip strength also improved, though that does not prove the supplement repaired knee cartilage or strengthened participants’ legs.

Why the Gut Link Matters

Inulin feeds gut bacteria. Participants who took it had higher levels of butyrate and the gut hormone GLP-1, and higher GLP-1 was associated with stronger grips.

“This could have implications not just for osteoarthritis, but for understanding how gut health influences ageing and physical resilience more broadly,” senior author Ana Valdes, PhD, said in the university’s announcement.

Still, the mechanism is not clear. The researchers warned that “these results should be considered exploratory.” GLP-1 testing was not planned in advance, and the association does not prove the hormone caused the strength gains.

The study was published earlier in the year, well before the recent coverage. Long-term benefits have not been established.

What to Consider Before Trying It

Digestive side effects are worth noting: 23 of 50 participants who completed an inulin-containing intervention reported mild gas or bloating. People with irritable bowel syndrome were excluded from the study.

Meanwhile, the NHS says: “Exercise is one of the most important treatments for people with osteoarthritis, whatever your age or level of fitness.”

NICE advises: “For all people with osteoarthritis, offer therapeutic exercise tailored to their needs (for example, local muscle strengthening, general aerobic fitness).”

The takeaway is simple: talk with a clinician about whether inulin belongs in your arthritis care plan, especially if you already have digestive symptoms, and keep up with exercise while the connection is studied further.