Daily Fiber Supplement Reduces Knee Osteoarthritis Pain as Effectively as Exercise in Six-Week Trial

Jul 25, 2026

A six-week clinical trial by the University of Nottingham reveals that a daily prebiotic fiber supplement, inulin, reduces knee osteoarthritis pain as effectively as exercise. Inulin lowered pain scores by 1.11 points and improved grip strength, while exercise lowered pain by 1.55 points. Notably, the inulin group had a 3.6% dropout rate compared to 21% for exercise. Inulin also reduced pain sensitivity and raised butyrate and GLP-1 levels, suggesting a gut-muscle-pain connection.

INSPIRE trial design

▪The INSPIRE trial randomly assigned participants to four groups: 20 grams of daily inulin, digital physiotherapy-supported exercise, a combination of both, or a placebo.
▪Participants in the INSPIRE trial had an average age of 67.5 years, 58 percent were women, and the average baseline pain score was 4 out of 10.
▪The INSPIRE clinical trial, led by University of Nottingham researchers, evaluated 117 adults with symptomatic knee osteoarthritis over a six-week period.

Inulin pain reduction outcomes

▪Inulin supplementation lowered knee pain scores by an average of 1.11 points on a 10-point scale.
▪Daily inulin supplementation significantly improved participant grip strength compared to a placebo.
▪Daily inulin supplementation significantly reduced knee pain compared to a placebo over the six-week trial.

Exercise pain reduction outcomes

▪Digital physiotherapy-supported exercise significantly reduced knee pain compared to a placebo, lowering pain scores by an average of 1.55 points.
▪Physiotherapy-supported exercise improved physical movement tests, specifically the timed up and go and the 30-second sit-to-stand tests.

Pain sensitivity mechanisms

▪Inulin supplementation reduced temporal summation, which reflects how much the nervous system amplifies pain signals.
▪Inulin supplementation raised blood levels of butyrate and glucagon-like peptide-1, a gut hormone linked to pain regulation and muscle function.
▪Inulin supplementation lowered pain sensitivity and raised pressure pain thresholds.
▪Increased glucagon-like peptide-1 levels in the inulin group were associated with stronger grip strength.

Treatment adherence rates

▪Only 3.6% of participants receiving the inulin supplement dropped out of the trial.
▪In contrast, 21% of participants assigned to the physiotherapy-supported exercise program dropped out of the trial.

Dosing safety considerations

▪The INSPIRE trial findings are limited by a six-week duration and cannot yet be applied to other forms of arthritis.
▪Consuming 20 grams of inulin daily can cause common side effects such as gas and bloating.
▪Experts recommend starting with a few grams of inulin daily and increasing the dose gradually over two to three weeks.