A six-week randomized trial of 117 adults found that the prebiotic fibre inulin reduced knee arthritis pain and pain sensitivity and improved grip strength, though researchers stress larger studies are needed.
Researchers led by the University of Nottingham report that a daily supplement of inulin, a prebiotic fibre found in foods such as chicory root and Jerusalem artichokes, reduced pain in people with knee osteoarthritis. The findings, published in the journal Nutrients, come from the INSPIRE trial, a six-week randomized controlled study of 117 adults. Participants were assigned to inulin alone, digitally supported physical therapy exercises alone, a combination of both, or a placebo. Those taking inulin reported significant reductions in pain, improved grip strength and lower sensitivity to pain.
Both inulin and physical therapy reduced knee pain on their own, but the supplement produced additional improvements in grip strength and pain sensitivity that were not seen with exercise alone. Adherence also differed: only 3.6% of the inulin-only group dropped out, compared with 21% of the physical-therapy-only group. Participants taking inulin showed higher levels of butyrate, a compound made when gut bacteria ferment fibre, and of the gut hormone GLP-1. Higher GLP-1 was associated with better grip strength, although the researchers note this does not establish that the hormone caused the improvement.
The team cautions that the trial was relatively small and lasted only six weeks, so larger studies with longer follow-up are needed to confirm whether the benefits last and to identify who is most likely to respond. The results do not suggest that fibre supplements should replace exercise or established arthritis treatments; rather, they point to a possible complementary approach. Lead author Dr Afroditi Kouraki said the findings raise the possibility that a simple dietary change could help, while senior author Professor Ana Valdes described a possible gut-muscle-pain axis that warrants further investigation. Knee osteoarthritis affects hundreds of millions of people worldwide, and anyone considering a supplement should first speak to a health professional.
