A gut health supplement found in common vegetables may reduce knee arthritis pain in six weeks, study finds

A daily gut health supplement may do more than improve digestion. New research suggests it could also help reduce knee arthritis pain, improve strength, and even change how the body processes pain. Researchers found that inulin, a naturally occurring prebiotic fiber found in foods such as “chicory root, Jerusalem artichokes and other vegetables,” significantly reduced pain and improved grip strength in people with knee osteoarthritis after just six weeks.

The findings suggest that targeting gut bacteria could become a valuable addition to existing arthritis treatments, though the researchers stress that larger studies are still needed before the supplement can be recommended routinely.

What did the study investigate?

The study, published in Nutrients, titled "Effect of Prebiotic Supplementation With and Without Physiotherapy on Pain and Pain Sensitivity in People with Knee Osteoarthritis," was conducted by researchers from the University of Nottingham and collaborators.

It examined whether improving gut health through a prebiotic supplement could reduce pain associated with knee osteoarthritis, either alone or alongside physiotherapy.

The researchers recruited 117 adults with symptomatic knee osteoarthritis and randomly assigned them to one of four groups:

• Inulin supplementation
  
• Physiotherapy-supported exercise
  
• A combination of inulin and physiotherapy
  
• Placebo
  

Participants followed their assigned treatment for six weeks, after which researchers assessed changes in pain, physical function, pain sensitivity, and biological markers linked to gut health and inflammation.

The supplement reduced pain and improved strength

Compared with those receiving the placebo, participants taking inulin experienced:

• Reduced knee pain
  
• Improved grip strength
  
• Lower pain sensitivity
  
• Increased levels of GLP-1, a gut hormone linked to pain regulation and muscle function
  

Interestingly, while exercise also helped reduce knee pain, it did not improve grip strength or pain sensitivity to the same extent as the prebiotic supplement.

According to the researchers, the findings suggest that altering the gut microbiome may influence not only inflammation but also the nervous system's response to pain.

“This study raises the exciting possibility that a simple dietary change - adding a fiber supplement to your breakfast or yogurt - could meaningfully reduce pain and improve physical function." Afroditi Kouraki, lead author of the study said.

How can a gut supplement affect arthritis?

Unlike probiotics, which introduce beneficial bacteria into the digestive system, prebiotics serve as food for the beneficial bacteria already living in the gut. When gut microbes ferment inulin, they produce short-chain fatty acids, including butyrate, which are known to influence immune function, inflammation, and communication between the gut and the brain.

The researchers propose that these biological changes may partly explain why participants reported less pain and showed reduced pain sensitivity after supplementation. Higher GLP-1 levels were also associated with stronger grip strength, suggesting a possible connection between gut health, muscle function, and pain perception.

Participants found the supplement easier to stick with

The study also highlighted an important practical advantage. Only 3.6% of participants receiving the inulin supplement dropped out of the trial, compared with 21% of those assigned to physiotherapy-supported exercise.

Not a cure for arthritis

Despite the encouraging results, the authors caution against viewing inulin as a cure. The trial lasted only six weeks and involved a relatively small group of participants with knee osteoarthritis. The findings cannot yet be applied to other forms of arthritis, such as rheumatoid arthritis, and longer-term studies involving larger populations will be needed to confirm the benefits and determine the optimal dosage.