Daily fiber supplement may ease knee arthritis pain

A daily fiber supplement eased knee arthritis pain in a small clinical trial, suggesting that gut bacteria may open up a new path for pain relief. People who took the supplement also showed better grip strength and reduced sensitivity to pain.

The findings are important because osteoarthritis can make everyday movement difficult, and scientists are searching for more ways to control its symptoms. Rather than aiming to rebuild damaged cartilage, the study examined a possible link between the digestive system and pain.

Researchers at the University of Nottingham studied a fiber called inulin in a six-week randomized trial involving 117 adults. The results, published in Nutrients, compared inulin supplementation, exercise-based physiotherapy, the two combined and a placebo supplement without inulin.

Inulin is a prebiotic, which means it feeds certain bacteria in the gut. Those bacteria can convert fiber into substances that affect processes elsewhere in the body, making them a growing focus in pain research.

Participants given inulin took 20 grams a day. Those in the physiotherapy groups followed a digital exercise program, while the placebo supplement contained maltodextrin, a carbohydrate used as a comparison treatment.

The team assessed knee pain as well as mobility, strength and responses to pressure and repeated painful stimulation. Blood markers were also analyzed to look for possible connections between changes in gut-related chemistry and physical outcomes.

Compared with placebo, inulin improved pain scores by about 1.1 points on the study’s rating scale. Exercise supported by physiotherapy improved scores by about 1.6 points, showing that both approaches offered benefits over the short follow-up period.

The exercise program improved measures of movement and leg function. Inulin, meanwhile, was linked to stronger grip and changes in pain sensitivity, suggesting that the two treatments may affect different aspects of health.

Only inulin increased blood levels of butyrate, a compound produced when gut bacteria break down fiber, and GLP-1, a hormone involved in the body’s response to food. Higher GLP-1 levels were associated with better grip strength.

These results point to a possible connection between gut activity and muscle function, but they do not prove that either blood change directly caused the improvements. The study also did not show that combining inulin with exercise provided any extra benefit beyond the two approaches separately.

The trial was small and brief, and the pain result for inulin had a wide margin of uncertainty. It cannot show whether the benefits last for months or years, or whether supplementation affects the underlying course of joint damage.

Even so, the findings offer a reason to study the gut’s role in arthritis symptoms more closely. Larger trials could determine whether a simple dietary supplement can become a useful addition to treatments that already help people move and function better.

Source: University of Nottingham.