Taking a simple fiber pill every day might help people with knee arthritis feel less pain and move more easily. In a new study, those who took the fiber also got stronger hand grips and were less sensitive to pain. Very few people stopped taking the pill, while many stopped the online exercise program.
Scientists at the University of Nottingham ran the INSPIRE trial. They tested inulin, a natural fiber found in foods like chicory root and Jerusalem artichokes. The participants who ate inulin each day reported noticeably less knee pain.
The results were published in the journal Nutrients. They suggest that looking after the gut could be a fresh way to treat a common, disabling problem that many older adults face.
A Simpler Way to Treat Knee Arthritis
Millions of people around the world live with knee arthritis, which often leads to chronic pain and limits daily activities. Traditional treatments include pain medicines that can cause side effects, or long‑term exercise plans that many find hard to keep up with.
How Fiber May Change Pain
The gut is home to trillions of tiny bacteria that affect many parts of our health, including how we feel pain. Inulin is a “prebiotic,” meaning it feeds the good bacteria in the gut.
When these bacteria break down inulin, they produce short‑chain fatty acids. One important one is butyrate, which can calm inflammation and influence pain pathways throughout the body.
People who took inulin showed higher levels of both butyrate and a hormone called GLP‑1. GLP‑1 helps regulate pain and supports muscle health. The rise in GLP‑1 was also linked to better grip strength, hinting at a possible link between gut health and muscle function.
Fiber and Exercise Both Cut Pain
The six‑week trial included 117 adults with knee arthritis. They were split into four groups: inulin only, a digital physiotherapy exercise program only, both together, or a placebo.
Both the fiber pill and the exercise program reduced knee pain on their own. However, only the fiber group also showed stronger hand grips and less sensitivity to pain, which reflects how the nervous system processes uncomfortable signals.
The fiber group had a much lower dropout rate. Only 3.6 % of participants stopped taking the supplement, compared with 21 % of those in the exercise group. This suggests that adding a simple pill to a daily routine may be easier for many people than committing to regular online workouts.
Dr. Kouraki said, "Targeting gut health with a prebiotic supplement is safe, well‑tolerated, and can effectively lower pain for people with knee arthritis. The very low dropout rate shows how easy it is to fit this into daily life."
A Possible Gut‑Muscle‑Pain Link
Professor Lucy Donaldson, Director of Research at Arthritis UK, explained, "Arthritis pain can seriously affect quality of life. Our recent survey found that six in ten people live with constant pain. Researchers are now looking at how the gut microbiome influences pain. This early research shows that diet and physiotherapy can help in different ways. We know that a balanced diet with plenty of fiber and regular movement matters, and we support studies that explore how they work together for arthritis sufferers."