The short answer: possibly, but the evidence is early. In a 2026 University of Nottingham trial of 117 adults with knee osteoarthritis, 20 grams a day of a prebiotic fiber called inulin lowered pain by about 1 point on a 10-point scale after six weeks, compared with a placebo. Physiotherapy-led exercise lowered it by about 1.5 points. Fiber may be a useful add-on, but it doesn’t replace exercise, and nearly half the people taking it had minor wind or bloating.
The trial got attention because it looks at arthritis from an unusual angle: your gut. Pain, it suggests, may be partly shaped by what happens in your digestive system.
What did the trial find?
Researchers split people with knee osteoarthritis into four groups for six weeks. Their average age was 67, and their pain started at about 4 out of 10.
| Group | Daily plan | Pain change vs placebo |
|---|---|---|
| Inulin | 20 g inulin powder | 1.11 points lower |
| Exercise | Digital physiotherapy-led exercise program | 1.55 points lower |
| Both | Inulin and exercise | No extra benefit shown from combining them |
| Placebo | 10 g maltodextrin | Comparison group |
Inulin also improved grip strength and made people less sensitive to pain. Exercise improved leg function measures that inulin didn’t, such as standing up from a chair and walking.
Staying with it was the surprise. Only 3.6% of the inulin group dropped out, against 21% of the exercise group.
How good is this evidence?
It’s promising but not settled, and the headlines ran ahead of it:
- The pain result was only just significant. The range around it ran from a 2.18-point drop to a 0.04-point drop, so the true effect could be small.
- It was six weeks. Nobody knows yet if the benefit lasts.
- The groups were small. It wasn’t large enough to show whether fiber and exercise work better together, so the “no extra benefit” result isn’t firm either.
- It tested knees only. It doesn’t tell us anything about hip or back arthritis.
- It tested one fiber. Inulin isn’t the same as psyllium or oats, and those weren’t studied here.
How could fiber ease joint pain?
We don’t know for sure. Inulin isn’t digested in the small intestine. It travels to the large intestine, where gut bacteria feed on it. In the trial, people taking it had higher levels of GLP-1, a gut hormone, and higher GLP-1 went along with better grip strength. The authors call this exploratory, so it’s a clue and not an explanation. It also doesn’t mean inulin works like the GLP-1 weight-loss drugs.
Should you try inulin for knee pain?
It may be worth a try if your doctor has confirmed osteoarthritis and your stomach tolerates fiber. The main thing to expect is gas: 23 of the 50 people who finished inulin reported minor wind or bloating, though none stopped because of it.
Twenty grams is a lot of inulin all at once, and the trial’s dose isn’t an official recommendation. If you try it:
- Start small. Try a teaspoon or so and build up slowly over a couple of weeks.
- Drink water. This is standard advice with any added fiber.
- Give it a fair test. The trial ran six weeks, so track your pain and stop if it isn’t helping.
- Check first if you have IBS or another gut condition. Inulin ferments in the gut and could make symptoms worse.
Food is a good place to start. Inulin occurs naturally in chicory root and Jerusalem artichokes. Fiber in general is something most people need more of anyway, and our list of 30 high-fiber foods makes that easy. Just remember that those foods weren’t what the trial tested.
What helps knee arthritis the most?
Movement. In this trial, exercise reduced pain at least as much as fiber and also improved function, and it has been a core recommendation for knee and hip osteoarthritis for years. Strong thigh and hip muscles take load off the knee. Keeping your muscle matters here, and so does getting enough protein to support it.
Pain around the hip can come from the same condition. If yours is higher up, read what your hip pain means, and if it’s worse at night, see hip pain at night. Morning stiffness? Here’s why you might feel stiff in the morning.
When should you see a doctor about knee pain?
See your doctor if knee pain lasts, or if it stops you doing everyday things. The NHS says persistent joint symptoms are worth having checked so the cause can be confirmed. Go sooner, or get urgent care, if your knee is hot, red and swollen, if you have a fever, if you can’t put weight on it, or if it looks deformed after an injury. Those aren’t typical of osteoarthritis and need checking quickly.
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Quick questions
What type of fiber helps with arthritis?
The trial tested inulin, a prebiotic fiber found in chicory root. Other fibers weren’t tested in it, so we can’t say whether psyllium or oats would do the same.
How long does fiber take to help knee pain?
The trial measured results after six weeks, so that’s a fair amount of time to test it. We don’t have good evidence for how soon it starts or how long the benefit lasts.
Can fiber replace arthritis medication?
No. Don’t stop any treatment because of this trial. Any fiber would be an add-on to what your doctor recommends, and the trial doesn’t show it can replace anything you already take.
Does inulin cause side effects?
Yes, gas and bloating are common. In the trial, 23 of 50 people had minor stomach effects like wind and bloating, but none stopped because of them. Starting with a small amount may help.
Does fiber help hip arthritis too?
We don’t know. This trial only included people with knee osteoarthritis. Hip arthritis may work in a similar way, but nobody has shown that here.
This article is general information, not medical advice. Fiber isn’t a cure for arthritis. Talk to your doctor about joint pain and before starting a supplement, especially if you take medication or have a gut condition.
Sources
- Kouraki A et al. Effect of Prebiotic Supplementation With and Without Physiotherapy on Pain and Pain Sensitivity in People with Knee Osteoarthritis. Nutrients, 2026
- ScienceDaily: A simple daily fiber supplement reduced arthritis pain and improved strength (Oct 2026)
- NHS: Osteoarthritis
- NIAMS: Osteoarthritis