This Overlooked Nutrient May Help With Knee Osteoarthritis — No Medication Required
If you've been managing knee pain and feel like you've already tried everything, here's something you probably haven't considered: your gut.
A new study1 found that taking a prebiotic fiber called inulin significantly reduced knee osteoarthritis pain in just six weeks, with results comparable to a structured exercise program. The findings add to a growing body of research on the gut-joint connection, and they suggest that what you feed your gut bacteria may matter more for joint health than most people realize.
A fiber your gut bacteria actually eat
Inulin is a type of soluble fiber found naturally in chicory root, Jerusalem artichokes, and other plant sources. Unlike prebiotics that introduce live bacteria into your gut, inulin works by feeding the beneficial bacteria already living there. When those bacteria break down inulin, they produce compounds called short-chain fatty acids, including one called butyrate, which have well-documented anti-inflammatory effects throughout the body.
Researchers have increasingly been looking at inulin as a potential tool for managing systemic inflammation, and this new trial is one of the first to test that idea directly in people with knee osteoarthritis.
117 people, four groups, six weeks
A total of 117 adults with knee osteoarthritis were split into four groups for six weeks: one group took 20 grams of inulin per day, one group did digital physiotherapy-supported exercise (via an app called Joint Academy), one group did both, and one group took a placebo. Participants were 58.1% female, with an average age of 67.5 years.
The main thing researchers were measuring was pain, using a standard 0–10 scale. They also tracked grip strength, mobility (how quickly people could stand up and walk), and markers of pain sensitivity. Blood samples were taken to measure levels of short-chain fatty acids and a gut hormone called GLP-1.
Both inulin & exercise reduced pain — but in different ways
Both inulin and exercise reduced pain significantly compared to the placebo group. People taking inulin saw their pain scores drop by an average of 1.11 points, while the exercise group saw a drop of 1.55 points. Both improvements crossed the threshold researchers consider clinically meaningful, so participants actually felt the difference in their daily lives.
But inulin did something exercise didn't, by improving how the body processes pain. People in the inulin group showed improvements in pressure pain thresholds (how much pressure it takes before something feels painful) and temporal summation (a measure of how the spinal cord amplifies repeated pain signals). These changes suggest inulin may be influencing pain at a deeper level, not just masking it.
Exercise, on the other hand, led to better results for physical function (people moved faster and could do more sit-to-stand repetitions) which inulin alone didn't match.
The gut hormone no one expected to show up
One of the more intriguing findings involves a gut hormone called GLP-1 (glucagon-like peptide-1), which most people know in the context of blood sugar and appetite regulation. Only the inulin group showed significant increases in both butyrate and GLP-1 levels.
While inulin raised butyrate levels, researchers found no meaningful link between butyrate changes and pain relief. That led them to look at GLP-1 as a possible explanation instead.
Higher GLP-1 levels were associated with improved grip strength, pointing to a possible connection between gut signaling and muscle function.
It's worth noting that this GLP-1 finding was exploratory (it wasn't part of the original study plan), and the association was nominal, meaning it didn't hold up after statistical correction for multiple comparisons.
Researchers describe it as hypothesis-generating, something worth investigating further rather than drawing firm conclusions from.
Which one people actually stuck with
Both approaches worked for pain, but they worked differently, and one had a clear practical advantage. The dropout rate for the inulin group was just 3.6%, compared to 21% for the exercise group.
That's a significant gap, and it matters in the real world. A supplement people actually stick with may ultimately deliver more benefit than an exercise program many abandon.
That said, exercise produced meaningful improvements in mobility that inulin didn't. The two interventions appear to target different aspects of osteoarthritis, which suggests they could work well together rather than as substitutes for each other.
Before you add inulin to your routine
Before adding inulin to your routine, a few important caveats are worth understanding:
- Short study duration: Six weeks is a relatively brief window, whether these benefits persist or grow over months of consistent use is still unknown.
- Supplement vs. whole food: The study used supplemental inulin at 20 g/day, a dose that would be difficult to reach through food alone.
- Exercise blinding limitations: Participants knew whether they were doing exercise, which may have influenced how they reported their pain.
- Exploratory GLP-1 data: The GLP-1 findings were not part of the original study plan and should be considered preliminary.
- Underpowered for synergy: The study wasn't designed to detect whether inulin and exercise work better together, so the absence of a combined effect doesn't mean one doesn't exist.
Where inulin actually shows up in your diet
You don't need a supplement to start increasing your inulin intake. Chicory root and Jerusalem artichokes (also called sunchokes) are among the most concentrated natural sources. Other commonly cited inulin-rich foods include garlic, onions, leeks, and asparagus, which are all easy to work into everyday cooking and consistently linked to gut microbiome benefits.
Beyond inulin specifically, eating a wide variety of prebiotic fiber supports a broader range of beneficial gut bacteria. Pairing inulin-rich foods with other anti-inflammatory foods may offer additional benefits for the body as a whole. If you're considering a prebiotic supplement, it's worth talking to a healthcare provider first. Inulin can cause bloating at higher doses, particularly if you're not used to a high-fiber diet (we've got you covered for reaching your daily fiber targets).
The takeaway
Osteoarthritis management has long centered on exercise, weight management, and pain medication. This study doesn't replace any of those approaches, but it does suggest the gut may be a meaningful and largely overlooked part of the picture. If you're looking for a low-risk place to start, increasing inulin-rich foods in your diet is a reasonable first step while the research continues to develop.
