It’s completely normal to hope that there is a supplement or diet that can ease the pain of arthritis. I hear it in clinic every week:
“What about turmeric?” “Does glucosamine work?” “Should I be taking vitamin D?”
The idea that you can take something simple that helps rebuild cartilage or calm inflammation is appealing. Who wouldn’t want that? But the truth is more complicated. Some supplements have plausible biological mechanisms and small studies suggesting benefits, but when tested in large, independent clinical trials, most do not perform as well as people hope.
The good news is that there are dietary patterns that consistently improve inflammation, pain, and function.
Why It Is So Hard to Prove Supplements Work
To understand why the evidence for supplements is so mixed, it helps to look at how treatments are tested.
High-quality studies rely on randomised controlled trials (RCTs), which are considered the gold standard for determining whether a treatment truly works. Participants are randomly assigned to receive either the treatment or a placebo, and ideally neither they nor the researchers know who is taking which until the end. This helps eliminate bias and expectation effects.
That kind of rigour is necessary because conditions like osteoarthritis naturally fluctuate. Pain can improve for reasons that have nothing to do with the treatment. Without randomisation and blinding, you cannot tell whether a supplement caused the improvement or whether the person simply had a better week.
The problem is that these studies are expensive, and supplements do not attract the same level of funding as pharmaceutical drugs. They cannot be patented, so there is little commercial incentive to spend millions proving something that anyone can manufacture. As a result, most supplement research is small, inconsistent, and often industry-funded.
Why the NHS Does Not Recommend Most Supplements
In the UK, the NHS and NICE (National Institute for Health and Care Excellence) only recommend treatments that consistently show clear benefit across large populations. They also weigh cost-effectiveness and safety.
So while you might see small studies showing modest improvements with glucosamine, chondroitin, or turmeric, these results are not strong or consistent enough to change clinical guidelines. For a supplement to make it into NICE recommendations, it must outperform placebo repeatedly, not just once in a niche study.
That’s why, despite decades of marketing, neither glucosamine nor chondroitin is recommended by NICE for osteoarthritis management.
The GAIT Trial: What We Learned
The biggest and most rigorous test of glucosamine and chondroitin came in 2006 with the Glucosamine/Chondroitin Arthritis Intervention Trial (GAIT), published in The New England Journal of Medicine.
This was a large, independently funded trial involving 1,583 people with knee osteoarthritis. Participants were randomly assigned to receive:
- Glucosamine hydrochloride
- Chondroitin sulphate
- Both combined
- Celecoxib (a prescription anti-inflammatory used as a positive control)
- Placebo
The trial ran for six months, measuring changes in pain and function using the WOMAC scale (a standardised arthritis scoring tool).
Here is what happened:
- About 60 per cent of participants taking placebo felt meaningful pain relief, showing how powerful expectation can be.
- Neither glucosamine nor chondroitin alone was better than placebo.
- Even the combination only helped a small subgroup of people with more severe pain, and that finding was statistically uncertain because the group was small.
- The celecoxib group, by contrast, showed a clear and consistent improvement.
A two-year follow-up study looked at whether these supplements slowed cartilage loss on X-ray. The result: no difference in joint-space narrowing between any of the groups.
The GAIT trial set the tone for clinical guidelines worldwide. Its message was clear: while glucosamine and chondroitin are safe, they do not reliably reduce pain or slow osteoarthritis progression for most people.
So Why Do People Feel Better on Turmeric, Fish Oil, or Supplements?
It is important not to dismiss people’s lived experience. Many patients genuinely feel better when they start a supplement, and that improvement is real to them. There are a few likely explanations.
1. Reduced chronic inflammation
Certain compounds, such as curcumin in turmeric or omega-3 fatty acids in fish oil, do have measurable effects on inflammation in laboratory studies. Curcumin can inhibit inflammatory pathways such as NF-κB and COX-2, which are the same mechanisms targeted by anti-inflammatory drugs.
However, absorption is a problem. Curcumin is poorly bioavailable, meaning most of what you swallow never reaches your bloodstream. Some newer formulations include black pepper extract (piperine) or fats to increase absorption, but results vary.
2. The placebo effect
When you believe something will help, your brain releases endorphins and other neurotransmitters that genuinely reduce pain. It is not “all in your head” – it is a neurochemical effect with measurable impact. The placebo effect in arthritis research can be as strong as many drug interventions.
3. Timing and natural variation
Arthritis pain naturally waxes and wanes. If you start a supplement as a flare is easing, it is easy to assume the pill caused the improvement.
So while the benefit might not be directly from the supplement itself, the overall impact – feeling more in control, more hopeful, and more proactive – still matters.
The Vitamin D Connection
Vitamin D is often lumped in with supplements like glucosamine, but it is quite different. It is not a “joint supplement”; it is a hormone precursor that influences how the immune system, muscles, and bones function.
Here is how it connects to arthritis.
1. Immune regulation
- Vitamin D binds to receptors on immune cells, calming the inflammatory response.
- It reduces pro-inflammatory cytokines such as TNF-α, IL-1β, and IL-6, and promotes regulatory T-cells that keep inflammation under control.
- It downregulates NF-κB, a master switch for inflammatory gene expression.
2. Cartilage protection
Cartilage cells (chondrocytes) also have vitamin D receptors. Adequate levels help them regulate turnover and reduce the enzymes (MMPs) that degrade cartilage.
3. Pain sensitivity and fatigue
Low vitamin D increases pain sensitivity by affecting serotonin and dopamine pathways in the brain. Many patients with chronic pain report fatigue and mood changes that improve once deficiency is corrected.
4. Muscle and bone strength
Vitamin D helps the body absorb calcium and phosphate, strengthening bones and improving muscle contraction. It particularly supports type II muscle fibres, which protect joints during movement.
So, while vitamin D does not reverse arthritis, correcting a deficiency can reduce inflammation, improve strength, and lower pain perception. In the UK, where deficiency is common in winter, supplementation can make a tangible difference to how people feel day to day.
Diet Patterns: The Bigger Lever
If there is one consistent theme in the research, it is that diet matters more than any single supplement.
The Mediterranean diet, which is high in vegetables, fruit, legumes, olive oil, oily fish, and whole grains, is the most studied dietary pattern for reducing inflammation. People following this diet tend to have lower levels of inflammatory markers such as CRP and IL-6, better cardiovascular health, and improved joint function.
It works because nutrients interact. The combination of antioxidants, fibre, unsaturated fats, and polyphenols creates a systemic anti-inflammatory effect that no single capsule can replicate.
On the other hand, diets high in processed food, refined sugars, and trans fats promote inflammation and metabolic stress, which can make arthritis worse.
If Money Were No Object
If you could do this perfectly, you would:
- Run baseline blood tests for vitamin D, omega-3 index, iron, B12, and inflammatory markers such as CRP and IL-6.
- Supplement only deficiencies rather than guessing.
- Adopt a Mediterranean-style diet as your foundation.
- Monitor symptoms and retest periodically to track changes.
That is what a genuinely evidence-based, personalised nutrition plan looks like, not a shelf full of untested supplements.
Take-Home Message
- Supplements: Generally safe, but benefits are small and inconsistent.
- Glucosamine and chondroitin: Sound logical, but large studies show little effect.
- Vitamin D: Worth testing and correcting if low; it modulates inflammation and muscle function but does not repair joints.
- Turmeric and fish oil: Can modestly reduce inflammation, but absorption and individual response vary.
- Diet: The single most powerful tool for long-term joint and overall health.
There is no magic pill for arthritis. But by focusing on a balanced diet, maintaining a healthy weight, staying active, and correcting genuine deficiencies, you can dramatically improve how your joints feel and function – with or without supplements.
Author: Ed Thompson, Physiotherapist and Clinic Owner at Instant Physio
Helping people move better, live stronger, and understand their pain.