Arthros | Patient Deep Dive
SUPPLEMENTS
Vitamin D, fish oil, and the rest of the supplement bag
• Angelo Papachristos PT, ACPAC • Unity Health Toronto
Two supplements with real evidence, and one bag full of bottles that may be doing less than you think.
A woman in her late 50s with seropositive rheumatoid arthritis brings a clear Ziploc bag to her appointment. Inside are seven bottles: turmeric, fish oil, a high-dose vitamin D, a 'joint formula' with glucosamine and chondroitin, a probiotic, magnesium, and something her daughter ordered online called 'anti-inflammation complex.' Her methotrexate is in the bag too. She has been skipping doses for three months because her naturopath told her the supplements would do the same job with less risk, and she wants to know which bottles to keep.
What you usually hear about supplements is wrong in two directions
Two messages dominate the supplement conversation in rheumatology. The first is that supplements are at best harmless background noise and at worst a way to feel like you are doing something while avoiding the medication that actually controls your disease. This is what many rheumatologists communicate, often by saying nothing at all when a supplement is mentioned in the medication review. The second is that supplements are foundational, and that pharmaceuticals are downstream patches for problems your nutrition could solve. This is what many naturopaths communicate, often with more confidence than the evidence warrants.
Two supplements have enough evidence behind them to take seriously: vitamin D and fish oil. Most of the rest of the bottles in the bag don't do what the labels say. A few can cause real harm. The conversation worth having is which is which.
Vitamin D: real, modest, and mostly for prevention and bone
The biggest piece of evidence on vitamin D and autoimmune disease comes from the VITAL trial. Around 26,000 adults over age 50 in the United States were randomized to vitamin D 2000 IU daily, marine omega-3 fatty acids 1 gram daily, both, or placebo, and followed for about five years. The autoimmune disease analysis, published by Hahn and colleagues in BMJ in 2022, found that the vitamin D arm had roughly a 22% lower rate of newly diagnosed autoimmune disease, mostly rheumatoid arthritis, polymyalgia rheumatica, autoimmune thyroid disease and psoriasis. The absolute numbers are small, around one fewer case per hundred people over five years. This is a real signal, in people who did not already have autoimmune disease.
For people who already have rheumatic disease, the picture is thinner. Lupus cohorts consistently show low vitamin D levels tracking with higher disease activity, and several small supplementation trials suggest modest improvements in fatigue and disease activity scores. None of these is large or definitive. In RA, supplementing vitamin D in people already on methotrexate has not been shown to reduce flares or slow joint damage in any convincing trial.
Where vitamin D earns its place without argument is bone health, especially with steroids. The 2017 American College of Rheumatology guideline on glucocorticoid-induced osteoporosis recommends calcium and vitamin D supplementation for essentially every adult on chronic prednisone. If you are on prednisone for lupus, vasculitis, polymyalgia rheumatica, or myositis, vitamin D is not optional. A reasonable target is a serum 25-hydroxyvitamin D level above 75 nmol/L (30 ng/mL), achieved with 1000 to 2000 IU daily for most people. The megadose habit, 50,000 IU weekly indefinitely, is where toxicity (hypercalcemia, kidney stones) starts to appear in clinic.
Omega-3: the dose almost nobody takes
The omega-3 story is more interesting than its reputation. Multiple RA trials and meta-analyses going back to the 1990s have shown that fish oil reduces RA symptoms at doses around 2.7 to 3 grams of EPA and DHA combined per day. The effect is most consistent on morning stiffness and joint tenderness. The effect on radiographic progression is essentially zero. So omega-3 helps with how the disease feels. It does not change what the disease is doing to your joints structurally.
Here is the part that matters in clinic. Most off-the-shelf fish oil capsules contain 300 to 500 mg of combined EPA and DHA per capsule. The trial dose translates to six to ten capsules a day, depending on the brand. The woman from the start of this piece had been taking one fish oil capsule daily for two years, assuming that the brand mattered more than the dose. Her actual daily intake of EPA and DHA was around 350 mg, roughly a tenth of the dose used in the trials. People who say they 'tried fish oil and it didn't help' have almost always taken one capsule daily. Taking one is taking nothing.
In other rheumatic conditions, the omega-3 evidence is weak. Small lupus and scleroderma trials hint at benefits without convincing follow-up. In axial spondyloarthritis, the evidence base is small enough that no recommendation is defensible. If you want to try fish oil for RA pain at a real dose for three months and see if it helps you, that is a reasonable experiment. If you have been taking a single capsule daily as background noise, you are not running the experiment the trials ran.
Where the supplement bag goes wrong
Glucosamine and chondroitin are the most consumed joint supplements in North America. The GAIT trial, published by Clegg and colleagues in the New England Journal of Medicine in 2006, randomized about 1500 people with knee osteoarthritis to glucosamine, chondroitin, the combination, celecoxib, or placebo. The primary endpoint, pain reduction, was not met by glucosamine, chondroitin or their combination. A subgroup with moderate-to-severe pain showed a small signal for the combination, but this has not held up convincingly in replication. Cochrane reviews on glucosamine for OA conclude the effect is small at best and may be inflated by industry-funded trials. If glucosamine clearly helps you and you have been taking it for six months, fine. If you have been taking it for six months without certainty it helps, you are paying for something that probably is not working.
Turmeric and curcumin deserve a sharper warning. Short-term trials in knee OA show modest pain reduction over a few weeks, in some cases comparable to ibuprofen. The problem is hepatotoxicity, meaning liver damage. The US Drug-Induced Liver Injury Network has documented a rising number of cases of significant liver injury attributed to turmeric supplements, especially the newer 'high-bioavailability' formulations that pair curcumin with black pepper extract (piperine). Several cases have required liver transplant. If you are on methotrexate, leflunomide, or another DMARD with liver risk, adding daily turmeric is a real interaction question worth raising before you start, and a good reason for an extra liver-enzyme check if you have already started.
Then there is the cocktail itself. Patients with rheumatic disease frequently take ten or more supplements at once, often added in sequence by different practitioners who never see the full list. St. John's Wort lowers blood levels of cyclosporine and tacrolimus through liver enzyme induction, a serious issue for the smaller group of patients on those drugs. High-dose iron interferes with thyroid medication absorption. Calcium binds many things. The risk in a large supplement stack is rarely one specific ingredient. It is the cumulative chance that something in there is interfering with something that matters.
I have not written about vitamin K2, MSM, boswellia, ashwagandha, collagen peptides, or the dozen other supplements that show up in clinic. The evidence base for each is small short-term trials, often industry-sponsored and often with comparators chosen to flatter the effect. Some of these may turn out to do something useful. Right now, none has the evidence base that vitamin D and fish oil do, and none should be marketed to you as a substitute for treatment that does.
The burden of evidence for a supplement belongs to the supplement, not to you. If a bottle in your bag cannot be explained by someone on your rheumatology team in a single sentence, take it out of the bag.
What to do, and the conversation to have
Before your next appointment, gather every supplement, vitamin, herbal product, protein powder, and tea you take regularly. Put them in a bag. Bring the bag in. Ask two specific questions: which of these is likely doing anything for me, and which could be interacting with my medication. If the person you see in clinic is a nurse, advanced practice physiotherapist, or pharmacist, this conversation is in their scope. They have it every week, and they are usually the person on the team with the most current handle on supplement-drug interactions.
What this does not mean
None of this is a reason to stop your DMARD or biologic. Vitamin D and fish oil at best soften symptoms; they do not control the autoimmune disease driving your joint damage. If you are considering stopping a rheumatology medication, that is a conversation to have at the appointment, not on the way to it.
References
VITAL trial: vitamin D and incident autoimmune disease. Hahn J et al, BMJ 2022. The VITAL substudy showing roughly a 22% reduction in newly diagnosed autoimmune disease over five years of 2000 IU daily vitamin D in adults over 50.
https://www.bmj.com/content/376/bmj-2021-066452
VITAL trial main results. Manson JE et al, New England Journal of Medicine 2019. The parent trial of vitamin D and marine omega-3 supplementation for cancer and cardiovascular outcomes.
https://www.nejm.org/doi/full/10.1056/NEJMoa1809944
GAIT trial of glucosamine and chondroitin in knee OA. Clegg DO et al, New England Journal of Medicine 2006. Multicentre RCT showing no significant pain benefit of glucosamine, chondroitin, or the combination over placebo at the primary endpoint.
https://www.nejm.org/doi/full/10.1056/NEJMoa052771
ACR 2017 Guideline for the Prevention and Treatment of Glucocorticoid-Induced Osteoporosis. Buckley L et al, Arthritis Care & Research 2017. Recommends calcium and vitamin D for essentially all adults on chronic glucocorticoids.
https://acrjournals.onlinelibrary.wiley.com/doi/10.1002/art.40137
Meta-analysis of omega-3 for inflammatory joint pain. Goldberg RJ, Katz J, Pain 2007. Pooled analysis of omega-3 supplementation trials showing modest reductions in joint tenderness, morning stiffness, and NSAID requirement at higher doses.
Turmeric-associated liver injury in the Drug-Induced Liver Injury Network. Halegoua-DeMarzio D et al, American Journal of Medicine 2023. Case series describing significant hepatotoxicity attributed to turmeric supplements, including cases requiring transplant.
This article is patient education from RheumAcademy. It is general information based on published evidence and clinical practice, not a personalized medical recommendation. The right answer for you depends on your specific diagnosis, other medical conditions, and current medications. Use this as material for the conversation with your rheumatology team, not as a substitute for it.
Angelo Papachristos PT, ACPAC • Advanced Practice Physiotherapist • Martin Family Arthritis Care & Research Centre, St. Michael's Hospital, Unity Health Toronto • Co-Founder, RheumAcademy