Research, trials, and evidence
If you have Inflammatory Bowel Disease (IBD), you have probably seen supplements marketed as game-changers for gut health. Vitamin D, curcumin, omega-3s, probiotics: the recommendations show up on social media, in health food stores, and sometimes from well-meaning friends. Some of these have genuine research behind them. Others are mostly marketing. The challenge is that 70% of social media posts about IBD dietary advice are not evidence-based, and the academic literature that does exist is often locked behind paywalls or written for researchers, not patients. This article breaks down the major supplements for IBD using a consistent framework: what the clinical evidence supports, where the data is inconclusive, and what your gastroenterologist needs to know before you start anything new.
Vitamin D: Strong Rationale, Growing Evidence
Vitamin D deficiency is common in IBD. The nutrient plays a direct role in maintaining intestinal barrier integrity and regulating the inflammatory immune response, which makes correction of deficiency a priority regardless of whether supplementation treats the disease itself. A 2023 systematic review and meta-analysis in Inflammatory Bowel Diseases found that vitamin D supplementation effectively corrected deficiency levels and was associated with improvement in both clinical and biochemical disease activity scores.
A 2025 real-world study published in PubMed added weight to these findings. Among IBD patients, vitamin D supplementation was associated with a 34% relative reduction in IBD-related emergency department visits, a 53% reduction in hospitalizations, and a 25% reduction in corticosteroid prescriptions. These are meaningful numbers for a low-cost intervention with minimal side effects. However, the 2025 Journal of Crohn's and Colitis guidelines stop short of recommending vitamin D specifically for maintaining remission, noting that while supplementation is not contraindicated and may confer benefit, the evidence does not yet support it as a standalone therapy.
Bottom line: If your vitamin D levels are low, supplementation is well-supported. Ask your GI to check your serum 25-hydroxyvitamin D levels and aim to correct any deficiency. As a treatment for IBD itself, the signal is promising but not definitive.
Curcumin: Encouraging for Ulcerative Colitis, Unproven for Crohn's
Curcumin, the active compound in turmeric, has strong anti-inflammatory and antioxidant properties in laboratory studies. A 2025 systematic review and meta-analysis of placebo-controlled randomized clinical trials evaluated its clinical use in IBD and found that randomized trials showed promising results for both Crohn's disease and ulcerative colitis. All trials reported that curcumin was well tolerated with no serious side effects.
The evidence is stronger for ulcerative colitis. The European Crohn's and Colitis Organization (ECCO) and the European Society of Paediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) have noted that curcumin may be considered as an additional therapy for inducing and maintaining clinical remission in mild to moderate ulcerative colitis. For Crohn's disease, the picture is less clear. The same systematic review found that a definitive conclusion about curcumin in Crohn's cannot be made due to the lack of low-bias-risk studies. The overall methodological quality of the available evidence remains very low, with concerns about imprecision and publication bias.
Bottom line: If you have mild to moderate ulcerative colitis, curcumin alongside your standard treatment is worth discussing with your GI. For Crohn's disease, the evidence is too thin to make a recommendation either way. Curcumin is generally safe, but dosing varies widely across studies, and turmeric from your spice rack is not the same as a standardized curcumin supplement.
Omega-3 Fatty Acids: Anti-Inflammatory in Theory, Mixed in Practice
Omega-3 fatty acids, particularly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) found in fish oil, reduce inflammation through well-understood biological pathways. When incorporated into cell membranes, they produce fewer pro-inflammatory compounds and generate specialized pro-resolving mediators that help shut down inflammation. That mechanism sounds ideal for IBD. The clinical reality is more complicated.
A large meta-analysis of 83 randomized controlled trials including over 41,000 participants found that increasing long-chain omega-3 intake may reduce the risk of IBD relapse and disease worsening. However, a systematic review in the British Journal of Nutrition concluded that the evidence does not allow firm recommendations about the usefulness of omega-3s in IBD, particularly for treating active disease. The 2025 ECCO guidelines do not recommend omega-3 supplementation for maintenance of remission in either Crohn's disease or ulcerative colitis.
Bottom line: Omega-3s are safe and may offer modest benefit for reducing relapse risk, but they are not a substitute for medical therapy. If you already eat fatty fish regularly, you may not need a supplement. If you are considering fish oil capsules, discuss dosing with your GI team, as high doses can cause GI side effects that may be difficult to distinguish from IBD symptoms.
Probiotics: Condition-Specific Evidence
Probiotics are the most complex category because different bacterial strains do different things, and the evidence varies sharply between ulcerative colitis and Crohn's disease. The high-concentration multi-strain probiotic VSL#3 (now marketed as Visbiome in some regions) has the strongest evidence base. A meta-analysis of randomized trials found that VSL#3 achieved remission in 43.8% of patients with active mild to moderate ulcerative colitis, compared to 24.8% on placebo. Response rates were 53.4% versus 29.3%. A Cochrane Review of 14 studies indicated that probiotics can induce clinical remission during active ulcerative colitis and may help prevent recurrence.
For Crohn's disease, the picture is far less encouraging. Trials of various probiotic strains, including Lactobacillus rhamnosus GG and Saccharomyces boulardii, have not demonstrated consistent benefit for maintaining remission. The bacterial ecology of Crohn's differs from ulcerative colitis, and what works in one condition cannot be assumed to work in the other.
Bottom line: If you have ulcerative colitis, ask your gastroenterologist whether a high-concentration multi-strain probiotic like VSL#3 makes sense alongside your current treatment. If you have Crohn's disease, the evidence for probiotics is weak. In either case, a generic probiotic from the supplement aisle is unlikely to contain the strains, concentrations, or quality control used in the clinical trials.
Correcting Deficiencies: Iron, B12, Folate, and Zinc
Some supplements for IBD are less about treating inflammation and more about correcting nutritional deficiencies that the disease itself causes. Micronutrient deficiencies occur in more than half of IBD patients, with iron, vitamin B12, folate, and zinc among the most common. These are not optional extras.
Iron deficiency leading to anemia is one of the most frequent complications of IBD, driven by both blood loss from intestinal ulcers and impaired absorption. Vitamin B12 is absorbed in the terminal ileum, which means patients with ileal Crohn's disease or those who have had ileal resection surgery are at particular risk. Folate levels can drop in patients taking methotrexate or sulfasalazine, and zinc deficiency has been linked to increased Crohn's disease complications through impaired intestinal healing.
Bottom line: Have your GI team screen for deficiencies in iron, B12, folate, zinc, and vitamin D at regular intervals. Supplementation to correct a confirmed deficiency is standard medical care, not alternative medicine. Do not self-dose iron, as excess iron can be toxic to the liver, and have your levels tested first.
What Your GI Needs to Know
Before adding any supplement to your routine, bring it to your next gastroenterology appointment rather than starting on your own. Your GI needs to know what you are taking for three reasons: some supplements interact with IBD medications, symptom changes from a new supplement can be confused with disease activity, and your doctor cannot interpret lab results accurately without knowing your full regimen. Complementary therapies in IBD are exactly that, complementary to standard medical treatment, not replacements for it.
Track your supplements alongside your symptoms in Aidy to see if they are actually making a difference for you. When you can show your GI a clear record of what you started, when you started it, and how your symptoms responded, the conversation shifts from anecdote to evidence.