Inflammatory bowel disease involves more than immune overactivity. In both ulcerative colitis and Crohn’s disease, the intestinal epithelium shows signs of endoplasmic reticulum (ER) stress: proteins misfold, the unfolded protein response stays chronically activated, and the barrier function of the gut lining degrades. Because TUDCA‘s best-characterized mechanism is acting as a chemical chaperone that reduces ER stress and protein aggregation, the gut has been an obvious research target.
Until recently that research was entirely in mice. In 2025 a group at Washington University published the first human trial of oral TUDCA in active ulcerative colitis. This article covers what it found and, just as importantly, what its design cannot establish. None of this is medical advice, and IBD is a condition where self-directed supplement changes can delay effective treatment.
Key Takeaways
- An open-label trial gave patients with moderate-to-severely active ulcerative colitis oral TUDCA at 1.75 or 2 g/day for six weeks [1]. Thirteen participants completed it; eleven were evaluable for clinical response.
- Mean total Mayo score (a combined clinical and endoscopic disease-activity measure) fell from 9 to 4.5 (P < 0.001), with mucosal biopsies showing reduced ER stress and inflammation plus increased markers of epithelial restitution [1].
- There was no control group, no blinding, and 13 participants. The authors themselves concluded that a randomized controlled trial is warranted [1].
- The trial dose, 1.75 to 2 g/day, is well above the 500 to 1500 mg/day range typical of TUDCA supplement labels.
- Animal work supports the mechanism: TUDCA dampened Crohn’s-like ileitis in TNFΔARE/WT mice and protected bile acid homeostasis under inflammation [2], and reduced disease in chemically induced colitis models [3].
Why ER Stress Is a Credible IBD Target
The intestinal epithelium turns over every few days and secretes enormous quantities of protein, particularly mucins from goblet cells and antimicrobial peptides from Paneth cells. That secretory load makes the ER of these cells unusually vulnerable. When protein folding capacity is exceeded, misfolded protein accumulates, the unfolded protein response activates, and if the stress is unresolved the cell shifts toward inflammatory signaling and apoptosis instead of repair.
Genetic evidence supports this: several IBD risk genes sit in ER stress and autophagy pathways. In practical terms, chronic ER stress in the epithelium potentiates barrier dysfunction and impairs mucosal healing, which is precisely the failure mode that distinguishes IBD in remission from IBD that keeps flaring [1].
TUDCA acts as a chemical chaperone, stabilizing protein folding and reducing aggregation. That places it upstream of the inflammatory cascade rather than suppressing the immune response directly, which is a different mechanism from every currently approved UC drug class.
The 2025 Open-Label Human Trial
Investigators enrolled patients with moderate-to-severely active ulcerative colitis, defined as a Mayo score of 6 or higher with an endoscopic subscore of at least 1. Patients with known hepatic disorders, or who had changed their UC therapy in the prior 60 days, were excluded. Participants received oral TUDCA at 1.75 or 2 g/day for six weeks [1].
The primary outcome was change in ER stress markers in mucosal biopsies, with safety, tolerability, and disease activity as secondary outcomes. Endoscopy with biopsy, blood, and stool were collected at enrollment and again at six weeks.
Thirteen participants completed the study and eleven were evaluable for clinical response. TUDCA was well tolerated, with transient dyspepsia the most common side effect. Mucosal biopsies showed significant reductions in ER stress and inflammation along with an increase in markers of epithelial restitution. Clinical, endoscopic, and histologic disease activity all improved, with mean total Mayo score falling from 9 to 4.5 (P < 0.001) [1].
That the biopsy-level mechanism marker and the clinical score moved in the same direction is the most interesting part of the result. It is consistent with the drug doing what the hypothesis predicted rather than producing symptomatic relief through an unrelated route.
Four Reasons to Hold This Loosely
No control group. Ulcerative colitis fluctuates. Patients enroll in trials when they feel worst, which is statistically when they are most likely to improve anyway. Without a placebo arm there is no way to separate drug effect from regression to the mean.
No blinding. Both patients and investigators knew everyone was receiving TUDCA. Mayo scoring includes a patient-reported component, and endoscopic subscoring involves clinician judgment. Open-label designs reliably produce larger apparent effects than blinded ones.
Thirteen participants. That is a mechanism-of-action study, not an efficacy study. Eleven evaluable for clinical response is small enough that a couple of unusual responders shape the mean.
Preprint status. The report appeared on medRxiv, which means it had not completed peer review at the time of posting [1].
The authors were direct about this: their stated conclusion was that a randomized controlled trial of adjunctive TUDCA in UC is warranted [1]. That is the correct reading, and it is worth noting they framed it as adjunctive, alongside existing therapy, not as a replacement for it.
The Animal Evidence Behind the Trial
The human trial did not come out of nowhere. A Belgian group showed that exposing Caco-2 intestinal cell monolayers to TNFα impaired expression of bile acid nuclear receptors (FXR, PXR, VDR) and bile acid transporters, and that co-incubation with TUDCA antagonized that downregulation [2]. In TNFΔARE/WT mice, an established model of Crohn’s-like ileitis, eleven weeks of TUDCA attenuated the ileitis and alleviated the downregulation of those same genes [2].
Separately, a TUDCA liposome formulation alleviated DSS-induced ulcerative colitis in mice by restoring intestinal barrier function and gut microbiota [3], and TUDCA attenuated colitis-associated colon cancer in mice by inhibiting NF-κB signaling [4].
The consistency across models, Crohn’s-like ileitis, chemically induced colitis, and colitis-associated carcinogenesis, is what made a human trial reasonable to run. It does not substitute for one.
What This Evidence Can and Cannot Tell Us
It can tell us that six weeks of oral TUDCA at 1.75 to 2 g/day was tolerated in people with active UC and that biopsy ER stress markers moved in the predicted direction. That is a genuine and non-trivial finding, and it justifies a proper trial.
It cannot tell us whether TUDCA works. An uncontrolled 13-person open-label study of a relapsing-remitting disease is not capable of answering that question, by design.
Practically: ulcerative colitis left inadequately treated causes cumulative bowel damage and raises colorectal cancer risk. Substituting a supplement for prescribed therapy on the strength of this trial would be a serious error. If TUDCA interests you as an addition to existing treatment, that belongs in a conversation with your gastroenterologist, who can also weigh the dose gap between the 2 g/day used in the trial and what supplement labels typically supply.
Frequently Asked Questions
How much TUDCA did the ulcerative colitis trial use?
1.75 or 2 g per day for six weeks [1]. That is substantially more than the 500 to 1500 mg/day range most TUDCA supplements are dosed at, which matters when interpreting whether a typical supplement regimen resembles what was studied.
Does TUDCA help Crohn’s disease too?
The human trial enrolled ulcerative colitis patients only. The Crohn’s evidence is animal-level: TUDCA dampened ileitis in TNFΔARE/WT mice, a Crohn’s-like model, and protected bile acid homeostasis under inflammatory conditions [2]. No human Crohn’s trial has been published.
Was the ulcerative colitis result peer-reviewed?
It was posted as a medRxiv preprint, meaning it had not completed peer review at posting [1]. Preprints are legitimate ways to share findings early, but they have not passed the review filter that catches methodological problems.
Can TUDCA replace my UC medication?
No. The trial studied TUDCA added to stable existing therapy, not instead of it, and the authors explicitly framed a future trial as testing adjunctive use [1]. Stopping prescribed UC therapy risks a flare and cumulative bowel damage.
References
- Tauroursodeoxycholic Acid (TUDCA) Reduces ER Stress and Lessens Disease Activity in Ulcerative Colitis. medRxiv (preprint) (2025).
- Tauroursodeoxycholic acid protects bile acid homeostasis under inflammatory conditions and dampens Crohn’s disease-like ileitis. Laboratory Investigation (2017).
- Tauroursodeoxycholic acid liposome alleviates DSS-induced ulcerative colitis through restoring intestinal barrier and gut microbiota. Colloids and Surfaces B: Biointerfaces (2024).
- Tauroursodeoxycholic acid attenuates colitis-associated colon cancer by inhibiting nuclear factor kappaB signaling. Journal of Gastroenterology and Hepatology (2019).
These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure, or prevent any disease. Content is for informational purposes only and is not medical advice; consult a qualified healthcare provider before starting any supplement. As an Amazon Associate we earn from qualifying purchases.
