π Simple Summary
TUDCA is a naturally occurring bile acid with a surprising second job: it acts as a “chemical chaperone” that helps your cells fold proteins correctly. When proteins misfold β which happens more as we age β cells experience what scientists call “ER stress,” and this drives aging in every organ. TUDCA reduces this stress. The science is compelling at the cellular level, and animal studies show TUDCA extends lifespan in worms and improves physical function in old mice. In humans, TUDCA has been tested in ALS, multiple sclerosis, and ulcerative colitis with mixed results β it appears safe and shows biological activity, but hasn’t yet delivered a clear win in a major clinical trial. For healthy aging, the evidence puts TUDCA in the “intriguing but unproven in humans” category.
The detailed breakdown continues below for those who want the full science.
π» TUDCA (Tauroursodeoxycholic Acid)
What if a single molecule could reduce the cellular stress that underlies nearly every age-related disease β from muscle loss to neurodegeneration β and it’s been sitting in traditional medicine for over 2,000 years?
π₯ Evidence Tier: Silver β Compelling mechanistic data, multiple human trials, lifespan extension in animals, but no human longevity trials and mixed results in major clinical endpoints.
βοΈ At a Glance: Pros and Cons
β οΈ We are researchers, not doctors. Nothing on this page is medical advice. Always consult your physician before starting any supplement, especially one with effects on liver function and bile acid metabolism.
β Pros
Reduces ER stress: TUDCA is one of the few supplements that directly addresses protein misfolding, a core aging mechanism.
Extends lifespan in animals: A 2025 study showed TUDCA extended healthy lifespan in C. elegans and improved cognitive and physical function in old mice.
Strong safety record: Multiple human trials across ALS, MS, and liver disease show TUDCA is well-tolerated at doses up to 2g/day.
Multi-organ protection: Evidence for benefits in brain, muscle, liver, retina, and gut β all tissues vulnerable to aging.
β Cons
No human longevity data: Despite strong animal results, zero human trials have measured lifespan or healthspan outcomes for TUDCA.
ALS trial failure: The FDA approved then withdrew TUDCA-based Relyvrio after a Phase 3 confirmatory trial failed, raising questions about neuroprotection claims.
GI side effects: Diarrhea and abdominal discomfort are common, especially at doses above 1,000mg/day.
Cost and purity concerns: Quality TUDCA is expensive ($40-80/month), and the supplement market is unregulated β purity varies widely between brands.
What Is TUDCA?
TUDCA (tauroursodeoxycholic acid) is a bile acid β a molecule your liver makes to help digest fats. It’s formed when your body combines taurine (an amino acid) with ursodeoxycholic acid (UDCA), a bile acid that’s been FDA-approved since the 1980s for treating primary biliary cholangitis, a chronic liver disease.
TUDCA’s use in medicine dates back thousands of years to traditional Chinese medicine, where bear bile β which is naturally rich in TUDCA β was used to treat liver and eye conditions. Modern science has since synthesized it, sparing the bears, and discovered its mechanism goes far beyond bile. TUDCA crosses the blood-brain barrier and enters nearly every cell type, where it does something remarkable: it helps proteins fold correctly.
This “chemical chaperone” function is what makes TUDCA relevant to aging. As we get older, our cells’ quality control machinery β the system that ensures proteins are properly shaped and functional β begins to fail. Misfolded proteins accumulate, triggering a cellular alarm system called the unfolded protein response (UPR). When this alarm stays on too long, it drives inflammation, cellular dysfunction, and eventually cell death. TUDCA helps keep this system in balance.
How It Works
TUDCA operates through at least three distinct mechanisms, which is unusual for a single molecule:
1. Chemical Chaperone β Stabilizing Protein Folding
Inside every cell is a compartment called the endoplasmic reticulum (ER), where proteins are folded into their final three-dimensional shapes. When the ER gets overloaded β from oxidative stress, toxins, or simply the wear and tear of aging β proteins start misfolding. TUDCA binds to these vulnerable proteins and stabilizes them, preventing aggregation. In 2025, researchers at Science China identified the specific target: TUDCA binds to HSP90, a chaperone protein, and enhances its protein-refolding activity (PMID: 39327392). This is a direct, drug-like mechanism β not a vague “antioxidant effect.”
2. Mitochondrial Protection
Mitochondria, the power plants of your cells, are particularly vulnerable to aging. When they’re damaged, they release signals that trigger cell death. TUDCA stabilizes mitochondrial membranes and reduces the release of cytochrome c, a key trigger of apoptosis (programmed cell death). It also reduces reactive oxygen species (ROS) production inside mitochondria, protecting them from oxidative damage.
3. Anti-Inflammatory Signaling
Recent research (PMID: 40915187) shows TUDCA suppresses neuroinflammation by inhibiting the STING/NF-ΞΊB pathway β a central inflammatory signaling cascade. In a traumatic brain injury model, TUDCA reduced neuroinflammation and improved behavioral outcomes. This anti-inflammatory effect is separate from its protein-folding role and likely contributes to its broad tissue-protective profile.
The Longevity Connection
π₯ Lifespan Extension (Animal Evidence)
The most direct longevity evidence comes from a 2025 study in Science China Life Sciences (PMID: 39327392). Researchers found that TUDCA extended the lifespan of C. elegans (a roundworm commonly used in aging research). More importantly, when they gave oral TUDCA to old mice, the animals showed measurable improvements: better exercise capacity, stronger grip strength, and improved cognitive function.
Mechanistically, the team showed that TUDCA binds to HSP90 and enhances its protein-refolding activity β essentially restoring the protein quality control machinery that declines with age. The researchers described broad transcriptional changes consistent with anti-aging effects, meaning TUDCA shifted gene expression patterns in old mice toward a more youthful profile.
π₯ Muscle Preservation
Age-related muscle loss (sarcopenia) affects everyone β it’s why people get weaker and more frail as they age. A 2026 study in The Journal of Physiology (PMID: 42139159) showed TUDCA ameliorates age-related skeletal muscle loss. The mechanism involves improved proteostasis (protein quality control) in muscle cells, which declines with age due to chronic inflammation, hormonal changes, and reduced nutrient absorption.
π₯ Neuroprotection β The ALS Story
TUDCA’s most visible moment came through the ALS (amyotrophic lateral sclerosis) clinical trials:
The Rise: In 2020, the CENTAUR trial tested a combination of sodium phenylbutyrate and TUDCA (PB-TURSO, brand name Relyvrio) in ALS patients. The Phase 2 trial showed a statistically significant slowing of functional decline β patients on the drug declined about 25% slower than those on placebo. Based on these results, the FDA approved Relyvrio in 2022 (under the trade name Relyvrio in the US, Albrioza in Canada).
The Fall: The FDA required a confirmatory Phase 3 trial (PHOENIX). In 2024, results came in: Relyvrio failed to meet its primary endpoint. It didn’t slow disease progression any better than placebo. The manufacturer voluntarily withdrew the drug from the market. A 2026 meta-analysis (PMID: 42301686) confirmed that while PB-TURSO showed signals of benefit in some analyses, the overall evidence did not support its approval.
Importantly, the TUDCA-ALS trial β a separate Phase 3 trial testing TUDCA alone (not the combo) β also failed to show a significant benefit (PMID: 38053196). However, TUDCA appeared safe and the trial suggested possible benefit in a subgroup, keeping the door open for further research.
π₯ Multiple Sclerosis
A 2025 double-blind, placebo-controlled trial published in Med (PMID: 39447576) tested TUDCA in people with progressive multiple sclerosis. The findings: TUDCA was safe and well-tolerated, and reduced brain atrophy in a subgroup analysis. Bile acid metabolite levels in blood predicted MS progression, suggesting a real biological connection between bile acid metabolism and neurodegeneration.
π₯ Metabolic and Gut Health
An open-label 2025 trial (PMID: 40236400) tested TUDCA in patients with active ulcerative colitis. TUDCA reduced ER stress in the gut lining and was associated with reduced disease activity. This connects to the broader “gut-longevity” axis β chronic gut inflammation accelerates systemic aging.
Key Studies
| Study | Design | Key Finding |
|---|---|---|
| Shi et al., 2025 (PMID: 39327392) | Animal study (C. elegans + mice) | TUDCA extends lifespan in worms and improves exercise + cognitive function in old mice via HSP90 activation |
| Age-related muscle loss, 2026 (PMID: 42139159) | Animal study (mice) | TUDCA ameliorates age-related skeletal muscle loss by improving proteostasis |
| CENTAUR Trial, 2020 (Paganoni et al.) | Phase 2 RCT (n=137) | PB-TURSO slowed ALS functional decline by ~25%; led to FDA approval (later withdrawn) |
| PHOENIX Trial, 2024 | Phase 3 RCT (n=664) | Failed to confirm CENTAUR results; no difference vs. placebo |
| TUDCA-ALS, 2023 (PMID: 38053196) | Phase 3 RCT (TUDCA alone) | TUDCA safe but primary endpoint not met; possible subgroup benefit |
| MS Trial, 2025 (PMID: 39447576) | Phase 2 double-blind RCT | TUDCA safe in progressive MS; reduced brain atrophy in subgroup; bile acid metabolites predict progression |
| UC Trial, 2025 (PMID: 40236400) | Open-label trial | TUDCA reduces ER stress and disease activity in ulcerative colitis |
| TBI Study, 2025 (PMID: 40915187) | Animal study (mice) | TUDCA suppresses neuroinflammation via STING/NF-ΞΊB inhibition |
| Retinal Delivery, 2026 (PMID: 42497935) | Formulation study | TUDCA-modified liposomes show promise for treating age-related retinal diseases |
Dosing and Safety
Recommended Dosing
| Protocol | Daily Dose | Notes |
|---|---|---|
| General healthspan (typical supplement) | 500β1,000 mg | Split into 2 doses; take with food |
| Clinical trial dose (ALS, MS) | 1,000β2,000 mg | Used in trials; higher risk of GI side effects |
| Liver support / gut health | 500β750 mg | Standard UDCA/TUDCA dose for hepatobiliary conditions |
Form Selection
TUDCA is available as capsules or powder. Capsules (typically 250β500 mg) are preferred β TUDCA has an extremely bitter taste. Look for brands that provide third-party testing certificates, as purity varies widely. TUDCA is synthesized from UDCA, which itself is sourced from bovine bile in most cases, though synthetic routes exist.
Timing
Take TUDCA with meals containing some fat. Bile acids are released in response to dietary fat, and taking TUDCA with food improves absorption and reduces the chance of stomach discomfort.
Side Effects
| Side Effect | Frequency | Notes |
|---|---|---|
| Diarrhea / loose stools | Common (10-30%) | Most common at doses above 1,000 mg; usually resolves with dose reduction |
| Abdominal discomfort | Mild (5-15%) | Taking with food reduces this |
| Nausea | Mild (3-10%) | Typically transient |
| Headache | Uncommon (1-3%) | Reported in some clinical trials |
β Common Questions About TUDCA
What is TUDCA and how does it work?
TUDCA is a naturally occurring bile acid made when your body combines taurine with ursodeoxycholic acid. It acts as a chemical chaperone β it helps proteins fold correctly inside your cells. By binding to HSP90, a key chaperone protein, TUDCA prevents protein misfolding and reduces cellular stress. This “protein quality control” function is especially relevant to aging, since protein misfolding increases with age in every tissue.
What does the evidence actually show?
The evidence is mixed. In animals, TUDCA extends lifespan in worms and improves physical and cognitive function in old mice β those findings are solid. In humans, multiple clinical trials show TUDCA is safe and shows biological activity across different diseases. However, its biggest test β the Phase 3 PHOENIX trial for ALS β failed to show benefit, leading to the withdrawal of FDA approval for a TUDCA-containing drug. There are no human trials measuring TUDCA’s effect on healthy lifespan.
What’s the right dose?
For general healthspan purposes, most people take 500β1,000 mg per day, split into two doses and taken with meals. Clinical trials have used up to 2,000 mg/day. Start at 250β500 mg/day and increase slowly to avoid digestive side effects like diarrhea. Always take with food that contains some fat to improve absorption.
What are the risks and side effects?
The most common side effect is diarrhea, affecting roughly 10β30% of users, especially at higher doses. Other side effects include mild abdominal discomfort and nausea. TUDCA has a strong safety record overall: multiple clinical trials across ALS, MS, and liver disease found no serious safety signals at doses up to 2,000 mg/day. The main practical risk is wasting money on a low-purity product, since the supplement market is unregulated.
Who should avoid it?
People with bile duct obstruction or severe liver disease should avoid TUDCA unless prescribed by a doctor. Pregnant and breastfeeding women should not take it β there’s no safety data in these populations. Those on medications for diabetes or cholesterol (especially bile acid sequestrants) should consult their doctor, as TUDCA may interact with bile acid metabolism pathways. Anyone with chronic diarrhea or irritable bowel syndrome should start very cautiously, as TUDCA can worsen loose stools.
The Bottom Line
TUDCA is one of the more scientifically interesting supplements in the longevity space. Its mechanism β directly enhancing protein quality control by targeting HSP90 β is specific, measurable, and mechanistically linked to aging. The animal data is genuinely exciting: lifespan extension in worms plus improved function in old mice is exactly the pattern you want to see.
But TUDCA also carries a cautionary tale. The ALS story β Phase 2 positive, FDA approval, Phase 3 failure, withdrawal β is a textbook case of why early-stage results require skepticism. When the gold-standard confirmatory trial failed, the drug was pulled. This doesn’t mean TUDCA is useless; it means its neuroprotective effects in humans are either smaller than initially thought, limited to specific subgroups, or simply not strong enough to overcome a disease as aggressive as ALS.
Our verdict: TUDCA is a π₯ Silver-tier supplement. The biology is strong, the safety profile is excellent, and the animal longevity data is real. But human evidence for healthy aging remains absent. For someone optimizing their longevity protocol, TUDCA is worth considering β especially given its multi-organ protective profile and favorable safety β but it shouldn’t displace higher-evidence interventions like exercise, sleep optimization, and established supplements (creatine, omega-3s, vitamin D).
Who might benefit most: People with a family history of neurodegenerative disease, those concerned about age-related muscle loss, and individuals with metabolic or gut health issues who want a multi-targeted protective molecule. If you try it, start at 250β500 mg/day with meals, increase slowly, and track whether you notice any effects on digestion, cognitive clarity, or physical function.
Medical Disclaimer
The information on this page is for educational and informational purposes only. It is not medical advice. We are researchers, not doctors. Always consult a qualified healthcare provider before starting any supplement, especially if you are pregnant, nursing, taking medications, or have a medical condition. TUDCA affects bile acid metabolism β do not take it if you have bile duct obstruction or severe liver disease without medical supervision.
Sources
- Shi et al. “Tauroursodeoxycholic acid targets HSP90 to promote protein homeostasis and extends healthy lifespan.” Science China Life Sciences. 2025. PMID: 39327392
- “Tauroursodeoxycholic acid (TUDCA) ameliorates age-related skeletal muscle loss.” The Journal of Physiology. 2026. PMID: 42139159
- Paganoni et al. “Trial of Sodium PhenylbutyrateβTaurursodiol for Amyotrophic Lateral Sclerosis.” New England Journal of Medicine. 2020. CENTAUR Trial. PMID: 32905702
- “A randomized double-blind clinical trial on safety and efficacy of TUDCA as add-on treatment in ALS.” Trials. 2023. PMID: 38053196
- “Efficacy of Sodium Phenylbutyrate-Taurursodiol in ALS: A Systematic Review and Meta-Analysis.” Annals of Indian Academy of Neurology. 2026. PMID: 42301686
- “Bile acid metabolites predict multiple sclerosis progression and supplementation is safe in progressive disease.” Med. 2025. PMID: 39447576
- “TUDCA Reduces ER Stress and Lessens Disease Activity in Ulcerative Colitis.” medRxiv. 2025. PMID: 40236400
- “TUDCA modulates neuroinflammation via STING/NF-ΞΊB inhibition after traumatic brain injury.” International Immunopharmacology. 2025. PMID: 40915187
- “Repurposing glibenclamide for retinal protection: TUDCA-modified liposomes for ocular delivery.” International Journal of Pharmaceutics. 2026. PMID: 42497935
- “From traditional Chinese medicine to molecular oncology β pleiotropic effects of TUDCA.” Klinicka Onkologie. 2025. PMID: 40962506
- “Combination Supplement Therapy in Neurodegenerative Diseases.” The Journal of Nutrition. 2025. PMID: 40675338
- “Sodium Phenylbutyrate and Taurursodiol: A Story of Hope Turned to Disappointment in ALS Treatment.” Clinical Drug Investigation. 2024. PMID: 38909349