Limited evidenceGeneral health

TUDCA (Tauroursodeoxycholic Acid)

TUDCA is a bile acid with genuinely interesting mechanistic biology (ER-stress reduction, bile flow) and almost no confirmatory human outcome data. Its highest-profile test — the phenylbutyrate/taurursodiol combination in ALS — succeeded in a phase 2 trial and then failed decisively in the phase 3 PHOENIX trial, leading to the product's withdrawal from the US market in 2024.

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What the science says

Slows progression of ALS (as PB/TUDCA) Limited evidence
The phase 2 CENTAUR trial of sodium phenylbutyrate plus taurursodiol reported a slower decline in ALSFRS-R and, in extension analyses, longer tracheostomy/ventilation-free survival. The larger phase 3 PHOENIX trial did not confirm any functional or survival benefit, and the sponsor withdrew Relyvrio/Albrioza from the market in 2024. Reviews of the episode describe it as hope turned to disappointment; TUDCA alone has never been shown to change ALS outcomes.
Improves insulin sensitivity Limited evidence
A randomized study in obese adults found four weeks of TUDCA 1,750 mg/day improved hepatic and muscle insulin sensitivity by roughly 30% on clamp measures, but did not improve adipose tissue insulin sensitivity or markers of ER stress. The sample was about 20 participants and the finding has not been replicated in a larger trial.
Protects the liver / improves cholestasis Limited evidence
TUDCA is a taurine conjugate of ursodeoxycholic acid (UDCA), a licensed drug for primary biliary cholangitis. Small comparative studies suggest TUDCA lowers liver enzymes similarly to UDCA with possibly better tolerability, but there are no outcome trials, and clinical guidelines recommend UDCA, not TUDCA. Using TUDCA as "on-cycle liver support" for anabolic steroids has no supporting evidence.
Neuroprotection and retinal protection Limited evidence
Rodent and cell models show TUDCA reduces apoptosis in models of Huntington's disease, Parkinson's disease and retinitis pigmentosa. None of this has been tested in adequately powered human trials.

Dosage & safety

Studied doseHuman studies have used 1,000-1,750 mg/day in divided doses for 4 weeks (metabolic endpoints) and 1 g/day within the ALS combination product; supplement labels commonly suggest 250-500 mg once or twice daily, a dose below anything tested against a clinical endpoint. Bile acids are best taken with food.

SafetyShort-term trials report mild diarrhea, nausea and abdominal discomfort as the main effects; the PB/TUDCA combination caused notably more gastrointestinal adverse events than placebo. Long-term safety in healthy people is unknown. Bile acid sequestrants (cholestyramine, colesevelam) and aluminium antacids bind it and reduce absorption. Contraindicated in complete biliary obstruction; use caution in gallstone disease. In some countries TUDCA is regulated as a medicine rather than a supplement (it is licensed as a drug in parts of Europe and Asia), so legal status varies. Not recommended in pregnancy without specialist supervision.

How to take it

TimingSplit across the day with meals.

With food?With food — bile acids are absorbed alongside a meal, which is when they are physiologically released anyway.

Worth knowingLabel doses of 250-500 mg sit well below the 1,000-1,750 mg/day actually tested, so a cheap bottle is usually a subtherapeutic gesture.

Interactions

With medications

bile acid sequestrants (cholestyramine, colesevelam, colestipol)
They bind TUDCA in the gut and prevent absorption. separate by at least 4 hours
aluminium-containing antacids
They bind bile acids and reduce absorption. separate by at least 2 hours

Well-established interactions only — this is not a complete list. Always tell your doctor and pharmacist what you take.

Frequently asked questions

Does TUDCA help ALS?

No — the phenylbutyrate-TUDCA combination looked promising in a phase 2 trial but failed in the phase 3 PHOENIX trial and was withdrawn from the US market in 2024. TUDCA alone has never been shown to change ALS outcomes.

Does TUDCA protect the liver on steroids or cycles?

There is no supporting evidence for TUDCA as 'on-cycle liver support' for anabolic steroids. For cholestatic liver disease, guidelines recommend the licensed drug UDCA, not TUDCA.

How much TUDCA should I take?

Human studies used TUDCA at 1,000-1,750 mg/day in divided doses with food. Label doses of 250-500 mg sit well below anything tested against a clinical endpoint.

Does TUDCA improve insulin sensitivity?

The evidence is limited to one small study of about 20 obese adults, where TUDCA at 1,750 mg/day for four weeks improved liver and muscle insulin sensitivity by roughly 30%. It has not been replicated in a larger trial.

Scientific references

Tauroursodeoxycholic Acid may improve liver and muscle but not adipose tissue insulin sensitivity in obese men and women
Kars M, Yang L, Gregor MF, Mohammed BS, Pietka TA, Finck BN, et al — Diabetes, 2010
Long-term survival of participants in the CENTAUR trial of sodium phenylbutyrate-taurursodiol in amyotrophic lateral sclerosis
Paganoni S, Hendrix S, Dickson SP, Knowlton N, Macklin EA, Berry JD, et al — Muscle Nerve, 2021
Sodium Phenylbutyrate and Tauroursodeoxycholic Acid: A Story of Hope Turned to Disappointment in Amyotrophic Lateral Sclerosis Treatment
Ketabforoush A, Wang JF, Yazdani M, Chaibakhsh S, Ariaei A, Alavi Zaringhalam S, et al — Clin Drug Investig, 2024

Where to buy

Double Wood Supplements, Tudca, 60 Capsules (250 mg per Capsule)

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