Supplement analysis backed by scientific evidence · PT

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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.

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.

Scientific references

Where to buy

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

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