The Longevity Series — Guides
TUDCA vs Ox Bile: What's the Difference?
Last updated 19 August 2026
Both are bile-related supplements, but they are not interchangeable. Here's what each one actually is — and an honest note on where the neuroprotective hype around TUDCA actually stands.
What is TUDCA?
TUDCA (tauroursodeoxycholic acid) is a single, specific bile acid — a taurine conjugate of ursodeoxycholic acid. It occurs naturally in the body in small amounts and is produced for supplements by synthesis. Because it is one defined molecule, TUDCA products are dosed precisely, typically 250–1000mg per serving. See our TUDCA 1100mg Capsules.
What the human research actually shows
TUDCA's strongest evidence base is in liver disease, where it is used as a licensed medicine (not a supplement) in some countries. Its wider reputation — particularly for neurological support — largely traces back to a smaller Phase 2b trial in ALS patients, which reported a roughly 7-point-per-year slower decline on a standard disability scale when added to the standard drug riluzole.1 That result led to a large, multi-country Phase 3 trial (TUDCA-ALS) designed to confirm it properly.
Reported in 2025, the Phase 3 trial did not meet its primary endpoint — TUDCA did not distinguish itself from placebo in slowing ALS progression, and no meaningful differences were seen in survival time or biomarkers either.2 This is a genuinely important update: a promising smaller trial did not hold up under a larger, better-controlled one. It doesn't mean TUDCA has no role — its liver-related use is separately well-established — but the wider neuroprotective narrative built on the earlier ALS data should be treated with real caution.
What is ox bile?
Ox bile is desiccated whole bile — a natural mixture of many bile acids, salts and compounds, standardised by weight rather than by a single molecule. Bile's physiological job is emulsifying dietary fat, which is why ox bile is traditionally taken with fatty meals. Ox bile has a much smaller published human trial base than TUDCA — most of its supplement use is traditional rather than clinically established. See our Ox Bile 1000mg Capsules.
Side by side
| TUDCA | Ox bile | |
|---|---|---|
| What it is | One specific bile acid | Whole desiccated bile — a natural mixture |
| Source | Synthesised | Bovine |
| Composition | Precisely defined | Broad spectrum of bile salts |
| Vegan/vegetarian | Suitable (check capsule shell) | Not suitable — animal-derived |
| Typical use | Daily, with food | With fat-containing meals |
| Price | Higher | Lower |
Which should you choose?
TUDCA if you want a single, precisely dosed bile acid — it is the form the modern supplement literature focuses on, and the choice for vegetarians. Ox bile if you want the traditional, full-spectrum option taken alongside fatty meals at a lower price. They are different tools; pick based on what you're after, and follow the label of whichever you choose.
Shop gut health & digestion supplements →Frequently asked questions
Is TUDCA vegan?
Supplement TUDCA is synthesised rather than animal-extracted, so it is generally suitable for vegetarians and vegans — check the capsule shell on any given product. Ox bile is animal-derived.
Can I take TUDCA and ox bile together?
They overlap in function. Choose one and follow its label; do not stack bile supplements without speaking to your doctor.
Who should not take bile supplements?
Not suitable for under-18s or for women who are pregnant or breastfeeding. If you have a medical condition — particularly anything relating to the liver, gallbladder or digestion — or take medication, speak to your doctor before use.
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- Proof-of-concept Phase IIb study of TUDCA added to riluzole in ALS — reported a slower rate of functional decline compared with riluzole alone.
- TUDCA-ALS Phase 3 randomised, multi-country trial (NCT03800524) — did not meet its primary endpoint on the ALS Functional Rating Scale-Revised; no significant differences in survival or biomarkers vs placebo.
This guide is for general information only and does not constitute medical advice. These products are food supplements, not medicines — they are not intended to diagnose, treat, cure or prevent any disease.