Milk thistle vs TUDCA
The two great liver supplements, and the same lesson twice: the evidence people quote for each belongs to something you are not actually buying.
Milk thistle
Silymarin, silibinin, silybin, Silybum marianum
The pooled liver-related mortality benefit (RR 0.50) is not significant once only the high-quality trials are counted (RR 0.57, 95% CI 0.28–1.19), and the best-designed randomized trial found nothing at above-label doses. The respected mushroom-antidote use is intravenous silibinin, not the capsule.
Full Milk thistle evidence reviewTUDCA
Tauroursodeoxycholic acid
Real bile-acid chaperone biology with genuine human trial engagement — it was the active component of AMX0035/Relyvrio, which showed a positive phase 2 signal in ALS before its confirmatory phase 3 failed and the drug was withdrawn. The liver/ER-stress mechanism is solid; the clinical outcome record is now a cautionary tale, not a green light.
Full TUDCA evidence reviewSide by side
| Milk thistle | TUDCA | |
|---|---|---|
| Marketed for | Liver support and 'detox', hangover protection, blood sugar | Liver health, ER-stress reduction, neuroprotection |
| Evidence grade | Clinical data | Clinical data |
| Family | mTOR & other | mTOR & other |
| Key human source | Cochrane review, 18 RCTs / 1,088 patients, 2007 | AMX0035 phase 2/3 ALS trial, NEJM 2020 |
marks a row where the two differ. Evidence grades come from our evidence matrix, which grades each molecule on the human data for the use it is marketed for.
Our verdict
Neither supports the liver-support claim it is sold on, and both fail in the same instructive way — by borrowing credibility from a relative. Milk thistle's pooled liver-related mortality benefit (RR 0.50) stops being significant once only the high-quality trials are counted, its best-designed randomized trial found nothing at above-label doses, and the mushroom-poisoning use everyone cites is intravenous silibinin given in hospital, not a capsule. TUDCA's borrowed credibility is its parent compound: it is UDCA, not TUDCA, that became an approved drug with randomized-trial support in primary biliary cholangitis, and TUDCA's own most ambitious human program — the ALS combination Relyvrio — failed phase 3 and was withdrawn in 2024. Milk thistle has the larger trial base and the clearer null; TUDCA has the better mechanism and the more serious drug behind it.
Milk thistle fits if
You want the cheaper, older option with the larger randomized literature behind it — as long as you read that literature as the null it mostly is, and not as the intravenous antidote.
TUDCA fits if
The ER-stress mechanism is what interests you, and you understand the strong liver evidence belongs to UDCA, the approved parent drug, rather than to the supplement in the bottle.