TUDCA vs. Milk Thistle: Which Is the King of Liver Protection?

Last updated: November 1, 2026 · Originally published: January 24, 2026 · By Eternal Elixir Editorial

Quick answer: TUDCA and milk thistle support the liver in different ways. TUDCA is a bile acid that adds to the bile acids your liver already makes, so it is the better fit if healthy bile flow and the digestion of fatty meals are what you want to support. Milk thistle is a herbal extract whose active compounds, known together as silymarin, work mainly as antioxidants. It costs less per day, but the body clears it quickly. For most people weighing up TUDCA vs milk thistle for liver support, our pick is Eternal Elixir TUDCA 500mg: 500mg per capsule, one capsule a day, and 90 capsules for $59.99, which is $0.67 a day.

Eternal Elixir makes TUDCA 500mg, and it is our pick in this comparison. We do not sell milk thistle. Every competitor price and dose below comes from the retailer or brand page we link, checked in September 2026, and every research claim links to the published study so you can check it yourself.

TUDCA vs milk thistle: the short answer

TUDCA and milk thistle are often mentioned in the same breath, but they come from different places and act on different parts of liver function. That difference is also why many people take TUDCA and milk thistle together.

• TUDCA (tauroursodeoxycholic acid) is a bile acid. Your liver attaches bile acids to the amino acids taurine or glycine before it releases them into bile, and TUDCA is the taurine-bound form of ursodeoxycholic acid (UDCA). As a supplement, it joins the pool of bile acids your body already recycles.
• Milk thistle (Silybum marianum, also sold in Australia as St Mary’s thistle) is a herb. Its seeds contain silymarin, a mix of plant compounds called flavonolignans, including silybin, isosilybin, silychristin and silydianin. Silymarin acts mainly as an antioxidant.

So the choice comes down to your goal. If bile flow and fat digestion are your focus, TUDCA is the more direct option. If you want a cheap antioxidant herb from the pharmacy shelf and you are comfortable with modest expectations, milk thistle costs less. Neither has strong evidence in healthy adults, and the research section below sets out exactly what has and hasn’t been shown.

What is TUDCA and what is it used for?

TUDCA is a water-soluble bile acid. Bile acids are made in the liver from cholesterol, stored in the gallbladder and released into the gut when you eat, where they help you absorb dietary fat and the fat-soluble vitamins. Most of them are then taken back up and returned to the liver, so your body reuses the same pool many times a day.

TUDCA and UDCA are among the most water-soluble bile acids. Italian researchers described TUDCA as “a highly hydrophilic bile acid” in a 1996 trial, and that property is the reason scientists have studied it for liver and bile support for decades. In cell and animal work, TUDCA also acts as a “chemical chaperone” that helps cells fold proteins properly, which is where the claims about endoplasmic reticulum (ER) stress come from. As you will see below, that effect has not been confirmed in the one human trial that looked for it.

People take a TUDCA supplement to support healthy bile flow and normal liver function. It is popular with people who train hard, eat a lot of rich food, or take several supplements and want to look after their liver while they do. Our guide to the benefits of a TUDCA supplement goes through each of these uses in more detail, and TUDCA for athletes covers the training side. If you want the chemistry, our explainer on TUDCA vs UDCA compares the two bile acids molecule by molecule.

What is milk thistle?

Milk thistle is a spiky, purple-flowered plant in the daisy family, and it has a long history as a traditional liver herb. It is widely stocked in Australian pharmacies. Supplements are made from an extract of the seeds, and labels usually give the extract amount plus the weight of dried fruit or seed it was made from. That is why you see figures like 35,000mg on the front of the pack.

The front-of-pack figure is the weight of plant material, not the amount of active compound. The more useful number is the silymarin content per tablet (some labels say “flavanolignans calculated as silybin”), and not every brand prints it. Of the three pharmacy brands in our table, Blackmores and Herbs of Gold state it, while the Swisse listing at Chemist Warehouse does not.

The main weakness of milk thistle is how quickly the body processes it. In a pharmacokinetic study at the University of North Carolina, three healthy volunteers took a single 600mg dose of standardised milk thistle extract. The silymarin compounds were cleared fast, with half-lives of one to three hours for the free forms. Near peak blood levels, only about 17% of the silymarin in circulation was in its free form, and the rest had already been converted by the body into other compounds (Wen et al., 2008).

TUDCA vs milk thistle side by side

TUDCA and milk thistle products in Australia compared

These are the products we checked in September 2026. We list three TUDCA supplements and three milk thistle supplements that Australians can buy locally or with local delivery. Cost per day uses each label’s own daily serve. Chemist Warehouse prices change with its promotions, so we show the RRP where the listing gave one.

Add TUDCA 500mg to cart · $59.99

All three TUDCA products give 500mg per capsule, so the difference is bottle size and price. Our bottle holds 45 g of TUDCA for $59.99, which is $1.33 per gram. OHC Longevity’s bottle holds 30 g for $89.99 ($3.00 per gram), and the Nutricost bottle holds 15 g for $48.99 ($3.27 per gram). Ninety days of Nutricost at one capsule a day takes three bottles, which comes to $146.97 against $59.99 for one bottle of ours. Nutricost does cost less up front, so it is the cheaper way to try TUDCA for a single month.

Milk thistle is cheaper than TUDCA across the board. Swisse at its Chemist Warehouse promotional price has the lowest cost per day in the table, and at its RRP it is $0.67 a day. Blackmores works out at $1.71 a day at RRP because its label asks for three tablets a day. The Herbs of Gold figure is a sale price on the brand’s own site, and at the regular $47.45 it is $0.79 a day. Of the three, Herbs of Gold states the most active compound per tablet.

If you were hoping to pick up TUDCA at the pharmacy, Chemist Warehouse’s website listed no TUDCA supplement when we searched it in September 2026. Our page on TUDCA at Chemist Warehouse explains where Australians buy it instead, and our comparison of the best TUDCA supplements in Australia covers more brands than we have room for here.

What the human research shows, and what it doesn’t

Both ingredients are sold with big promises, so here is what the published human trials actually found. We have left out the mouse and cell studies that most TUDCA marketing relies on, because results in animals do not tell you what happens in people.

TUDCA: the human trials

Four weeks, 20 adults, insulin sensitivity. In a 2010 trial at Washington University in St Louis, 20 adults with an average body-mass index of 37 were randomised to 1,750mg of TUDCA a day or a placebo for four weeks. Insulin sensitivity in the liver and muscle rose by about 30% in the TUDCA group and did not change in the placebo group. Markers of ER stress in muscle and fat tissue did not change in either group (Kars et al., 2010). Two cautions apply. It was a small, short trial, and the dose was three and a half times what one of our capsules provides.

Trials under medical care. Most other TUDCA trials enrolled people with a diagnosed bile-duct condition who were under specialist care. In a six-month Italian trial of 24 such patients, daily doses of 500mg, 1,000mg and 1,500mg were compared, and diarrhoea was the only side effect reported (Crosignani et al., 1996). A larger 24-week trial in China gave 199 patients either 250mg of TUDCA or 250mg of the prescription bile acid UDCA three times a day. The two performed similarly on liver blood tests, and side-effect rates were comparable (Ma et al., 2016). These trials tell us TUDCA was well tolerated at 500mg to 1,500mg a day for up to six months in people who were diagnosed and medically supervised. They do not show a benefit for healthy people, and a supplement is no substitute for that kind of care.

Milk thistle: the human trials

The largest placebo-controlled trial. A 2012 US trial gave 154 adults with a diagnosed long-term liver condition either 420mg or 700mg of silymarin three times a day, or a placebo, for 24 weeks. Neither dose did better than placebo on the main liver enzyme measure, and side effects were similar to placebo (Fried et al., 2012).

The most encouraging trial. In a 48-week Malaysian trial, 99 adults with a diagnosed liver condition took 700mg of silymarin or a placebo three times a day. It missed its main target, although a secondary measure on repeat liver biopsy favoured silymarin, and the authors said a larger trial is needed to confirm it. Silymarin was well tolerated (Wah Kheong et al., 2017).

Those trials used 1,260mg to 2,100mg of silymarin a day. Three Blackmores tablets give 165mg a day, so the doses on pharmacy labels are far below the doses that were tested.

What hasn’t been shown

• We found no published trial that compares TUDCA with milk thistle directly, in any group of people.
• No trial has shown that either one improves liver health in healthy adults.
• The ER stress effect of TUDCA comes from cell and animal studies. The only human trial that measured it, in muscle and fat tissue, found no change.
• No trial has tested how long either takes to produce an effect you can feel.

Our view is that TUDCA has the clearer rationale for bile support, because it is a bile acid, and it has the one positive trial on a metabolic measure. Milk thistle has more trials in total, and the best of them were neutral or mixed. Anyone with a diagnosed liver or gallbladder condition should speak to their doctor rather than choose between supplements.

TUDCA side effects, and who shouldn’t take it

In the trials that reported side effects, TUDCA was well tolerated, and diarrhoea was the only side effect reported in the dose-ranging trial. Our label directions are one 500mg capsule a day with a meal, which is a lower daily dose than any of the trials used. Our page on TUDCA side effects goes through the full safety data, and the TUDCA dosage guide covers timing and how long people take it.

Do not take TUDCA without speaking to your doctor first if any of these apply to you:

• you are pregnant or breastfeeding, because there is no safety research in these groups
• you are under 18
• you have a diagnosed liver, gallbladder or bile-duct condition
• you take prescription medicines, especially bile acid binders such as cholestyramine, which can bind bile acids in the gut (ask your pharmacist about timing).

Milk thistle has its own cautions. The Swisse label says not to use it if you are pregnant or likely to become pregnant. The Blackmores label says to talk to a health professional first if you are pregnant or breastfeeding, have a pre-existing condition or take medicines, and notes that some products should be stopped at least two weeks before elective surgery. Milk thistle belongs to the daisy family, so people allergic to plants such as ragweed, chrysanthemums or marigolds should avoid it unless their doctor says otherwise.

Can you take TUDCA and milk thistle together?

Yes, many people do. They work through different routes, since TUDCA adds to the bile acid pool and silymarin acts as an antioxidant, so taking TUDCA and milk thistle together doubles up on nothing. We found no reported interaction between them. Some imported products even combine the two in one capsule, and if you buy one of those, check how much of each ingredient a serve contains.

The practical argument for starting with one is clarity. If you begin two supplements in the same week and something changes, you cannot tell which one did it. Start with the one that matches your goal, take it consistently for 8 to 12 weeks, and add the second only if you still want to. Running both from our table costs about $1.30 a day, for example, with one Eternal Elixir TUDCA capsule and one Herbs of Gold tablet at its sale price. If you take prescription medicines, ask your pharmacist before combining supplements.

Where NAC fits: TUDCA vs milk thistle vs NAC

NAC (N-acetylcysteine) is the third name that comes up in liver-support searches. It works on a different pathway again. NAC supplies cysteine, the amino acid your cells need to make glutathione, one of the body’s main antioxidants. So TUDCA works through bile acids, milk thistle through plant antioxidants, and NAC through your own glutathione supply.

We compare all three in our TUDCA vs NAC vs milk thistle verdict, and the two-way TUDCA vs NAC comparison goes deeper on that pairing. If antioxidant support is your main interest, glutathione vs NAC and our list of the best glutathione supplements in Australia are the better starting points.

Who should choose TUDCA, and who should choose milk thistle

TUDCA suits you if:

• your main interest is supporting bile flow and the digestion of fatty meals
• you want one capsule a day rather than three tablets
• you would rather pay more per day for a bile acid than less for a herb.

TUDCA doesn’t suit you if:

• you are pregnant, breastfeeding or under 18
• you have a diagnosed liver, gallbladder or bile-duct condition and have not spoken to your doctor
• your budget is tight and you want the lowest cost per day.

Milk thistle suits you if:

• you want a low-cost herbal antioxidant you can buy at any pharmacy
• you are happy with a traditional product that has a long safety record at label doses.

Milk thistle doesn’t suit you if:

• you are allergic to daisy-family plants
• you are pregnant or trying to become pregnant (see the Swisse label warning above)
• you specifically want bile acid support, which silymarin does not provide.

If you are not sure your liver needs attention at all, read signs your liver needs support first, and see your GP for a blood test if something feels wrong.

Why Eternal Elixir TUDCA 500mg is our pick

Our TUDCA wins this comparison on facts you can check on the label and the product page:

• 500mg per capsule. One capsule a day with a meal is the full label serve, so there is no doubling up.
• 90 capsules per bottle. That is a 90-day supply, three times the 30 capsules in a Nutricost bottle and half as much again as OHC Longevity’s 60.
• $0.67 a day. At $59.99 a bottle, that is the lowest cost per day of the three TUDCA products in our table, and $1.33 per gram of TUDCA.
• Multi-bottle savings. Two bottles save 10% ($107.98), three save 15% ($152.97) and five save 20% ($239.96). At three bottles the cost falls to $0.57 a day, and at five it is $0.53.
• Delivery. Orders are dispatched in 1 business day, orders over $100 ship free (two bottles qualify), and every order carries a 30-day money-back guarantee, with Afterpay available.

What we won’t claim: we have not run a trial of our own product, and the research above was done with TUDCA in general, not with any one brand. The case for our bottle rests on the dose per capsule, the size of the bottle and the price per day.

Building a liver-support routine around TUDCA

If you want to support your liver and metabolism with more than one ingredient, our Metabolic Wellness Stack combines TUDCA 500mg with Berberine 500mg and Reduced L-Glutathione 2000mg for $126.99, which is $22.98 less than buying the three separately. It already includes a bottle of TUDCA, so choose either the stack or a TUDCA bottle, not both. Read our guide to the best berberine supplements in Australia before you add berberine, since berberine can interact with some prescription medicines and suits a different goal.

For a wider view of the category, our roundup of the best liver support supplements in Australia compares TUDCA, milk thistle, NAC and glutathione products in one place. Our article on TUDCA and gut health covers the link between bile acids and the gut, and if you are comparing brands, our list of Double Wood TUDCA alternatives covers the imported options. Readers who take TUDCA as part of a healthy-ageing routine can see how it fits with NMN and resveratrol in our longevity stack guide, our comparison of the best NMN supplements in Australia and our Trans-Resveratrol 1200mg capsules. You can also browse our full range.

Frequently asked questions

Can you take TUDCA and milk thistle together?

Yes. TUDCA adds to your bile acid pool and milk thistle’s silymarin acts as an antioxidant, so the two work through different routes and we found no reported interaction between them. Start one at a time so you can tell what each is doing, and ask your pharmacist first if you take prescription medicines.

Add TUDCA 500mg to cart · $59.99

Is TUDCA the same as milk thistle?

No. TUDCA is a bile acid, the taurine-bound form of UDCA, while milk thistle is a herb whose seed extract contains the antioxidant compounds known as silymarin. They are sometimes sold in the same capsule, but they are different substances that act in different ways.

Is TUDCA better than milk thistle for the liver?

It depends on what you want to support. TUDCA is the more direct choice for bile flow and fat digestion because it is itself a bile acid, and it has one positive human trial on insulin sensitivity. Milk thistle costs less and has more trials overall, but its larger trials were neutral or mixed. For most people comparing TUDCA or milk thistle for liver support, we recommend TUDCA, and our pick is Eternal Elixir TUDCA 500mg.

What is better than milk thistle for your liver?

For most adults, the habits that matter most are drinking less alcohol, keeping a healthy weight, staying active and eating plenty of vegetables and fibre. Among supplements, TUDCA works through the bile acid pool, which milk thistle does not touch, and NAC supports your body’s own glutathione. No supplement replaces a check-up with your GP if you are worried about your liver.

What can TUDCA do for the liver, and what hasn’t been shown?

TUDCA is a bile acid, so it supports healthy bile flow and normal liver function as part of the bile acid pool. In a four-week trial of 20 adults, 1,750mg a day raised liver and muscle insulin sensitivity by about 30%. What hasn’t been shown is any benefit for liver health in healthy adults, and the ER stress effect seen in lab studies was not found in the one human trial that measured it.

What are the side effects of TUDCA?

TUDCA was well tolerated in the trials that reported side effects, at 500mg to 1,500mg a day. Diarrhoea was the only side effect reported in a six-month trial of 24 patients, and a 24-week trial of 199 patients found side-effect rates similar to the prescription bile acid UDCA. Take it with a meal, follow the label dose and stop if your stomach does not agree with it.

Who shouldn’t take TUDCA?

Do not take TUDCA if you are pregnant, breastfeeding or under 18. Speak to your doctor first if you have a diagnosed liver, gallbladder or bile-duct condition, or if you take prescription medicines, particularly bile acid binders such as cholestyramine.

Can you buy TUDCA at Chemist Warehouse?

Not when we checked. Chemist Warehouse’s website listed no TUDCA supplement in September 2026, although it stocks several milk thistle products. Australians usually buy TUDCA online from specialist brands, and ours is dispatched in 1 business day.

How much milk thistle should I take?

Follow the label on the product you buy, because doses differ between brands. Herbs of Gold and Swisse ask for one tablet a day, and Blackmores asks for one tablet three times a day with food, which gives 165mg of silymarin. The trials that used 420mg or 700mg of silymarin three times a day were run under medical supervision.

How long does TUDCA take to work?

No trial has measured how long it takes to notice an effect. The insulin sensitivity trial measured its result after four weeks at a much higher dose than one capsule. We suggest judging TUDCA over 8 to 12 weeks of daily use, one supplement change at a time.

Which TUDCA supplement do we recommend?

Our pick is Eternal Elixir TUDCA 500mg, which we make. It has 500mg per capsule and 90 capsules per bottle, and at $59.99 it works out at $0.67 a day, the lowest cost per day of the TUDCA products we compared. OHC Longevity also offers 500mg per capsule in a 60-capsule bottle, and Nutricost is the cheapest bottle up front at $48.99 for 30 capsules.

Add TUDCA 500mg to cart · $59.99

The verdict

TUDCA vs milk thistle comes down to the job you want done. Milk thistle is the cheaper herbal antioxidant, and at pharmacy promotional prices it costs as little as $0.28 a day. TUDCA is a bile acid, which makes it the more direct way to support healthy bile flow and fat digestion, and it has the one positive human trial on a metabolic measure. Neither has been shown to improve liver health in healthy adults, and anyone with a diagnosed liver condition should be guided by their doctor.

If you have decided on TUDCA, our pick is Eternal Elixir TUDCA 500mg: the same 500mg per capsule as the other TUDCA products in our table, in a 90-capsule bottle that costs $0.67 a day and ships from Sydney.

Sources

• Kars M, Yang L, Gregor MF, et al. Tauroursodeoxycholic acid may improve liver and muscle but not adipose tissue insulin sensitivity in obese men and women. Diabetes. 2010;59(8):1899-1905. PubMed 20522594
• Crosignani A, Battezzati PM, Setchell KD, et al. Tauroursodeoxycholic acid for treatment of primary biliary cirrhosis: a dose-response study. Digestive Diseases and Sciences. 1996;41(4):809-815. PubMed 8674405
• Ma H, Zeng M, Han Y, et al. A multicenter, randomized, double-blind trial comparing the efficacy and safety of TUDCA and UDCA in Chinese patients with primary biliary cholangitis. Medicine (Baltimore). 2016;95(47):e5391. PubMed 27893675
• Wen Z, Dumas TE, Schrieber SJ, et al. Pharmacokinetics and metabolic profile of free, conjugated, and total silymarin flavonolignans in human plasma after oral administration of milk thistle extract. Drug Metabolism and Disposition. 2008;36(1):65-72. PubMed 17913795
• Fried MW, Navarro VJ, Afdhal N, et al. Effect of silymarin (milk thistle) on liver disease in patients with chronic hepatitis C unsuccessfully treated with interferon therapy: a randomized controlled trial. JAMA. 2012;308(3):274-282. PubMed 22797645
• Wah Kheong C, Nik Mustapha NR, Mahadeva S. A randomized trial of silymarin for the treatment of nonalcoholic steatohepatitis. Clinical Gastroenterology and Hepatology. 2017;15(12):1940-1949. PubMed 28419855
• Product details and prices, checked September 2026: Eternal Elixir TUDCA 500mg, OHC Longevity TUDCA, Nutricost TUDCA 500mg (iHerb AU), Herbs of Gold St Mary’s Thistle 35,000, Blackmores Milk Thistle 42 tablets, Swisse Milk Thistle 35000mg 60 tablets.