The Bile Acid Breakdown: TUDCA vs. UDCA: Understanding the Chemical Differences for Optimal Liver Health

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

Quick answer: TUDCA is UDCA with a molecule of taurine attached. UDCA (ursodeoxycholic acid) is a bile acid that gut bacteria make, and doctors use it as a medicine for certain liver and gallbladder conditions. TUDCA (tauroursodeoxycholic acid) is its taurine-bound form: more water-soluble, and sold in Australia as a supplement. Only one trial has compared them head to head, in 199 patients under specialist care, and at 750mg a day for 24 weeks the two gave similar results on liver blood tests with similar side-effect rates. No trial has compared them in healthy people. If you want TUDCA for general liver and bile support, our pick is Eternal Elixir TUDCA 500mg: 90 capsules, one a day with a meal, about $0.67 a day. If a doctor has prescribed you UDCA, don’t swap it for a supplement.

Eternal Elixir makes TUDCA 500mg, and it is our pick. This guide starts with the bile acid breakdown: what bile acids are, where UDCA and TUDCA come from, and the single chemical difference between them. Then it covers what the human trials found, how TUDCA products sold in Australia compare on price per 500mg, and who should use which. Every study we mention is listed in the sources at the end.

The bile acid breakdown: what bile acids do

Bile acids are made in the liver from cholesterol. The two main ones the liver makes, called primary bile acids, are cholic acid and chenodeoxycholic acid (CDCA). Straight after it makes them, the liver joins them to one of two amino acids, glycine or taurine, which gives the “glyco” and “tauro” forms you see in chemical names (Chen and Cassaro, StatPearls).

Bile is stored in the gallbladder and released into the small intestine when you eat. There, bile acids act like a detergent: they break large fat droplets into tiny particles called micelles so that digestive enzymes can reach the fat. Most bile acids are then absorbed again at the end of the small intestine and carried back to the liver to be reused. The rest pass into the large bowel, where bacteria convert some of them into secondary bile acids such as deoxycholic and lithocholic acid (Chen and Cassaro, StatPearls).

Where UDCA and TUDCA come from

UDCA is one of those secondary bile acids. It is made only by gut bacteria, and in people UDCA and its conjugated forms make up about 2% of the bile acid pool. In bear bile they make up more than 50%, and bear bile has been used in traditional Chinese medicine for about 3,000 years (Vang 2014).

TUDCA is the taurine conjugate of UDCA: the same bile acid backbone, with taurine joined to its side chain. Because the liver joins bile acids to taurine, your body makes small amounts of TUDCA itself.

TUDCA vs UDCA: the chemical difference

The taurine group changes how the molecule behaves in water. UDCA is already described as a hydrophilic (water-friendly) bile acid, unlike the more hydrophobic bile acids that can damage liver cells, and TUDCA is more hydrophilic again (Vang 2014; Ma 2016). In the lab and in animals, TUDCA also acts as a “chemical chaperone” that helps cells cope with stress in the endoplasmic reticulum, where proteins are folded (Kars 2010). Whether that happens in people is less clear: in the one human trial that checked, markers of that stress in muscle and fat did not change.

What the human trials found

TUDCA vs UDCA head to head

The only direct comparison is a multicentre, double-blind trial in China (Ma 2016). It randomised 199 patients who were being treated for a chronic liver condition to 250mg of TUDCA or 250mg of UDCA three times a day, 750mg a day in total, for 24 weeks.

• The main target was a fall of more than 25% in the liver enzyme ALP. It was reached by 76% of the TUDCA group and 81% of the UDCA group, a difference small enough to be chance.
• Both groups improved by a similar amount on the other liver blood tests.
• Itching became more common on UDCA (from 1.4% to 10% of patients) and did not change on TUDCA.
• Side-effect rates were similar in the two groups.

That is useful for knowing the two behave alike in the body. It does not tell a healthy person what TUDCA does for them, because everyone in the trial was a patient under specialist care.

TUDCA in people without a liver condition

The trials of TUDCA outside medical care are small and short:

• Kars 2010. 20 adults with a high body weight (average BMI 37) took 1,750mg of TUDCA a day or a placebo for 4 weeks. On TUDCA, insulin sensitivity in the liver and muscle rose by about 30% and did not change on placebo. Markers of cell stress in muscle and fat tissue did not change.
• Walsh 2016. 12 young healthy adults took a single 1,500mg dose of TUDCA or a placebo before a sugary drink. On placebo, blood vessel widening in the arm (a measure of blood vessel function) fell by 32% an hour after the drink. On TUDCA it barely changed.

Both used doses higher than one 500mg capsule, and neither ran longer than a month. There are no long-term trials of TUDCA in healthy people. Our guide to the benefits of TUDCA covers these studies in more detail, and our article on TUDCA and gut health looks at the bile and microbiome research.

Which one should you use?

• If a doctor has prescribed UDCA, keep taking it as prescribed. Don’t replace it with TUDCA or add TUDCA on top without asking your doctor, because the two act in similar ways.
• If you are healthy and want general liver and bile support, TUDCA is the one sold as a supplement in Australia. Keep your expectations in line with the evidence above: small, short trials, mostly at higher doses.
• If you have symptoms such as yellowing skin, dark urine, pale stools or pain under the right ribs, see your GP. Those need a medical assessment, not a supplement.

Do not take TUDCA if you are pregnant or breastfeeding or under 18, and talk to your GP or pharmacist first if you take any prescription medicine. Our TUDCA side effects guide covers what has been reported. One Australian retailer’s TUDCA page lists stomach discomfort, diarrhoea, bloating and changes in bowel movements as possible effects, particularly on an empty stomach, and our label says to take it with a meal.

TUDCA in Australia: price per 500mg (as of Sep 2026)

We took each price, capsule strength and serve from the seller’s own page in September 2026. Because some capsules hold 250mg and others 500mg, the last price column compares cost for the same 500mg amount. For the wider field, see our comparison of the best TUDCA supplements in Australia.

Add TUDCA 500mg to cart · $59.99

Who each one suits, and who it doesn’t

• Eternal Elixir TUDCA 500mg (our pick). Suits people who want 500mg in one capsule and the lowest cost per 500mg in the table, with 90 capsules to a bottle. It doesn’t suit anyone who wants a lower daily amount than 500mg.
• OHC Longevity TUDCA. Suits buyers who want a certificate of analysis linked from the product page and a 500mg vegan capsule. It costs more per 500mg than ours, and a bottle lasts two months.
• Emrald Labs TUDCA. Suits someone who wants a smaller 250mg daily serve, at the lowest daily cost among the 250mg products here. Taking 500mg means two capsules, which doubles the cost.
• Zombie Labs TUDCA. Suits Nutrition Warehouse shoppers who want a 250mg capsule taken with food. It has the highest cost per 500mg in the table.

Wondering where you can buy it locally? Our guide to whether TUDCA is legal in Australia and where to buy it covers the options.

Our pick: Eternal Elixir TUDCA 500mg

Eternal Elixir makes TUDCA 500mg, and it is our pick for a daily TUDCA supplement in Australia. What is in the bottle:

• 500mg of TUDCA per vegetarian capsule. One capsule is the full daily serve, taken with a meal.
• 90 capsules for $59.99. That is about $0.67 a day. Two bottles save 10%, three save 15% and five save 20%.
• Batch testing. Our product page states that every batch is tested by third-party laboratories for identity, potency, purity and contaminants including heavy metals.
• Sydney dispatch. Orders are dispatched in 1 business day, with a 30-day money-back guarantee, Afterpay and free shipping over $100.

Our Metabolic Wellness Stack ($126.99) already includes a bottle of TUDCA 500mg with berberine and glutathione, so buy one or the other, not both. For timing and amounts, see our TUDCA dosage guide.

Who it suits: healthy adults who want a single daily TUDCA capsule and understand the evidence is still small. Who it doesn’t suit: anyone taking prescribed UDCA or other liver medicines without their doctor’s agreement, and anyone pregnant, breastfeeding or under 18.

Add TUDCA 500mg to cart · $59.99

Frequently asked questions

What is the difference between TUDCA and UDCA?

TUDCA is UDCA with taurine attached. The taurine makes it more water-soluble. UDCA is used as a medicine under a doctor’s care, while TUDCA is sold as a supplement. In the one head-to-head trial, 750mg a day of each gave similar liver blood test results over 24 weeks.

Is TUDCA stronger than UDCA?

Not on the evidence so far. In the only direct comparison, the two gave similar results and similar side-effect rates, although itching became more common on UDCA. No trial has compared them in healthy people.

Can I take TUDCA instead of my prescribed UDCA?

No, not without talking to your doctor. UDCA is prescribed for specific reasons and doses, and the two act in similar ways, so swapping or doubling up should only happen with your doctor’s agreement.

What do bile acids break down?

Bile acids don’t digest food themselves. They act like a detergent, breaking fat into tiny particles called micelles so enzymes can digest it and the body can absorb it. Most bile acids are then reabsorbed and returned to the liver to be used again.

Can you take TUDCA and milk thistle together?

No trial has tested the pair. If you want to try both, add one at a time, and check with your pharmacist if you take prescription medicines. Our TUDCA vs milk thistle comparison covers the evidence for each, and our TUDCA vs NAC comparison looks at another common pairing.

Is TUDCA safe long-term?

The longest trial ran for 24 weeks in patients under medical care, with side-effect rates similar to UDCA. There are no long-term trials in healthy people, so stay on the label serve and review how you feel every few months.

Which TUDCA supplement do we recommend?

Eternal Elixir TUDCA 500mg is our pick, and we make it. It has 500mg in each capsule, 90 capsules for $59.99 (about $0.67 a day, the lowest cost per 500mg in our table) and is dispatched in 1 business day.

Add TUDCA 500mg to cart · $59.99

The bottom line

TUDCA and UDCA are the same bile acid, with and without taurine attached. The taurine makes TUDCA more water-soluble, and in the one head-to-head trial the two performed alike. UDCA is a medicine used under a doctor’s care; TUDCA is the supplement form healthy Australians can buy, with small, short human studies behind it. If you want to try it, Eternal Elixir TUDCA 500mg gives you one 500mg capsule a day for about $0.67. If you take any prescription medicine, especially UDCA, talk to your doctor first.

Related reading

• Best liver support supplements in Australia
• TUDCA at Chemist Warehouse
• Browse the full Eternal Elixir range

Sources

• Chen I, Cassaro S. Physiology, bile acids. StatPearls. 2023. NCBI Bookshelf NBK549765
• Vang S, Longley K, Steer CJ, Low WC. The unexpected uses of urso- and tauroursodeoxycholic acid in the treatment of non-liver diseases. Glob Adv Health Med. 2014;3(3):58-69. PMC4030606
• 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. Medicine (Baltimore). 2016;95(47):e5391. PubMed 27893675
• Kars M, Yang L, Gregor MF, et al. Tauroursodeoxycholic acid may improve liver and muscle but not adipose tissue insulin sensitivity. Diabetes. 2010;59(8):1899-1905. PubMed 20522594
• Walsh LK, Restaino RM, Neuringer M, et al. Administration of tauroursodeoxycholic acid prevents endothelial dysfunction caused by an oral glucose load. Clin Sci (Lond). 2016;130(21):1881-1888. PubMed 27503949
• Product pages for OHC Longevity, Emrald Labs (Elite Supps) and Zombie Labs (Nutrition Warehouse), checked September 2026, linked in the table above.