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BARCELONA, Spain — Herbal and dietary supplements (HDS) marketed for wellness, weight loss, inflammation, and energy boosting are increasingly being linked to severe liver injury, hepatologists warned here at the European Association for the Study of the Liver (EASL) Congress 2026.

At a session dedicated to HDS-related liver injury, speakers highlighted mounting concerns over concentrated herbal extracts, supplement "stacking," inconsistent manufacturing, adulteration, and weak regulatory oversight against a backdrop of rapidly rising supplement use worldwide.

"The message is that not all natural things are safe," Lily Dara, MD, associate professor of medicine at the University of Southern California (USC), Los Angeles, told Medscape Medical News.

"Patients are often not disclosing what herbal and dietary supplements they're taking, so physicians should actually ask about that, especially when dealing with abnormal liver enzymes," she said. Clinicians should be particularly alert to products containing green tea extract, turmeric/curcumin, ashwagandha, kratom, black cohosh, and bodybuilding or weight-loss formulations.

Rising Cases 'Tip of the Iceberg'

Data from the US Drug-Induced Liver Injury Network (DILIN) suggest that HDS-related liver injury is increasingly recognized and may account for a substantial proportion of severe drug-induced liver injury cases, said Dara.

And the true scale of supplement-related hepatotoxicity may be underestimated, she said. "This is probably the tip of the iceberg. There are likely many more cases that go undiagnosed or missed because we are not asking patients if they are taking herbal and dietary supplements." 

Data from the DILIN show that HDS-related liver injury may have a particular phenotype, said Dara. "In general, herbal dietary supplements seem to have a much higher percentage of patients [~80%] presenting with hepatocellular injury than non-HDS medications such as antibiotics and other pharmaceutical compounds [around 50%]." 

It has also been shown that women may be disproportionately represented among hepatocellular presentations, she added. 

"It's important to understand that some of these injuries are severe," Dara noted. "There are patients who become jaundiced, hospitalized — there are even rare cases of liver failure requiring liver transplantation."

One major issue, she said, is that many consumers fail to recognize supplements as biologically active compounds capable of causing harm. "Patients often do not think of supplements as medicines," Dara said. "They assume that because something is natural, it must be safe."

But "if you take a compound from a plant, purify it, concentrate it, and put it into a capsule, chemically and biologically it may behave much more like a pharmaceutical than a food," she said.

The problem may be compounded by social media marketing and influencer culture, according to session moderator Einar Björnsson, MD, professor of medicine at the University of Iceland, Reykjavik.

"People listen to TikTok and social media influencers more than grey-haired middle-aged doctors," Björnsson told Medscape Medical News. "That is part of the problem," he said, adding that most individuals taking supplements will not experience toxicity, but some patients are genetically susceptible.

"It has been shown that those who have a genetic susceptibility — a certain HLA class — are at risk," he said. "The problem is that nobody knows beforehand who is susceptible."

Green Tea Extract and Turmeric Highlighted

Green tea extract (GTE), commonly used in weight-loss products, emerged as one of the most discussed examples during the session.

Dara stressed that clinicians should distinguish between ordinary dietary consumption and concentrated extracts used in supplements.

"A cup of green tea is safe," she said. "We're talking about concentrated extracts delivering much higher doses."

According to slides presented at the meeting, more than 100 cases of liver injury linked to GTE have been reported. Dara explained that high concentrations of epigallocatechin gallate (EGCG), a catechin found in GTE, may contribute to oxidative stress and liver toxicity. "These polyphenols tend to cause oxidative stress and liver toxicity at high doses," she said.

Injury typically develops within 1 to 6 months of exposure and often presents with a hepatocellular hepatitis-like syndrome accompanied by marked liver enzyme elevations.

Dara also warned about "supplement stacking," in which consumers combine multiple products marketed for similar effects. "Patients stack these polyphenols," she said. "They take Garcinia cambogia, then turmeric, plus green tea, then another compound with multiple ingredients."

And some individuals may still develop hepatotoxicity even at lower doses, she added. "We really do not know what the safe threshold is, and who will get toxicity."

The session also highlighted evidence linking GTE hepatotoxicity with the HLA-B*35:01 allele. Similar associations have been reported with turmeric-related liver injury.

Turmeric supplements were another major focus, with particular concerns around formulations combined with piperine (black pepper extract), which may substantially increase curcumin bioavailability. Liver injuries due to turmeric are usually hepatocellular in pattern and often develop after 1 to 4 months of use, although batch-to-batch variations can affect latency. Some severe cases and deaths have been reported.

Dara emphasized that modern supplements differ markedly from traditional culinary use. 

"If you want to use turmeric, use food-grade turmeric in small amounts as part of your diet," she said. "Humans have been doing that for thousands of years. What's different now is that we're turning these into pharmaceutical products."

Loose Regulation Called Difficult to Justify

Dara and several other speakers questioned whether current regulations adequately reflect the pharmacological activity of many supplements.

There is a lot of consumer demand for HDS, and it is a large industry, although the scientific evidence supporting these products can vary widely. Unlike prescription medications, dietary supplements are regulated differently in the US, and they are generally not required to undergo the same level of large randomized controlled trials in humans for efficacy and safety before reaching the market.

In the US, supplements are regulated under the Dietary Supplement Health and Education Act of 1994 and are classified as foods rather than medicines, said Dara. "Companies do not have to prove effectiveness or safety before selling them."

She also highlighted concerns about adulteration and contamination, with data showing that up to 51% of dietary supplements may contain inaccurate or incomplete ingredient labeling. "In many countries, there's not enough regulatory oversight," she said. "You can have heavy metals, contaminants, or even products adulterated with pharmaceuticals."

Björnsson said the discrepancy between strict pharmaceutical oversight and comparatively loose supplement regulation is becoming increasingly difficult to justify. 

"These compounds are sold like drugs, in bottles with milligrams and marketed claims, but without the same regulation," he said. "There should be more regulation."

Clinicians Urged to Ask Patients Directly

Speakers repeatedly stressed that clinicians evaluating unexplained liver abnormalities should routinely ask about supplement use, including teas, powders, bodybuilding agents, and traditional remedies.

Patients frequently omit supplements from medication histories unless specifically prompted, either because they do not regard them as medicines or because they assume they are harmless.

Dara said clinicians should approach these conversations carefully, particularly in culturally diverse settings where herbal medicines may have longstanding traditional use.

"I try not to dismiss patients' beliefs or traditions," she said. "But I explain the uncertainty and the potential risks."

Ultimately, she advised clinicians to encourage patients to critically assess whether supplements are genuinely necessary and, where possible, to avoid poorly labeled or unverified products purchased online.

"Best-case scenario," Dara said, "patients are making very expensive urine."

Dara reported conducting expert witness work related to hepatotoxicity. She reported no other relevant financial relationships. Björnsson reported no relevant financial relationships.