What supplements to be wary of as drug-induced liver injuries rise in the U.S.
It started with nausea and loss of appetite.
Robert Grafton, of Turnersville, New Jersey, tried to convince himself he was just coming down with something one weekend in mid-March. Then came the itching and dark urine. Grafton, a former interventional radiology technologist whose wife is a nurse, recognized the hallmarks of liver failure.
The otherwise healthy 54-year-old had a gut feeling that his herbal and dietary supplements were the culprit.
“I stopped taking everything, thank goodness,” Grafton said. “If I hadn’t known, if I was not in the medical field, I might have thought, ‘Oh, I think I’m getting sick. I need to take some more of these supplements to help me feel better.’”
When his symptoms had only worsened by midweek, Grafton visited his primary care physician. The doctor, he said, suspected hepatitis A, a liver infection that can be caused by consuming food or drink contaminated with the hepatitis A virus. Grafton’s laboratory test results showed otherwise.
“My liver enzymes were super elevated, my bilirubin was really high — all the signs of liver failure,” Grafton said. “I pretty much broke down, my wife as well. I was, at that point, thinking it was liver cancer, pancreatic cancer or something.”
That Friday, less than a week after his symptoms had begun, Grafton was admitted to Thomas Jefferson University Hospital in Philadelphia, where he received a diagnosis.
“It turns out I had something called a drug-induced liver injury, which came from my supplements.”
Rising rates of liver damage
The liver is responsible for more than 500 functions in the human body, including filtering harmful substances from the blood. Some people’s livers metabolize toxins more slowly than others, but too much of certain drugs can overwhelm even the healthiest liver.
When taken in excess, acetaminophen, for example, the active ingredient in Tylenol, is among the most common causes of drug-induced liver injury, also called toxic hepatitis. Pharmaceutical products aren’t solely the cause. Herbal and dietary supplements are causing liver damage with mounting prevalence.
From 1995 through 2020, supplement-related liver failure requiring U.S. patients to be waitlisted for transplants increased eightfold, according to a 2022 study in the journal Liver Transplantation. In addition, a 2017 review in the journal Hepatology found that 20% of liver toxicity cases nationwide are tied to herbal and dietary supplements. Because “multi-ingredient nutritional supplements” caused the majority of those cases, the authors said, it’s hard to pinpoint which component(s) may be to blame.
Whereas dietary supplements typically contain nutrients such as vitamins, minerals and amino acids from a range of sources such as fish oil, herbal supplements are a subset of dietary supplements composed of plant-based ingredients.
Liver damage linked to supplements is rare. How rare is unclear.
What is known is why cases are on the rise: More Americans are taking supplements. As many as 3 in 4 adults 18 and older take them, according to a 2024 survey by the Council for Responsible Nutrition, a trade group representing the dietary supplement and functional food industry. Almost 4 in 5 users said they prefer supplements to prescription or over-the-counter medications.
By comparison, the 2017–2018 National Health and Nutrition Examination Survey showed that 58% of adults 20 and older had used a dietary supplement in the past 30 days.
“I think people assume these things are safe,” said Dr. Dina Halegoua-De Marzio, a Jefferson Health hepatologist who treated Grafton. “The No. 1 reason we see people taking these are for good health or to supplement their health, and so I don’t think that they realize that there is a real risk here.”
Grafton was one such consumer. The father of five became more health-conscious when he hit 50, going to the gym and starting a supplement regimen that included fenugreek, DHEA, ashwagandha, L-carnitine and nitric oxide. He continued that cocktail, with few changes, for years without incident. About a month before he got sick, Grafton added turmeric pills to the mix, with the goal of reducing inflammation.
Then Grafton saw the social media promo he said helped set his health crisis in motion.
Ironically, he bought an advertised turmeric-based liquid supplement in part because it claims to support long-term liver health. Similar products are widely available.
“The whole push with that is that you’re getting a super-high, concentrated dose of turmeric and dandelion root and milk thistle, which I have always known from my medical past is good for liver health,” Grafton said. “It all sounded good … I thought I did enough digging.”
He fell ill within a week of adding the liquid supplement to his routine.
Despite Grafton stopping the turmeric pills the day he started the turmeric drink, Halegoua-De Marzio said, turmeric overload likely caused his liver injury. Not only was the drink ultra-concentrated, the pills contained 2,250 mg of curcumin, a substance that comes from the root of the turmeric plant. The pills also include black pepper extract, which Halegoua-De Marzio warned increases absorption twentyfold.
“When you cook with turmeric, that could be really safe. But some of the supplements now are 2,000 mg plus, which is a very high dose of turmeric,” she said. Coupled with black pepper, “the liver now has to break down that supplement and it can’t. It could make it really sick.”
The supplement spectrum includes everything from powders that claim to promote muscle growth to gummies that promise to reduce stress. When it comes to herbal supplements, natural doesn’t necessarily mean better or safer, Halegoua-De Marzio said.
“That’s what I hear from patients all the time — ‘Oh, I want something natural’ — this fear of prescription medicines being unsafe,” she said, adding that while prescriptions bear their own risks, they’ve gone through rigorous clinical trials.
Supplements aren’t subjected to the same premarket testing.
Among herbal ingredients tied to toxic hepatitis, turmeric is the most commonly consumed in the U.S., according to a study published last year in the journal JAMA Network Open. Following that are green tea extract, ashwagandha, Garcinia cambogia, red yeast rice and black cohosh.
About 15.6 million Americans take supplements containing at least one of these six botanicals, the study found. Most reported doing so on their own, not under a doctor’s advice.
Prescription medications are tightly regulated and therefore more easily quantified; it’s difficult to determine how many people consume supplements whose ingredients can cause liver damage. A goal of the JAMA Network Open research was to capture this magnitude — at least where herbal supplements are concerned — said co-author Dr. Robert Fontana, a professor of internal medicine at the University of Michigan Medical School.
“It’s important for other doctors to know, for the general public to know,” Fontana said. “The denominator of use is going up.”
Fontana and Halegoua-De Marzio are part of the Drug-Induced Liver Injury Network, a research group backed by the National Institute of Diabetes and Digestive and Kidney Diseases, part of the National Institutes of Health. More than 1,800 patients have been enrolled since the program’s 2004 inception, with 19% of cases tied to supplements.
Previous research has estimated that the U.S. sees 44,000 cases of liver damage linked to medications and supplements annually, including 2,700 deaths. The actual incidence is likely higher, Fontana said. Liver failure symptoms can be vague, so some people may be unaware they have the condition. People who sought natural remedies in the form of supplements may be wary of seeing a doctor. Others, Fontana said, may be embarrassed about inadvertently harming themselves; botanical users in his 2024 research were older, wealthier and more educated than nonusers.
“When you’re the patient, you’re like, ‘Why did this happen to me?’” Fontana said. “‘What do you mean, this stuff isn’t safe?’”
FDA doesn’t monitor supplement safety before sale
For Joanne Slavin, a registered dietician and professor in the department of food science and nutrition at the University of Minnesota, consumer education on the risks and rewards of supplements is critical.
“We really only know human data when something goes wrong,” she said.
The Food and Drug Administration maintains a searchable database of recalls, market withdrawals and safety alerts but can’t vet supplements for safety or effectiveness before they hit store shelves. Only once they’re on the market does the agency have the authority to penalize “adulterated or misbranded” products. That’s thanks to the Dietary Supplement Health and Education Act of 1994, which limited the FDA’s reach. The number of supplements on sale today is almost 20 times as many as three decades ago.
Consuming supplements comes with risks, the FDA warns.
“Dietary supplements may contain ingredients that can have strong effects in the body, even if the ingredients are natural or plant-derived,” the agency said in a statement to NBC News. “Adverse events are more likely to occur if consumers take supplements in high doses, take multiple supplements or take supplements instead of or in addition to medications.”
According to the Council for Responsible Nutrition (CRN), dietary supplements can’t make claims concerning the prevention, diagnosis, mitigation or curing of a disease.
“Dietary supplements can’t say they can cure your cold, they can’t say they can prevent your Alzheimer’s or your cancer,” CRN President and CEO Steve Mister said. “If you see (such) a product out there, it is blatantly illegal.”
Dietary supplements have their place
In short, he said, supplements are intended for healthy people who are trying to stay healthy.
While everyone should ideally get all nutrients through a balanced diet, Slavin said, she recognizes that dietary supplements have their place. People who don’t eat red meat, for instance, may need to seek an alternate source of iron.
“A supplement is fine, sure,” she said. “But that’s on the individual basis rather than the public health basis for the whole world.”
Monitoring how many vitamins or mineral supplements are taken daily is straightforward, Slavin said.
The federal Office of Dietary Supplements has established daily upper limits for nutrients, from vitamin A to zinc, which vary by age and sex. Calcium, for example, has an upper limit of 2,000 mg per day for adults 51 and older — including food, drink and supplements.
Herbal supplements have no such boundaries and aren’t as well studied.
“Everything can be toxic at a certain amount,” said Andrea Wong, CRN senior vice president of scientific and regulatory affairs. “It’s really up to the manufacturers and the researchers who are looking at these ingredients to determine what is the beneficial amount … then also look at what would be the amount where you start seeing some evidence of toxicity.”
She said it’s important to let your doctor know about any supplements you’re taking or starting. Some supplements may interfere with prescription medications or each other, or be unsafe for people with certain medical conditions. For example, the FDA advises against taking any combination of aspirin, vitamin E, prescription warfarin or herbal supplement ginkgo biloba — all are blood thinners and may increase risk of stroke or internal bleeding.
According to Fontana, some people are even genetically susceptible to supplement-induced liver damage.
“That means there’s a biological basis as to why they were the one in 1,000, one in 10,000 people who took this and got into trouble,” Fontana said of supplements. “The same thing is true for prescription drugs; we’re finding genetic associations.”
The federal LiverTox database is a free tool highlighting medicines and supplements linked to liver injury.
The liver is usually a forgiving organ, Fontana said.
Grafton’s was. His hospital stay was brief, and he said his blood work had returned to normal within weeks of ceasing supplements. Additional testing revealed no permanent damage to his liver.
He said he has a new lease on life and resumed his health kick — with one notable exception.
“I don’t take any supplements whatsoever.”