6 supplements, including green tea, turmeric, linked to liver toxicity

• Herbs have been used for medicinal purposes for thousands of years.
• Herbal supplements have recently become very popular due in part to the social media platform TikTok.
• Researchers at the University of Michigan report that an estimated 15.6 million U.S. adults — or 5% — have taken at least one herbal supplement in the last 30 days that might be damaging to their liver.
• Among the supplements studied are ashwagandha, green tea extract, turmeric, or curcumin.

Although herbs and plants have been used for medicinal purposes for thousands of years, they have recently become very popular thanks in part to posts on the social media platform TikTok where users tout the benefits of taking herbal supplements like ashwagandha, turmeric, and green tea.

While herbal supplements may be considered “natural,” they are not inherently safe and don’t require review or approval by the U.S. FDA before going to market. Additionally, people can experience side effects with herbal supplements and certain herbs can interfere with medications they are currently taking.

Now, a new study from researchers at the University of Michigan reports that an estimated 15.6 million U.S. adults — or 5% — have taken at least one herbal supplement in the last 30 days that might be damaging to their liver, or hepatotoxic.

For this study, researchers analyzed data from more than 9,500 U.S. adults with an average age of 47.5 who took part in the National Health and Nutrition Examination Survey (NHANES) years 2017 to 2020. Medical data on these participants included prescription drug and herbal supplement use.

Scientists focused on study participant use of six herbal supplements considered from past research to be potentially hepatotoxic:

“Potentially hepatotoxic botanical products are the products that contain plant-based ingredients which have been implicated as potential causes of liver damage,” Alisa Likhitsup, MD, MPH, clinical assistant professor in the Department of Internal Medicine in the Division of Gastroenterology and Hepatology at the University of Michigan and lead author of this study explained to Medical News Today.

“How these products cause liver damage is not yet known but it is likely due to metabolism that occurs in the liver after the products were consumed,” she said.

“As a practicing hepatologist, I have seen patients who had liver injury from taking dietary supplements and some were fatal which required emergency liver transplant. Data from Drug Induced Liver Injury Network reported the rates of liver injury due to botanical products has been on the rise from 7% in 2004-2005 to 20% in 2013-2014. Therefore, I had (an) interest to analyze the prevalence and see how many Americans were consuming these products,” Likhitsup continued.

At the study’s conclusion, Likhitsup and her team found that about 58% of all participants reported using an herbal or dietary supplement at least once within the 30-day period.

About 5% of participants said they had taken at least one of the six potentially hepatotoxic botanicals in the past 30 days. When applied to the whole U.S. population, this percentage translates to about 15.6 million adults.

“We hope our results will increase awareness among patients and providers about these potentially liver toxic ingredients being consumed regularly among Americans and the dietary supplement products available in the market are not strictly regulated,” Likhitsup said.

“We still do not have the data about the risks of liver injury when consuming one of these products, so it will be difficult for physicians to provide this information that we do not know. And because the available dietary supplement products are not strictly regulated, each product contains multiple ingredients with more than 50% mislabeled. So, it is difficult to do research on this topic.”
— Alisa Likhitsup, MD, MPH

After reviewing this study, Rosario Ligresti, MD, FASGE, chief of Gastroenterology at Hackensack University Medical Center in New Jersey, told MNT that while hepatotoxic botanical products are plants or plant-derived products, given a lack of regulatory oversight on the manufacturing and the lack of testing on these products, consumers need to know they may be causing their bodies more harm than good by consuming them.

“They are completely unregulated [before going to market] so my reaction is that I am not surprised that they can pose significant health risks, particularly for the liver because they are thought to interfere with the liver’s ability to process and detoxify harmful substances,” Ligresti continued. “This can lead to a buildup of toxins in the liver, which can cause inflammation, cell death, and in some severe cases, liver failure.”

Ligresti said that every physician should be talking with their patients about the risks of these types of products and asking if they are taking any of them.

“Because ‘supplements’ are supposedly made from natural ingredients, people have a false sense of security — they may believe that because the ingredients are ‘natural,’ they must be safe. However, it’s important to remember that natural does not always equal safe. Some natural ingredients can be toxic in high doses or interact with medications.”
— Rosario Ligresti, MD, FASGE

“This needs to be explained to patients along with the fact that the supplement industry is not as heavily regulated as the pharmaceutical industry. This means that companies are not required to prove the safety and effectiveness of their products before they are sold. This can lead to consumers purchasing products that are not well-studied or that may contain harmful ingredients,” he added.

“The results of this study are concerning and confirm what I often observe in practice, on social media, and in the healthcare community,” Richard said. “Unfortunately, for a number of reasons, from influencers to clever marketing, to scare tactics and everything in between the market is ripe with products touted to ‘cure,’ ‘solve an ill,’ or ‘enhance a stated outcome,’ when in reality most of the time it is not that simple.”

“The FDA does provide oversight of supplements but specifically related to the potential danger of supplement ingredients on the market which is vastly different than being vetted and ‘approved by the FDA’ for quality, efficacy, safety, and benefit,” she continued.

“The market is rampant with supplement products that are adulterated, compromised, expired, and in some cases, even dangerous. Many times, individuals are self-diagnosing or reading misleading or incorrect information and may be unaware of what they are purchasing, how it may affect them directly, or understand the possible associated side effects or concerns may be.”
— Monique Richard, MS, RDN, LDN

For readers considering taking an herbal supplement, Richard said to first and foremost work with their healthcare team, including their physician, pharmacist, registered dietitian nutritionist (RDN), or other credentialed herbalist or botanist practitioners, to really understand what botanicals may be best suited for their current condition and goals.

She also advised taking a “food-first approach” instead of herbal supplements, such as adding active ingredients like turmeric or green tea in a culinary form, depending on the person’s specific needs and goals.

“Words of wisdom: Turn to your trusted nutrition and healthcare professionals before purchasing promises in a bottle that could be secretly sabotaging your health, your liver, and wallet,” Richard said.