Turmeric and black pepper supplements linked to liver injury in some people

• The spice turmeric is a popular food supplement due to a molecule it contains called curcumin, which acts as a strong antioxidant.
• it is also thought that it could be used to treat or prevent inflammatory conditions.
• Turmeric’s use has grown in popularity in the past decade or two, with people using it in the hopes that it improves symptoms of different conditions or prevents cancer.
• Doctors have raised concerns about its safety after discovering a small group of patients have experienced liver injury after taking turmeric supplements.

Turmeric supplements have been linked to a number of cases of liver injury, most recently in a United States-based study.

Previous research from Italy and published case studies have linked turmeric supplementation, or supplementation with its active compound curcumin, to liver injury. This latest research shows rates of liver injury linked to turmeric could be increasing.

The latest study, published inThe American Journal of Medicine in 2023, looked at the turmeric-associated liver injury cases recorded in the US by the US Drug-Induced Liver Injury Network (DILIN) between 2004 and 2022.

The researchers discovered 10 cases of turmeric-associated liver injury, all after 2011 and six of which occurred since 2017. Five patients were hospitalized, and one patient died of acute liver failure. The authors identified a risk associated with taking turmeric and black pepper supplements together.

Jay Hoofnagle, MD,Trusted Source one of the study’s authors and director of the Liver Disease Research Branch in the NIDDK Division of Digestive Diseases and Nutrition who oversees the DILIN, told Medical News Today in an interview:

“So the question we’re always asked is, how come now, suddenly you’re seeing this? And that’s a very important question. Why? One reason is that it’s being used by millions of people now.”

“But the other reason is turmeric is a spice, right? It is not absorbed. You don’t absorb pepper. Your body doesn’t absorb it. You don’t absorb curry, the spice turmeric. Okay, so how could this possibly cause liver disease if it’s not absorbed? Well, the answer, we think, is that these modern products of turmeric have been altered so that they are absorbed,” he said.

Seven of the 10 individuals identified as having liver injury following turmeric supplementation carried a specific human leukocyte antigen (HLA) allele, known as HLA-B*35:01, despite this normally existing in the population at a frequency of about 6-7%. HLA alleles are genes that code proteins that help the immune system recognize cells as either part of the body or as foreign objects, meaning they play a role in immunity or autoimmunity.

Hoofnagle said they could not say with certainty that all of the cases they discovered were due to turmeric, as many of the people they identified with liver injury were taking other drugs at the time. There did appear to be a particular risk for people with the HLA allele HLA-B*35:01, which needs further investigation.

“So, of our 10 cases, we could be wrong about several of them. So, it may be that this allele is absolutely necessary. We don’t know that when we look at the cases that had the allele and compare it to the three that didn’t, the cases with the allele had this classic, look, you see, whereas the ones that didn’t have the allele, they were a little bit different,” Hoofnagle said.

He and other authors are currently looking at conducting further research to better understand this allele and the mechanisms underpinning the heightened risk of liver injury they had observed.

One of the reasons why liver injury occurs in certain individuals could be that curcumin is a phenolic compound, which makes it a bioactive compound in the human body.

Previously, research has shown that people carrying this genetic variant were more likely to experience liver injury after using Polygonum multiflorumTrusted Source, an herb native to China and used in traditional Chinese medicine.

Hoofnagle explained that the use of green tea supplements, mostly in the form of weight loss supplements, had also been linked to liver injury.

“These other herbals that have been implicated also have phenols. So it’s beginning to kind of come together that something about phenols affects [carriers of] B*35:01 and makes it react in the liver,” he said.

Kristin Kirkpatrick, MS, registered dietician and a dietician at Cleveland Clinic told Medical News Today that it was important to consider the bigger picture when analyzing this data, and consider the other factors that can influence liver health:

“This study examined not only turmeric in a supplemental form but also the addition of piperine, which appeared to enhance bioavailability. The liver is the body’s TSA agent. You can’t move forward in the body without first being screened by this gatekeeper. Supplements make their first stop there, and therefore, the liver takes the brunt of the energy the body takes to break down, detoxify, and allow in or remove.”
— Kristin Kirkpatrick, MS

“In regards to liver injury, it’s estimated that potentially 1 in 3 individuals now have metabolic dysfunction-associated steatotic liver disease (MASLD) and the further along the disease is, the harder for the liver to do its job well. If it can’t detoxify efficiently, it’s more likely to experience injury,” Kirkpatrick said.