Green tea supplements and liver injury in people
What it found
Among people with liver damage linked to supplements, green tea was the most common single cause.
Nearly three quarters of those patients carried a specific gene variant found in only about one in ten people overall.
What they found
Studies in people
Mostly pills, not drinks
In 32 out of 40 cases, the green tea was part of a multi-ingredient pill. Only eight people were taking green tea extract alone. Most were taking it for weight loss.
A specific gene variant
The gene variant HLA-B*35:01 was found in 72% of the green tea liver injury cases. It appeared in only 15% of people hurt by other supplements and 11% of the general population.
Symptoms and severity
Symptoms usually started about two to three months after taking the product. Most patients turned yellow from jaundice. Three people needed a liver transplant, but no one died.
Repeat exposure caused faster harm
Three people got liver damage again after taking green tea products a second time. The second time, symptoms appeared much faster, in about two to three weeks instead of months.
Other findings
Catechins in the products
Lab tests on 16 of the products showed that all but one contained catechins, the active plant compounds in green tea. Amounts per serving ranged from 6.6 to 384 mg.
What the authors conclude
- They conclude that liver damage from green tea supplements is closely tied to a specific gene variant, suggesting the immune system is involved.
- Their findings show this reaction is unpredictable and depends on a person's genetics rather than just the amount taken.
- The authors suggest testing for this gene variant could help doctors figure out if green tea caused a patient's liver injury.
How it was done
Herbal supplements are increasingly linked to sudden liver damage, and green tea is often an ingredient in those products. Scientists wanted to understand who gets sick and why, since drinking brewed green tea has not been tied to these problems.
Researchers looked at 1,414 people in a U.S. database who had liver damage from drugs or supplements. They identified 40 cases linked to green tea, mostly from pills rather than drinks. They checked the patients' symptoms, tested their genes, and analyzed the products they took.
What it can’t tell you
- This study tracked people who already had liver damage, so it cannot show how often green tea pills cause problems in everyone who takes them.
- Because most cases involved multi-ingredient pills, scientists do not yet know if green tea extract alone would have caused the same harm in every case.
- Having the gene variant raises the chance of liver injury, but not everyone with the variant who takes these pills will get sick.
Who paid
- Funding
- Funded by NIDDK NIH HHS; NIGMS NIH HHS (from the PubMed record).
- Authors work at
- National Institute of Diabetes and Digestive and Kidney Diseases, MD; National Cancer Institute, MD; Wake Forest University School of Medicine, NC
The paper
- Title
- HLA-B*35:01 and Green Tea-Induced Liver Injury
- Type
- Study
- Evidence
- Studies in people
- Summarised from
- Full text
- Cite
- Hoofnagle JH, Bonkovsky HL, Phillips EJ, et al (2021). HLA-B*35:01 and Green Tea-Induced Liver Injury. Hepatology (Baltimore, Md.). doi:10.1002/hep.31538Free full textPubMed 32892374DOI
Summary written 1 Oct 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error