A recent study suggests that although long-term consumption of large amounts of green tea may offer some protection against cancer, cardiovascular disease, obesity and type 2 diabetes, it may cause liver damage in a small group of people.
Who is at risk? Research from RutgersPublished in Journal of Food SupplementsIt gives the first strong clue: two genetic variants that predict certain risks.
“Learning to predict liver damage could be very important because there is increasing evidence that high doses of green tea extract have significant health benefits for people who take them,” said Hamed Samavat, senior author of the study and assistant professor. in Nutritional Science at Rutgers School of Health Professions.
Using data from the Minnesota Green Tea Trial, a large study of green tea’s effects on breast cancer, the research team found that people with certain genetic variants were more likely to have symptoms of liver damage after one year of consuming 843 milligrams a day. The main antioxidant in green tea is a catechin called epigallocatechin gallate (EGG).
Researchers led by then-doctoral student and now graduate student Laura Acosta chose two genetic variants that each control the synthesis of an enzyme that breaks down EGCG. They chose the Minnesota Green Tea Trial because it was a large, well-designed study of a specific population. The year-long, placebo-controlled trial involved more than 1,000 women and collected data at 3, 6, 9 and 12 months.
An analysis by the researchers showed that early signs of liver damage were more common in women with a variant in the catechol-O-methyltransferase (COMT) genotype and a variant in uridine 5′-diphospho-glucuronosyltransferase 1A4 (uridine 5′-diphospho-glucuronosyltransferase 1A4). they are. UGT1A4) genotype.
On average, participants with the high-risk UGT1A4 genotype increased their liver stress enzyme by nearly 80 percent after nine months of drinking green tea, while those with the low-risk genotypes had the same enzyme rise by 30 percent.
We are still a long way from being able to predict who can safely consume high doses of green tea, said Samavat, who noted that the risk of liver toxicity is only associated with high doses of green tea supplements, not green tea consumption. Take a small amount of tea or green tea. “Differences in this one genotype do not fully explain the differences in liver enzyme changes between study participants. The full explanation likely involves many different genetic variants and possibly many non-genetic factors.”
Samavat continued, “We still think we’ve identified an important piece of the puzzle and taken steps to predict who will safely enjoy any health benefits that large amounts of green tea may produce.”
Reference: “Hepatotoxicity of High Dose Green Tea Extract: The Catechol-O-Methyltransferase and Uridine 5′-Diphospho-glucuronosyltransferase 1A4 Genotypes” by Laura Acosta, Laura Byham-Gray, Mindy Kurzer, and Hamed Samavat, 30 Sept. 2022; Journal of Food Supplements.