Green tea has many health benefits but can also be harmful to some people. New research warns that an antioxidant in green tea can cause liver damage to some people who have certain genetic variations.
Drinking green tea has been shown to help with weight loss, digestion, blood sugar regulation, and reduce bad cholesterol and blood-clotting. Green tea extract in high doses is linked to a better protection against cancer and cardiovascular disease. It also helps with obesity, type 2 diabetes, and type 2 diabetics. The new study published by The Journal of Dietary Supplements and conducted at Rutgers University found that it could also cause liver damage in a minority of people. Are you at Risk? Find out .
Who is advised to avoid high dose green tea extracts?
The Rutgers team of researchers found two genetic variations that could predict which individuals will experience liver damage after long-term consumption of high-dose extract green tea. The study included over 1,000 postmenopausal woman. Those with these genetic variants were more likely than others to experience liver stress when they consumed high doses of epigallocatechin galate (EGCG), a green tea catechin, for a whole year (843 mg per day).
According to the investigators, the two genetic variations were detected in the catechol-O-methyltransferase (COMT) genotype and the uridine 5′-diphospho-glucuronosyltransferase 1A4 (UGT1A4) genotype. Each genotype controls a specific enzyme responsible for breaking down EGCG.
Women with variations in the COMT gene were more likely to show early signs of liver damage, while women with variations in the UGT1A4 gene were strongly predicted. Nine months after taking the green tea supplement the enzyme that signals liver stress increased to almost 80 percent in women with a high-risk UGT1A4 genetic variant, compared to 30 percent in those with a low-risk UGT1A4 gene.
Green tea consumption not associated with liver toxicity
Hamed Samavat is an assistant professor of nutrition science at Rutgers School of Health Professions. He was the senior author of the research.
He said that the researchers have taken a big step towards predicting which people can take green tea extract in high doses and reap its health benefits.
