Green Tea May Cause Liver Damage In Some People: Who Is At Risk?

The risk of liver toxicity is only associated with long-term use of high-dose green tea extract, and the culprit is a catechin called epigallocatechin gallate (EGCG).

Green tea is known to offer numerous health benefits, but it can do more harm than good to some people. A new study has cautioned that an antioxidant found predominantly in green tea may cause liver damage in some people with certain genetic variations.

Studies have shown that drinking green tea helps in weight loss, better digestion, blood sugar control, and reducing bad cholesterol and blood clotting. Long-term use of high-dose green tea extract is also linked to better protection against cancer, cardiovascular disease, obesity and type 2 diabetes. However, the new study conducted by Rutgers University and published in The Journal of Dietary Supplements said that it may also harm liver in a small minority of the population. Are you at risk? Read on to find out.

Who should avoid taking high-dose green tea extract?

The Rutgers research team found two genetic variants that can predict who will suffer liver damage following long-term use of high-dose green tea extract. In the study that included more than 1,000 postmenopausal women, those with these genetic variations were more likely to show signs of liver stress after consuming high dose of epigallocatechin gallate (EGCG), a catechin found in green tea, for a year (843 milligrams 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 of this genotype controls the synthesis of an enzyme that breaks EGCG down.

Early signs of liver damage were somewhat more common in women with a variation in the COMT genotype and strongly predicted by a variation in the UGT1A4 genotype. Nine months after consuming the green tea supplement, the enzyme that indicates liver stress went up to nearly 80 per cent in women with the high-risk UGT1A4 genotype, as against 30 per cent in those with low-risk genotypes saw the same enzyme.

Liver toxicity not associated with drinking green tea

However, the risk of liver toxicity is only associated with high levels of green tea supplements and not with drinking green tea or even taking lower doses of green tea extract, noted Hamed Samavat, assistant professor of nutrition sciences at the Rutgers School of Health Professions and senior author of the study.

He added that they have just taken a step forward towards predicting who can safely take high-dose green tea extract and enjoy any health benefits it can offer.