Washington [US], December 4
Long-term consumption of high-dose green tea extract may provide some protection against cancer, cardiovascular disease, obesity, and type 2 diabetes, according to one study, but it may also cause liver damage in a small percentage of people.
Who is in danger? The first concrete hint comes from Rutgers research, published in The Journal of Dietary Supplements: two genetic variations that predict some of the dangers.
“Learning to predict who will suffer liver damage is potentially important because there’s growing evidence that high-dose green tea extract may have significant health benefits for those who can safely take it,” said Hamed Samavat, senior author of the study and an assistant professor of nutrition sciences at the Rutgers School of Health Professions.
Using data from the Minnesota Green Tea Trial, a large study of green tea’s effect on breast cancer, the researchers looked to see if people with certain genetic variations were more likely than others to show signs of liver stress after consuming 843 milligrammes per day of the primary antioxidant in green tea, a catechin called epigallocatechin gallate (EGCG).
Researchers led by Laura Acosta, then a PhD student and currently a graduate student, chose the two genetic polymorphisms in issue because each regulates the manufacturing of an enzyme that breaks down EGCG.
The Minnesota Green Tea Trial was selected because it was a large, well-designed trial of a distinct demographic. The year-long, placebo-controlled experiment included over 1,000 postmenopausal women and gathered data at three, six, nine, and twelve months.
An analysis by researchers showed that early signs of liver damage were somewhat more common than normal in women with one variation in the catechol-O-methyltransferase (COMT) genotype and strongly predicted by a variation in the uridine 5′-diphospho-glucuronosyltransferase 1A4 (UGT1A4) genotype.
