Green tea extract may damage the liver in people with certain genetic variations

Long-term use of high-dose green tea extract may provide some protection against cancer, cardiovascular disease, obesity, and type 2 diabetes, but it may also cause liver damage in a small minority of the population.

Who is at risk? Rutgers research, published in The Journal of Dietary Supplementsprovides the first strong clue: two gene variants that predict part of the risk.

“Learning to predict who will suffer liver damage is potentially important because there is growing evidence that high-dose green tea extract may have important health benefits for those who can safely take it,” said Hamed Samavat, the study’s lead author and assistant teacher. of nutritional sciences at the Rutgers School of Health Professions.

Using data from the Minnesota Green Tea Trial, a large study on the effect of green tea on breast cancer, the research team investigated whether people with certain genetic variations were more likely than others to show signs of liver stress after a year of ingesting 843 milligrams per day. of the predominant antioxidant in green tea, a catechin called epigallocatechin gallate (EGCG).

Researchers led by Laura Acosta, then a doctoral student, now a graduate, selected two genetic variations in question because each controls the synthesis of an enzyme that breaks down EGCG. They selected the Minnesota green tea trial because it was a large, well-designed study of a single population. The one-year, placebo-controlled trial included more than 1,000 postmenopausal women and collected data at 3, 6, 9, and 12 months.

An analysis by investigators showed that early signs of liver damage were somewhat more common than normal in women with a variation in the catechol-O-methyltransferase (COMT) genotype and strongly predicted by a variation in uridine 5′-diphospho -glucuronosyltransferase 1A4 (UGT1A4 genotype).

On average, participants with the high-risk UGT1A4 genotype saw the liver stress-indicating enzyme increase by nearly 80 percent after nine months of consuming the green tea supplement, while those with low-risk genotypes saw the same enzyme increased by 30%.

“We are still a long way from being able to predict who can safely take a high dose of green tea extract,” said Samavat, noting that the risk of liver toxicity is only associated with high levels of green tea supplements and not with drinking Green Tea. tea or even take lower doses of green tea extract. “Variations in this genotype do not fully explain the variations in liver enzyme changes among study participants. The full explanation probably includes a number of different genetic variations and probably a number of non-genetic factors.”

“Still,” Samavat continued, “we believe we have identified an important piece of the puzzle and taken a step toward predicting who can safely enjoy the health benefits of high-dose green tea extract.”

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Materials provided by Rutgers University. Originally written by Andrew Smith. Note: Content can be edited for style and length.

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