New research suggests that green tea extract can cause liver damage in a small subset of the population.

According to a recent study, although taking high-dose green tea extract for an extended period may offer some protection against cancer, cardiovascular disease, obesity, and type 2 diabetes, it may also cause liver damage in a small group of people.

Research from Rutgers, published in The Journal of Dietary Supplements, provides the first solid clue: two genetic variants that predict some of the risk.

“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.

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 EGCG down.

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