As high doses of green tea extract supplements for weight loss become more popular, potential liver toxicity becomes a concern, researchers said. Experts in Penn State's College of Agricultural Sciences gave mice high doses of the green tea polyphenol epigallocatechin-3-gallate (EGCG).

The dosage was equivalent to the amount of the polyphenol that is present in some dietary supplements taken by humans.

One group of mice was pre treated with a diet conta8ining a low level of EGCG for two weeks prior to receiving high doses of the polyphenol.

Another group was fed a diet that did not include EGCG prior to receiving the high, supplement-like doses. After three days of high doses, pretreated mice had a 75% reduction in liver toxicity compared to untreated mice.

The research data shows that dietary pretreatment with the green tea poly-%phenol protects mice from %liver toxicity caused by sub8sequent high oral doses of %the same compound, said Josh Lambert, associate professor of food science.

"We believe this study indicates that those who are chronic green tea consumers would be less sensitive to potential liver toxicity from green-tea-based dietary supplements," he said.

"If you are going to take green tea supplements, drinking green tea for several weeks or months ahead of time may reduce your potential side effects," Lambert said.

Tea is rich in catechins, polyphenols that are natural antioxidants. A number of animal studies have shown the preventive effects of green tea polyphenols against obesity.

Lambert pointed out that a recent analysis of 11 human trials with green tea preparations reported a nearly three-pound average body weight loss in intervention groups compared to control groups.

Another recently published research in Food and Chemical Toxicology, has revealed a unique property of the green tea polyphenol EGCG.

"It appears that EGCG can modulate its own bioavailability and that dietary treatment may reduce the toxic potential of acute high oral doses of EGCG," said lead researcher Sarah Forester, assistant professor of chemistry, California State University, Bakersfield, a former Penn State postdoctoral fellow.

"These data may partly explain the observed variation in liver toxicity response to dietary supplements containing green tea," Forester said.

Lambert suggests that people considering green tea supplements should drink green tea instead.

"Drinking green tea rather than taking supplements will allow you to realise the benefits and avoid the risk of liver toxicity," he said.

(TOI)