A new study has found that at high doses, polyphenols, in green tea or other such herbs can result in liver damage, leading to significant health risks. The research has been conducted by researchers at University of Toronto, results of which can be found in the Free Radical Biology and Medicine journal.

Previous studies have demonstrated the anti-oxidant effects of polyphenols in reducing the risk of cancer, heart disease and other degenerative disorders associated with increased production of free radicals. Propagation of such benefits without careful analysis in the media has made green tea a popular choice among health conscious individuals, worldwide.

The researchers injected high and low doses of the experimental compound into mice and found that though at low doses, it counteracted free radical damage; it produced liver toxicity at high concentrations. Low concentration admistered is roughly equivalent to the amount of the polyphenols commonly found in black tea/ green tea packages.

Only a small amount of the ingested polyphenols is being absorbed by the intestine. Data regarding metabolism and absorption of the compound is inadequate. The researchers have therefore highlighted the need for extensive clinical trials involving large number of patients to determine the risk-benefit ratio.

The study does not advice refraining from drinking black/green tea but has urged caution among those who would want to exploit the anti-oxidant effect of through consumption of concentrated forms of the compound, probably in a pill form.