Green tea will only help keep you healthy if it is taken in moderation, warn boffins.
The drink is credited with keeping cancer and heart disease at bay, but too many cuppas a day could cause liver and kidney damage, say experts, who conducted a review of studies into the toxicity of polyphenols present in green tea.
Lead author Chung Yang of Rutgers, the State University of New Jersey, insists that though up to 10 small cups of green tea a day won’t do you any harm, it is people who take supplements, which can contain up to 50 times as much polyphenol as a single cup of tea, that are at risk.
"People shouldn't be too alarmed by this, but those taking supplements may experience problems," the New Scientist quoted Professor Yang, as saying.
As a part of his review, Prof Yang's looked at experiments in which rats and dogs died from liver poisoning after being given very large doses of polyphenols.
He also found that there were reported cases of people with liver toxicity after overdosing on green-tea-based supplements.
Though the symptoms of liver toxicity stopped around the same time as when these people stopped taking the pills, they returned once the subjects started taking the supplement pills again.