Health - Green tea can be harmful in large quantities

Discussion in 'Ethnobotanicals' started by enquirewithin, May 7, 2007.

  1. enquirewithin

    enquirewithin Gold Member

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    Dec 11, 2004
    from bermuda
    "People shouldn't be too alarmed by this, but those taking supplements may experience problems," says lead author Chung Yang of Rutgers, the State University of New Jersey.
    He stresses that up to 10 small cups of green tea a day is fine. Problems are likely in people who take supplements, which can contain up to 50 times as much polyphenol as a single cup of tea.
    Yang's review cites experiments in which rodents and dogs died from liver poisoning when given very large doses of polyphenols. He also reports cases of people with liver toxicity after overdosing on green-tea-based supplements. Their symptoms disappeared when they stopped taking the pills, only to return when they started taking them again (Chemical Research in Toxicology, vol 20, p 583).
    Last edited by a moderator: Sep 9, 2017
  2. NeuroMD

    NeuroMD Newbie

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    Jun 1, 2008
    53 y/o
    Important notes:

    ""The authors of these reports, however, could not conclusively rule out the involvement of potentially hepatotoxic pharmaceutical agents such as acetaminophen or other dietary supplements.""

    The above was a few case reports and not a toxicity study.

    ""Oral administration (po) of Teavigo (a green tea polyphenol preparation containing 90% EGCG) or Polyphenon E for 13 or nine weeks, respectively, to Beagle dogs resulted in dose-dependent toxicity and death (19). ""

    The study was designed to find out at what dose it becomes toxic, what was left out of his report was the conclusion of the actual study.

    ""An oral dose delivering 2000 mg EGCG preparation/kg was lethal to rats; whereas, a dose of 200 mg EGCG/kg induced no toxicity. The dietary administration of EGCG preparation to rats for 13 weeks was not toxic at doses up to 500 mg/kg/day. Similarly, no adverse effects were noted when 500 mg EGCG preparation/kg/day was administered to pre-fed dogs in divided doses. This dose caused morbidity when administered to fasted dogs as a single bolus dose, although this model was considered an unrealistic comparison to the human condition. From these studies a no-observed adverse effect level of 500 mg EGCG preparation/kg/day was established.""