"If you are drinking modest amounts of green tea you're very safe," says Prof Herbert Bonkovsky, director of liver services at Wake Forest University School of Medicine in North Carolina, who has been tracking injuries linked to green tea supplements for nearly 20 years. "The greater risk comes in people who are taking these more concentrated extracts."
For green tea infusions, EFSA’s experts concluded that there is generally no indication of liver damage even after high consumption, and that the few cases of liver damage reported in humans are likely due to rare and unpredictable reactions. Experts therefore considered catechins from green tea infusions brewed with hot water, and instant and ready-to-drink green tea beverages with similar catechin content, as generally safe.For food supplements, EFSA’s experts concluded – on the basis of human studies conducted with volunteers under medical supervision – that doses of EGCG at 800 mg/day may be associated with initial signs of liver damage. While there was no indication of liver injury for doses below 800 mg/day from green tea supplements, experts were unable to identify a safe dose based on available data.
Results of this review, although not conclusive, suggest that liver-related adverse events after intake of green tea extracts are expected to be rare.
Unfortunately, green tea extract pills are not without risk. There have been about a dozen case reports of liver damage associated with their use. Until there’s more solid evidence of benefit, I’d stick with just drinking the tea. Green or black? A recent study that randomized about a hundred men with prostate cancer to consume six cups a day of green tea or black tea found a significant drop in PSA levels and NF-kB in the green tea group, but not in either the black tea or control groups