Green Tea Extract-EGCG-Liver Toxicity

I pay an annual fee to belong to Consumer Lab where some products are tests.  I just received this email that I thought I'd share:
"A large, government-funded study recently found that pills of green tea extract can be safe for many people, but some may experience adverse reactions, including elevated liver enzymes."

"Several U.S. government agencies sponsored a study of the safety of green tea extract given to over 1,000 postmenopausal women at risk for breast cancer. Twice a day for a year, women in the study took 2 capsules with both morning and evening meals, providing a total of 1,315 mg of catechins, of which 843 mg was EGCG(equivalent to about 4 cups of green tea), or a placebo. There was no statistically significant difference in the overall incidence of adverse events between the two groups, but women in the extract group were more likely to experience nausea and skin rashes/allergies and less likely to report diarrhea. In addition, 6.7% of the extract group, but only 0.7% of placebo group, experienced elevations in liver enzymes — a sign of liver injury – and these elevations tended to be greater in the extract group. Enzyme levels returned to normal with discontinuation of the extract in all but one person. The researchers noted that "Though green tea has typically been associated with antioxidant effects, recent evidence has demonstrated a strong pro-oxidant effect of green tea catechins (especially EGCG) that can cause hepatotoxicity when administered in high doses." (Dostal, Food Chem Tox 2015.

The American College of Gastroenterology's clinical guideline for diagnosing and treating drug-induced liver injury, published in 2014, lists green tea extract as one of the most common dietary supplements linked to liver injury and stresses the importance of patients experiencing symptoms of liver dysfunction to inform their doctors of any supplements they may be taking (see the LiverTox Database to search for medications and supplements that may cause liver injury). One of the authors of the guidelines noted that levels of catechins can be over 700 mg in some green tea extract pills and, "This can be particularly dangerous when the pills are taken multiple times a day."

In light of potential liver toxicity, a USP expert committee voted in June 2007 to require the following cautionary statement to appear on the labels for green tea extracts: Caution: Must take with a meal. In rare cases extracts from green tea have been reported to adversely affect the liver. Discontinue use and consult a healthcare practitioner if you have a liver disorder or develop symptoms of liver trouble, such as abdominal pain, dark urine, or jaundice. However, approval of the label requirement was deferred and, in April 2009, the USP announced that the proposed requirement was cancelled. According to a USP spokesperson contacted by ConsumerLab.com, monitoring of adverse event databases from June 2007 through February 2009 showed no additional reports of liver toxicity, but the USP continues to monitor the safety of green tea. However, it may be wise to follow the original proposed guidance to take green tea extract with a meal, as this was given some support from tests on dogs which found that high doses of green tea extract induced lethal toxicity when given without food, but showed no significant toxicity when given with food (Wu, Int J Toxicology 2011.

Green tea contains a small amount of vitamin K, which directly counteracts Coumadin's blood-thinning action; however, enormous quantities of green tea would be necessary to provide a significant amount of vitamin K."