I was surprised to learn that green tea in high concentrations can be a health risk.
A 16-year-old girl developed acute hepatitis about three months after adding Chinese green tea to her daily diet, states a report in BMJ Case Reports. At first, the girl told the doctors that she wasn’t taking any over-the-counter medicine that could have caused the problem.
However, despite signs of liver damage, the doctors couldn’t find any other sources, such as a viral, autoimmune or metabolic problem. That’s when more specific questioning revealed the girl had ordered Chinese green tea online.
According to Live Science, the girl didn’t know all of the product’s ingredients due to Chinese labeling. To further confirm the doctors’ suspicions, the girl quickly recovered from her hepatitis once she stopped consuming the green tea.
There's more at the link.
It seems that the highly concentrated supplements she was drinking, added to a highly concentrated form of green tea, caused the problem. Green tea in concentrated form can cause a reaction in the liver. In this case, that led to hepatitis - fortunately not the permanent variety!
I drink green tea now and again, although I prefer black; and I tend to make it pretty strong, because that's how I like all my tea, regardless of what type it is. I'll have to re-think that. Those of my readers who do likewise might wish to do the same.