Think about the amount of green tea (the plant) that you actually consume in a cup of tea. Even if it's loose tea and you've done a sloppy job, perhaps a few granules.
Now imagine popping a couple of capsules packed with the stuff every day. All of a sudden your intake of something has spiked a few hundred times. It could be cinnamon and you'd have health consequences.
Go to a tea shop and order some Dragonwell, and drink it. Then have a bowl of matcha. You will feel the difference, and it can be a rather alarming one.
Edit: Why that's a big distinction: Your body typically flushes water soluble chemicals fairly easily. It has a harder time with the ones that aren't water soluble, so they tend to accumulate over time. So capsule of tea leaves is probably not the same thing as a cup of tea, from a pharmacological perspective, and theres good basis to assume that it has a lot more ability to hurt you. The same goes for pill version of traditional medicinal teas (echinacea, kava kava, etc.)
Funny that you picked that as an example: https://en.wikipedia.org/wiki/Cinnamon#Toxicity
Same thing: tasty, used for ages, but problematic in large quantities.
The seeds contain 1-3% coumarin. In large quantities, it's toxic to the liver and kidneys, and is banned as a food additive in the US.
As others noted, there are a lot of things we consume in normal doses that if you consumed 10-50x as much would likely cause problems for at least some percent of the people who eat them.
Exactly: try drinking 50x as much water as you normally do. You'll probably die of water poisoning. Is water a poison?
And dosage matters.
No it's not. Green Tea is a manmade liquid made from natural leafs. And those leafs are usually not eaten over a longer timeframe.
I've had a friend who worked at a chemical testing lab for a grocery chain who flat out stopped drinking tea - even organic certified - after running the tests for the client. Every single brand tested positive for quantities a trained biochemist wasn't comfortable with.
I can't imagine how bad concentrated extracts are.
>This article is only interesting if you still conflate "green tea" with "natural" and "natural" with "safe".
Green tea _is_ natural. And I conflate "consumed daily by millions of people for thousands of years without incident" with safe. Green tea is not an obscure herb like echinachea or ginko biloba. The idea that putting it in capsules would make it dangerous is not obvious at all. It sounds like magical thinking. So the fact that it is true, and it is in fact dangerous, is actually quite curious to my mind.