From the description I'm willing to bet its polyphenols and some of their customers are sensitive - feed me two pots of green tea and I'll projectile vomit.
I wouldn't be surprised if the fact that it's a powder contributes to this. I've vomited from strong green tea on an empty stomach before, but never from green tea with food. Solid food works as a sustained release mechanism for the nutrients/phytochemicals. A sudden burst of polyphenols won't necessarily have the same effect as the same dose spread over time.
