We all know that tea is meant to be good for us. We have blogged about it a few times ourselves. But too much of a good thing can make it bad and that seems to be true for green tea too.
Reported in the Journal of Functional Foods, researchers fed fruit fly larvae (Drosophila melanogaster) green tea polyphenol and then measured, for example, the effect on size and growth, lifespan and stress responses. In a previous publication they found green tea consumption increased the lifespan of male flies and wanted to expand on this study.
This time, they found that excessive amounts of green tea polyphenols caused the larvae to grow slower, and fewer made it to adulthood. Female flies had reduced fertility. This was not seen in males but they did have smaller testicles.
The researchers say that as humans share many biological pathways with Drosophila melanogaster these results suggest that excess green tea could also be detrimental to us too. They do finish with the fact though, that it is not yet known how bioavailable polypenols are in mammals and flies and therefore it is difficult to draw direct conclusions on how this affects us.
I would stick with the message that this is caused by excess amounts, and that at normal consumption of green tea has been shown to have health benefits.