Mark: What intake of this green tea extract would you recommend?

Mark,

I have purchased some Green Tea Extract which reccomends to take one a day but the nutritional information for one capsule is as follows

Green Tea extract 315mg
(camellia sinensis) (aerial)
(standardised to contain 15% polyphenois)

15% doesnt seem very strong from what I've read on Fitness Inventor. (i do drink green tea in day aswell)

Will one be sufficient or should I take more?

Thanks in advance

Adam