Ok.. i read this thing about guava's.. they are a 'rich' source of oxalate, meaning that oxalate ions are supposedly good for us. I read on wikipedia, and i found that oxalate ions cause kidney stones. So, right here i'm just guessing that it's the 'quantity' that matters. So, my question is that.. basically.. how much of oxalate is harmful to the human body. And a quantity below that.. which is good for us, how is it good for us.. thanks.