BELEM, Brazil (Reuters) -"The Amazon brings people health," said Brazilian merchant Edison Rosa, holding out a handful of glistening, dark purple antioxidant-rich acai berries - touted worldwide as a superfood. Belem, a port city in northern Brazil and gateway to the Amazon, is home to the bustling Ver-o-Peso market where merchants come to sell fish, herbs, nuts, berries and other fruit harvested from the world's largest rainforest. In the same city, heads of state from eight nations that share the sprawling rainforest are meeting this week to discuss how to develop the Amazon region in a sustainable way.