Oprah has been a leading voice in the exponential growth in sales of acai (pronounced ah-sigh-ee) products -- a fruit found in the Brazilian jungles heralded for its antioxidant powers. But now she's under attack for her endorsement from humanitarian types, who say the exploitation of the acai is leaving jungle dwellers starved for one of their favored sources of nutrients.

Soaring yuppie demand for the fruit -- sales doubled to $104 million in 2008 -- has driven prices out of reach for low-income indigenous people.

It seems like much ado about nothing: If acai is being made unaffordable by $104 million in US-driven sales, then it should be easy enough to funnel a chunk of that money back into the communities to raise the standard of living: The emergence of a valuable cash crop should help the people, not hurt them. The fact is that that rarely happens, but perhaps Oprah can use her platform to make sure that the benefits of Acai's popularity accrues at least partly to the poor locals.But long-term, it's probably not going to be a major driver of anything. Its explosive sales growth aside, acai has all the hallmarks of a fad food: Its sales growth is being driven by multi-level marketing hype machines like MonaVie and unrealistic claims and promises have abounded. And what about the antioxidant power? Gourmet reported that "an experiment last year at UCLA revealed that the berry is actually lower in antioxidant potency than many other sources, including red wine and pomegranate, grape, and blueberry juices."

Acai products -- especially the ones sold through multi-level marketing -- are outrageously expensive and don't appear to be spectacular enough to justify the cost. I predict that acai flames out before it has any long-term impact on the Brazilian economy.