Here's one of the studies. It looks formidable but its conclusions are simple. In translation: MonaVie contains antioxidants. The antioxidants in MonaVie act like antioxidants in the test tube and in the body, and they work better than potato starch, which has no antioxidants. Why am I not surprised? This is a study sponsored by the manufacturer.
You can read about this study and the rest of fuss over this juice in the March 12 New York Times. It's in the Style Section (where else?). The bottom line: all juices have antioxidants and most are a lot cheaper than MonaVie.
As for weight-loss claims: This month's Nutrition Action Healthletter explains how to analyze Internet advertising, using Açaí as an example of truth-bending.




There's a great article on Acai posted on Gourmet.com. The locals of the Amazon, where Acai is harvested "certainly don’t see it as a means of losing weight—quite the opposite... they’ll tell it to you straight: “Açaí makes you fat." Hmm, interesting.