Oz, who appears on "The Oprah Winfrey Show" as a medical expert, told ABCNews.com earlier this year that he had never officially endorsed acai.
"Acai is a powerful antioxidant," said Oz. "Colorful, dark foods like red wine, pomegranates, concord grapes, blueberries -- they call them brain berries -- are full of nutrients."
As far as those weight loss properties, Oz said, "I'd be surprised if by itself acai could help."
Acai products are distributed through such stores as Whole Foods, Wild Oats and Jamba Juice, as well as many conventional grocery chains and the Web.