As people these days gets more and more diet conscious, this makes good business for manufacturers of dietary food supplements even there's solid facts and studies to prove their effectiveness. One of them is Acai berry, a fruit of a palm specie and now marketed to be a great anti-oxidant and could aid weight loss, cleanse colons. So far, there has been no scientific evidence that acai berries could affect weight loss.
More about Acai berries on the link below.
Link: Acai Berry; Medicines