Stevia

These are a couple of interesting articles about the history of the sweetener stevia, and how the natural (pure leaf) form is (still?) only approved to be sold in the U.S. as a "dietary (or herbal) supplement" and not as a sweetener, whereas one of the extracts is allowed to be marketed as a sweetener.

http://nutritionwonderland.com/2009/02/stevia-controversy/

http://nutritionwonderland.com/2009/02/science-truvia-and-purevia-rebiana/