Apparently it is some patent.

I also think that you should cross post this in the farm life forum however, I'm sure they would love this information.

It is also claimed that Stevia should work against osteoporosis because of patents taken out on it, although the only one described has to do with eggshells. brendan has pointed out that supposedly lower eggshell breakage does not mean that Stevia will prevent osteoporosis in humans. Something else to consider is whether, if in fact using lots of Stevia makes bones denser, will this translate to better health? There's a controversial anti-osteoporosis drug, Fosamax, that works by making bones denser. Unfortunately there's evidence that at least in a small number of patients, denser bone in the jaw doesn't always get enough blood flow and serious necrosis of the jaw has been reported. Maybe we should wait for clinical studies on Stevia's safety as an osteoporosis treatment, before gulping down large quantities of the stuff to protect our bones?

Sarah the Nutritionist's website is just a bit out of date, since the FDA has approved Stevia as a sweetener. Maybe now she'll tone down some of her conspiracy-mongering (check out the nonsense about Codex Alimentarius and Aspartame Is A Poison OMG!).

Another thought - we often hear from alt med advocates that herbs and other "natural" substances are not commercially developed because they can't be patented. If Sarah the Nutritionist is to be believed, a bunch of patents have been taken out on Stevia, an herb. How could this have happened? :)