Stevia has been on my mind the past week. A friend of mine from Washington asked me about it. The Maestro's Cello Teacher, who is Celiac, also can't eat sugar. Then the Karina, the Gluten-Free Godess, did a run down of sugar alternatives.
The figure ab0ve is a list of the so-called steviosides, a collection of very sweet natural products isolated from the leaves of the stevia tree. They are purportedly 100 times sweeter than sucrose, which is table sugar. If you can make out the structure above, (I know that it's a little small) you can see that glucose (glc) and Rhamose (rham) is linked to a steroid-like carbon skeleton, which is called steviol. It is essentially a natural example of the same principle that gave us olestra (which is totally synthetic). If you stick some sugars onto some large frame, it still tastes sweet to the tongue, but it isn't metabolized.
Scientific Literature I have looked at indicates that it is generally excreted completely unmetabolized. Being unmetabolized, it purportedly has no effect on blood sugar, nor any effect on candida. There is some indication than it has a mild lowering effect on blood pressure, and also some signs that it is beneficial for diabetics. In a test-tube, intestinal flora have been able to cleave the sugars off the steroid-like framework. This framework, steviol, has been shown to be a carcinogen. No studies have shown that this cleavage occurs in the body. That is to say that studies have shown that the cleavage is not observed, not that the studies haven't been done. Granted, you can find haters that will argue that stevia is going to kill you, but that doesn't appear to be supported by the review I read.
How does it bake? Well, I haven't tried it in any baking yet. Reports are that it is stable past 200 Celcius, which not all artificial sweeteners are. Sweet, and stable. Because it IS so sweet, you have to reduce the amount you use considerably. Depending on what form you buy it in, the conversion will change. I found a good conversion table . I come from a Herbally goodness type background, and I can say that the liquid extracts DO taste like licorice when I brushed by teeth with it as a kid. The purer steviosides taste less that way. I'm looking at getting some to try out this week.