Recently I have had several people ask my thoughts about the patented alternative sweetener Truvia (tm).
Truvia is a combination of stevia (Rebiana) leaf which is steeped in an acidic water then dried and ground together with erythritol (a sugar alcohol) and "natural flavors" which are not openly disclosed by the manufacturer, Cargill. The reading I have done indicates the natural flavors are excitotoxic (meaning they promote neuron death - brain damage). The stevia part of truvia is just fine - it is the sugar alcohol I have problems with (as is the case for many immune compromised or gut compromised people) - as sugar alcohol ferments in the colon, causing large amounts of water to be drawn into the lower colon, causing diarrhea, bloating, and general discomfort.
The natural flavors are most likely derived from soy or MSG, although the consumer really does not know (and never will) because this part of the "recipe" is patent protected. Personally I would not consume Truvia. It is owned and patented by Cargill and it's true ingredients are unknown. I have tried pure erythritol and have gotten very sick from it (the two times I have used it!).