Some info I found:
Stevia is an herb native to South America The Guarani Indians of South America call this herb "Ka-Hee". The natives of South America have enjoyed the benefits of stevia for centuries. Now, this remarkable herb is available in the United States as a dietary supplement. Stevita Stevia is Completely Gluten-Free and Safe For Diabetics.
The secret to stevia's special quality is found in the complex compound Stevioside.The higher the percentage of steviosides,the more effective the extract.
Anyone trying to avoid sugar, hypoglycemics, diabetics, dieters, over-active children, and anyone concerned about the over-use of sugar in today's diets and prepared foods!
Totally Safe And Free Of Chemicals! -You can have peace of mind with stevia by Stevita - the only supplier to grow their own plants,cultivate, harvest and use a 'patented' water and filtration method to extract the steviasides from the leaves. You can be certain of consistent high quality premium products. No Bitter aftertaste.
Stevita uses no bleaching agents, alcohol or chemicals. This is demonstrated by the creamy white color of their stevia powder instead of having a bleached out paper white appearance. Stevita stevia is the only one with 96% steviosides,the active component of the leaf. This means we have removed 96% of the bitter by-products of the leaf. The higher the percentage, the better the flavor and the strength.