Although one group of studies, perform 1985 through 1987, found one ofthe metabolises of steviosides, called Steviol, to be mutagenic towards a particular strain of Salmonella bacteria, there is serious doubt as to whether this study is applicable to human metabolism of Stevia. In fact, the methodology used to measure the mutagenicity in this test was flawed according to a follow-up piece of research which also seriously questioned the validity of the results. For myself, I intend to use the product with both confidence in nature and respect for the healthy moderation and balance which nature teaches us. Refined sugar is virtually devoid of nutritional benefits and, at best, represents empty calories in the diet. At worst, it has been implicated in numerous degenerative diseases.
Stevia is much sweeter than sugar and has none of sugar's unhealthy drawbacks.
My experience is that the herbal powder is very sweet while the refined extract is incredibly sweet and needs to be diluted to be properly used. Both products have a slight bitter aftertaste, also characteristic of licorice. I do not believe that humans should consume anything artificial in their diets. And industrial usage in Japan proves that this substitution is both practical and economical. And the refined Stevia extracts are considered to be non-caloric.