Not necessarily. Whole leaf and crude Stevia extracts are currently not considered GRAS (generally recognized as safe) and have not been approved as food additives.
Only specific manufacturers of the highly refined extracts (Rebaudioside A) have been given GRAS status. These companies and products are listed on FDA's website under "GRAS Notices."
Stevia Extract should only consist of Stevia, broken down into liquid form, and natural flavors. www.steviasmart.com
I don't know if this is the information you are looking for but it might be helpful. There is a cactus plant from Mexico called the blue agave plant. It is related to the lily and is usually found with cactus but it is not a cactus plant. It was considered a sacred plant but it is said that when the Spaniards arrived, they used it to make Tequila. However, manufacturers have found that it is naturally sweet and makes a wonderful replacement for sugar. It is 10% glucose and 90% fructose (a natural form). It does have calories but it is considered a low glycemic index food -- a food that doesn't stimulate insulin production. Hope this helps.
Stevia natural sweetner is very, very sweet you might want to find a recipe that does substitutions. Maybe in a health store.