Choosing a stevia sweetener brand can make a big difference as to what is actually in it and how it was processed. The best way to get stevia is to use it in it's natural form (dried leaves). However, that is not terribly practical for most people and how they wish to use it. There are three ingredients that stevia manufacturers add that you may want to avoid.
There are a few brands that start with non GMO stevia leaves and then use cold water to extract the stevia. Examples of such brands are NuNaturals and Sweetleaf. If you really want to go natural you can always get the dried stevia leaves and put them in tea strainers to enjoy the sweetness in your beverages.
Stevia is generally safe for most people and that is why it has become such a popular natural sweetener. A benefit for most people is that it lowers blood pressure so for people that have high blood pressure this can be a great asset. However, for those with already low blood pressure this may cause problems in lowering it further. Signs of this include dizziness, fainting, head rushes and poor circulation.
Stevia can also cause allergies for those who are allergic to plants in the Asteraceae or Compositae family such as chrysanthemums, ragweed, marigolds, daisies and others. Allergic reactions can typically be seen in skin rashes and headaches.
Stevia also lowers blood sugar levels which can be a positive thing for health in some people, while in others it may interfere with blood sugar control.
The stevia soda that we found to taste fantastic is by: