A sweetener called stevia

Dear Skeptical,

Your skepticism is warranted, considering the label "all natural" does not have one, standard definition or imply “risk-free.” In order to be approved by the Food and Drug Administration (FDA), sweeteners marketed as “Stevia” may contain only one highly refined component of the stevia rebaudiana plant, called Rebaudioside A. Due to potential health risks, no other components of the stevia plant have been approved by the FDA as food additives or sugar substitutes. Non-food products (often labeled as dietary supplements) containing less refined stevia ingredients are available, and some are even deemed “safe for consumption.” However, the FDA recommends waiting for more conclusive research before consuming large quantities of supplements containing stevia-derived ingredients other than Rebaudioside A.

In addition to Rebaudioside A, most FDA-approved stevia sweetener products also contain fructooligosaccharide, a sugar extracted from non-stevia fruit sources. Some studies show that fructooligosaccharide may actually promote the growth of healthy bacteria, relieve constipation, regulate lipid metabolism, and promote immune system health. Additionally, these sugars may be less detrimental to oral health than table sugar, and may help to treat glucose intolerance. Rebaudioside A and fructooligosaccharide are both approved by the FDA as food additives.

Although some empirical studies show no negative side effects of consuming unrefined stevia plant products and deem them “relatively safe” and “nontoxic,” the FDA has expressed safety concerns related to these products. Such concerns include negative effects on the reproductive, cardiovascular, and renal systems as well as blood sugar regulation issues. Other concerns include the stevia plant’s potential ability to damage genetic material, but independent scientific studies have determined that this type of gene damage is only possible in a laboratory environment, not in the human body. Stevia proponents also cite the plant’s inability to be digested (hence, the reason why it is calorie-free) as evidence that it simply passes through the body without causing any damage.

When it comes to sweeteners and food additives, Rebaudioside A is the only FDA-approved component of the stevia plant. Considering the inconclusiveness of existing research, it's good to consume unrefined stevia supplements and other non-food products cautiously. Good work keeping yourself informed before you ingest!