In December 2008, the U.S. Food and Drug Administration (FDA) approved Rebiana, also known as Reb A or rebaudioside A, found in the stevia leaf. Stevia is derived from the leaves of a South American shrub and has been used to sweeten foods in Brazil, Paraguay, Japan, South Korea and China for many centuries. Reb A is one of two compounds; the other being stevioside, found in the stevia leaf. Reb A is less bitter and sweeter than stevioside. Rebiana is approved by the FDA as "generally recognized as safe" (GRAS).
Stevia previously had been sold only in health food stores as a dietary supplement. Due to some studies indicating that stevia may reduce fertility or cause genetic mutations that could lead to cancer, it was banned as a food ingredient in the US and approved only as a dietary supplement. Supplements, similar to GRAS substances, are not required to be scrutinized as much as foods are.
Today, Truvia and PureVia are available in packets similar to other sugar substitutes such as Splenda, Equal and Sweet n' Low, and will soon be seen in a growing number of sugar-free products. The main ingredients are Reb A (from the stevia leaf) and Erythritol (a sugar alcohol with no effect on glucose levels and little or no laxative effect).
Truvia can be found at Whole Foods, Walmart and other grocery stores.
PureVia can be found at grocery stores.
Use moderately. Moderate use is 4 servings a day: 4 packets or food servings similar to food exchanges (8 ounce drink, etc.)