Nutrition Articles

The Science Behind Stevia

How Safe is This Trendy Sweetener?

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The sweetener stevia has plenty of dedicated followers. Who can blame them? For years, food and supplement manufacturers have advertised stevia as all natural, calorie free and safe for people with diabetes. To many people, stevia seems like a win-win: It sweetens food without adding calories, and it seems to be a healthy alternative to artificial sweeteners. But can you really believe all the hype?

The History of Stevia: From Supplement to Sweetener
Stevia is derived from the leaves of a South American shrub called Stevia rebaudiana. Its green leaves contain a substance that is 250-300 times sweeter than table sugar. The leaf extracts have been used for years in Brazil, Paraguay, Japan, South Korea, and China to sweeten foods in small to moderate amounts.

About 40 years ago, scientists began to study stevia in a laboratory setting. Some studies showed that stevia may reduce fertility or cause genetic mutations that could lead to cancer. In the 1970s, it was banned as a food ingredient in the United States. Then in 1994, the Dietary Supplement Health and Education Act made it legal to sell stevia in the United States as a dietary supplement only. Unlike foods, supplement manufacturers are not required to prove that their products are safe for consumption. For more than a decade, stevia powders, liquids and extracts were sold, usually in health food stores, as supplements, not foods. During this time, companies could not sell or market stevia as a food or an ingredient in any food product.

In 2004, the Joint Expert Committee on Food Additives of the Food and Agriculture Organization of the United Nations and the World Health Organization, an international regulatory authority, re-evaluated the research on stevia and requested additional information from ongoing toxicological and clinical studies. (To see a PDF version of that report, click here.)

There are two main sweetening chemicals in the stevia leaf: Rebaudioside A (also called Reb A or Rebiana) and stevioside. These two purified forms have received the most recent research. The July 2008 journal Food and Chemical Toxicology published eight studies on stevia. (You can obtain abstracts from these published studies through www.pubmed.com.) One report showed no reproductive toxicity in rats exposed to the sweetener for two generations, and two human studies showed that 1,000 milligrams of Rebaudioside A per day was safe for healthy adults, as well as those with Type 2 diabetes. They did not report on stevioside.

Around this time, several food manufacturers petitioned the U.S. Food and Drug Administration, stating that they consider Rebaudioside A (the highly purified extract of stevia) to be "GRAS" (Generally Recognized as Safe). When the FDA adds a food (or ingredient) to the GRAS list, it can be sold in foods and as a food product, even without prior FDA approval and without definitive proof that the food actually is safe.

In December 2008, the FDA concluded that Rebausioside A, the highly purified form of the leaves of the stevia plant, could have GRAS status as a general-purpose sweetener in foods and beverages. That means that stevia is no longer a supplement. You can now find it in the baking aisle, next to other sugars and artificial sweeteners. It is also an ingredient in some foods and beverages, used much like artificial sweeteners are, in diet soda, diet drinks, pudding, yogurt and other food products.
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About The Author

Becky Hand Becky Hand
Becky is a registered and licensed dietitian with almost 20 years of experience. A certified health coach through the Cooper Institute with a master's degree in health education, she makes nutrition principles practical, easy-to-apply and fun. See all of Becky's articles.

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