Health Benefits and Risks of Stevia

Author: Winston Craig, MPH, PhD, RD.
stevia

Stevia rebaudiana flowers  Photo by Ethel Aardvark

Stevia rebaudiana, commonly known as sweetleaf, sugarleaf, the sweet herb of Paraguay, or simply stevia, has remarkably sweet leaves. At a time when alternative sweeteners are in strong demand, stevia appears on stage as a big player. This sugar substitute is natural (non-synthetic) and has zero calories.

In addition, extracts of stevia are up to 300 times sweeter than sucrose, and stevia’s taste lasts longer than sucrose. The sweet taste of stevia is due to two similar glycosides, stevioside and rebaudioside A, found in the leaves. These compounds are heat stable and acid stable.

For centuries, residents of Brazil and Paraguay have used stevia as a sweetener in medicinal teas for treating various ailments, and as a treatment for type II diabetes. And now, a recent one-year clinical trial revealed that hypertensive individuals who consumed 250 mg of stevioside three times a day, experienced a 10% drop in blood pressure.

Stevia has a negligible effect on blood glucose, so it is attractive as a natural sweetener for the management of diabetes and metabolic syndrome, and for use in carbohydrate-controlled diets. The Japanese, Chinese, and Koreans have used stevia in foods and soft drinks for many years as an alternative to the artificial sweeteners, cyclamate and saccharin, which are suspected carcinogens. The wide use of stevia has been without any apparent harmful effects.

In 2006, the World Health Organization evaluated stevia and found no evidence that its sweet compounds, stevioside and rebaudioside A, have any carcinogenic activity. Furthermore, the report noted that stevioside shows some evidence of beneficial effects in patients with hypertension or with type-2 diabetes. The report concluded that further study was needed to determine proper dosage.

Truvia is a tabletop sweetener derived from stevia, which is soon to be released by Cargill (the leading producer of corn syrups), while Coca-Cola plans to obtain approval to use it by 2009 to sweeten their soft drinks. On the other hand, Whole Earth Sweetener (the maker of the sweetener Equal) will soon be releasing PureVia, another tabletop sweetener derived from stevia, with Pepsi-Cola hoping to add it to their beverages next year. Both Truvia and PureVia are more than 95% rebaudioside A.

Concerns about the safety of stevia still exist in the US where it was banned as a food additive in the early 1990’s, but then allowed to be used as a dietary supplement. The most recent studies seem to suggest stevia is safe, but there is a lack of human research to determine long-term risks. Both Coca-Cola and Pepsi-Cola are conducting studies in other countries in an effort to gain approval to use stevia as a food additive in the United States and Europe.

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