In the early 1970s, a consortium of Japanese food manufacturers developed stevia extracts for use as a zero-calorie sugar substitute. Subsequently, stevia extracts became a common ingredient in Asian soft drinks, desserts, chewing gum, and many other food products. Extensive Japanese research has found stevia to be extremely safe. However, there have not been enough US studies for the FDA to approve stevia as a sugar substitute. Without identifying it as such, stevia is nonetheless widely used by savvy manufacturers to sweeten commercial beverage teas and other products.
Although stevia is best known as a sweetener, when stevia extracts are taken in very high doses they may reduce blood pressure, according to two large Chinese studies.
What Is the Scientific Evidence for Stevia?
Stevia is sold as a powder to be added to foods as needed for appropriate sweetening effects. It tastes slightly bitter if placed directly in the mouth. In liquids, though, this is generally not noticeable, and most people find the taste delightfully unique.
In the studies showing an effect on blood pressure, stevia was given as a standardized extract supplying 250-500 mg of stevioside 3 times daily (a dose considerably higher than any reasonable use of stevia as a sweetener).
The two studies described above in which use of very high dosages of a stevia extract led to reductions in blood pressure raise at least theoretical concerns about stevia's safety. In theory, the herb could excessively reduce blood pressure in some people. Furthermore, if stevia can reduce blood pressure, that means that it is, in some fashion, acting on the cardiovascular system.
Since sugar substitutes are meant to be consumed in essentially unlimited quantities by a very wide variety of people, the highest levels of safety standards are appropriate, and unknown effects on the heart and blood circulation are potentially worrisome. This concern is somewhat mitigated by the fact that the daily dose of stevioside used in those studies was considerably higher than is likely to be consumed if whole stevia is used for sweetening purposes. Reassurance also comes from the study that found no effect with a dose of 15 mg/kg per day.
Safety in young children, pregnant or nursing women, or those with severe liver or kidney disease has not been conclusively established. Because of the concerns raised in the previous paragraph, individuals with cardiovascular disease should use high doses of stevia extracts only under physician supervision.
- Reviewer: EBSCO CAM Review Board
- Review Date: 07/2012 -
- Update Date: 07/25/2012 -