Stevia Side Effects and Warnings

Safety Issues

Animal tests and the extensive Japanese experience with stevia suggest that this is a safe herb. ¹ Based primarily on the apparently incorrect belief that stevia has been used traditionally to prevent pregnancy, ² some researchers have expressed concern that stevia might have an antifertility effect in men or women. However, evidence from most (though not all) animal studies suggests that this is not a concern at normal doses. ^{3 4} 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.