Stevia, an herb that grows in Brazil and Paraguay, has been touted as a natural sugar substitute for diabetics and others wishing to control sugar intake. Proponents say stevia has far fewer side effects than artificial sweeteners such as sucralose (Splenda) and aspartame (NutraSweet). Both the leaves and purified extracts of the plant are used as sweeteners. The stevia product approved for use as a supplement, not as a food, in the United States contains rebaudioside, a highly refined and purified extract. Like any drug, stevia, which the FDA classifies as "generally recognized as safe," or GRAS, can have side effects.
Gastrointestinal Effects
The most common side effects of stevia are related to the stomach and intestines. A feeling of fullness or nausea has been reported in a few people, but symptoms disappeared within one week, Memorial Sloan-Kettering Cancer Center, or MSKCC, reports.
Blood Sugar Levels
Stevia might lower blood glucose levels, according to several animal studies on rats, including one reported in the October 2005 issue of "Hormone and Metabolic Research." People who take anti-diabetes medications might need to lower their doses to avoid hypoglycemia, or abnormally low blood sugar levels. In animal studies, this effect was related to decreased glucose production in the liver and increased insulin sensitivity, the MSKCC website says. If you take anti-diabetic medications, talk with your medical practitioner before using stevia.
Blood Pressure
Stevia also might lower blood pressure. A double-blind, placebo-controlled human study conducted by the Taipei Medical College and affiliated Taipei Wan Fang Hospital in Taiwan appeared in the September 2000 issue of the "British Journal of Clinical Pharmacology." The year-long study of patients with high blood pressure found that those taking stevia saw their pressure drop more than those in the placebo group. Interestingly, this study found no effect in the stevia group on blood glucose levels. A second study reported by the same group in the November 2003 "Journal of Clinical Therapeutics" reported that systolic blood pressure dropped on average from 150 to 140 mm/Hg and diastolic from 95 to 89. Stevia might lower blood pressure by acting as a calcium channel antagonist, similar to the prescription drug Verapamil, Memorial Sloan-Kettering reports. If you take blood pressure medication, don't take stevia without discussing its effects with your doctor.
Muscle Weakness
Several people taking stevia have reported muscle pain and feelings of weakness or energy loss while using the sweetener. Symptoms cleared up within a week, according to MSKCC.
References
- Memorial Sloan-Kettering Cancer Center: Stevia
- Mayo Clinic: Stevia--Can it Help with Weight Control?
- "British Journal of Clinical Pharmacology"; "A double-Blind Placebo-Controlled Study of the Effectiveness and Tolerability of Oral Stevioside in Human Hypertension"; P. Chan et al; September 2000
- "Journal of Clinical Therapeutics"; "Efficacy and Tolerability of Oral Stevioside in Patients with Mild Essential Hypertension: a Two-year, Randomized, Placebo-Controlled Study"; M. Hsieh et al; November 2003
