Stevia, an herb native to South America, is cultivated for its leaves, which are used as a natural alternative to sugar. Stevia contains no calories and refined extracts of stevia are as much as 200 to 300 times sweeter than sugar. Stevia is used commercially as a sweetener in some parts of the world. In the United States, stevia is classified and sold as a food supplement.
Blood Pressure and Blood Sugar
Stevia may lower blood pressure and blood sugar, according to a U.S. study published in the April 2010 "Cardiovascular and Hematologic Agents in Medicinal Chemistry" journal. The study -- a review of previously published reports -- cited two long-term studies of 1 to 2 years in length that showed blood pressure-lowering properties of stevia and mentioned short-term studies that did not support the use of stevia for treating hypertension. The authors also noted poor quality of the studies that showed stevia lowered blood sugar and that this preliminary evidence warrants further research.
Other Sweeteners
A comparison of stevia with other sweeteners showed that stevia significantly reduced post-meal blood glucose levels compared to sucrose. The U.S. meta study -- a review of previously published reports -- published in the April 2010 "Cardiovascular and Hematologic Agents in Medicinal Chemistry" journal found that stevia use also resulted in lower post-meal insulin levels than either sucrose or the artificial sweetener aspartame. Additionally, volunteer participants did not consume more calories at the test meals that included stevia, in spite of the fact that stevia provides no calories, indicating stevia's potential weight loss effects.
Anti-inflammatory and Anti-cancer
Anti-inflammatory and anti-cancer effects were identified in stevia against skin cancer in a Japanese study published in the November 2002 "Biological and Pharmaceutical Bulletin." Four compounds isolated from stevia had strong anti-inflammatory activity in the study on mice. Additionally, the researchers noted that the mixture of active constituents markedly inhibited tumor production by the carcinogen 12-O-tetradecanoylphorbol-13-acetate.
Kidney Effects and Safety
Kidney filtration rate increased and reabsorption of glucose decreased in response to stevia, in a Brazilian study published in the May 2009 "Brazilian Journal of Biology." Stevia caused blood vessels and filtration tubules in the kidneys to expand, allowing the kidneys to filter more rapidly, leading to an increased loss of water, sodium and potassium than what occurs without the presence of stevia. In a separate study, published in the July 2008 issue of "Food Chem Toxicol," which used high levels of stevia on laboratory mice, the sweetener was deemed safe, with no adverse effects on the liver or kidneys.
References
- Pub Med: An evidence-based systematic review of stevia by the Natural Standard Research Collaboration
- Pub Med: Effects of stevia, aspartame, and sucrose on food intake, satiety, and postprandial glucose and insulin levels
- Biological and Pharmaceutical Bulletin: Inhibitory Effect of Stevioside on Tumor Promotion by 12-O-Tetradecanoylphorbol-13-acetate in Two-Stage Carcinogenesis in Mouse Skin
- Brazilian Journal of Biology: Steviol effect, a glycoside of Stevia rebaudiana, on glucose clearances in rats
- Pub Med: Subchronic toxicity of rebaudioside A
- Stevia.com: Questions & Answers about Stevia
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