Stevia has promise, but use with caution

Stevia, an extract from a South American shrub, is hundreds of times sweeter than sugar -- and practically calorie free. It’s been used for centuries to sweeten herbal teas in South America, and for the last 20 years, it’s also been widely used as a commercial sweetener in Japan and Brazil. It’s not an approved food additive in the U.S., but it is sold in health food stores as a dietary supplement.

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Uses: Stevia is often used as a replacement for sugar. And in Brazil, it’s been used in attempts to treat diabetes. Some people also use it to lose weight, relieve heartburn and prevent plaque build-up on teeth.

Dose: A quarter teaspoon of stevia extract is equivalent to about a cup of sugar. Recommended doses for treating different conditions vary, but most manufacturers suggest about a gram a day. The supplement is available in powder and pill form.

Precautions: People allergic to ragweed may be sensitive to stevia. There’s not much information on the effects of using frequent large doses, but even small doses may interact with medications taken for diabetes.

Research: Studies in rats have shown that high doses of stevia lower sperm counts in males, lower the birth weights of females’ offspring, and cause kidney damage. A few human studies suggest that the herb may be effective in lowering blood pressure and treating Type 2 diabetes, but more research is needed before its effects can be confirmed.

Dietary supplement makers are not required by the U.S. government to demonstrate that their products are safe or effective. Ask your doctor for advice on selecting a brand.

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-- Elena Conis