Q: You’ve recommended stevia as a sweetener in the past. I’ve heard that it soon may be approved to sweeten all kinds of foods. Can you update me on its use and any safety concerns?

A: Stevia comes from an herb in the chrysanthemum family called Stevia rebaudiana. It is native to Paraguay, also grows in Brazil and Argentina, and is cultivated in China. The leaves have been used for centuries by native peoples to make sweet teas or to sweeten other foods, with no evidence of harm. It is available in the United States and the European Union as a dietary supplement and is sold here in whole-leaf form or as stevioside, the sweet extract that is sold as a granular white powder. The powder has very few calories but is so sweet that to use it, you must dissolve it in water, and then dispense the solution by drops. A teaspoon of the liquid is equivalent in sweetness of a whole cup of sugar. Stevia is safe for diabetics and is widely used as a non-nutritive sweetener around the world.

Over the years, the Food and Drug Administration has turned down several requests to use stevia in foods. The agency cites a handful of studies suggesting that large amounts of stevia could be harmful. One study showed that high doses reduced sperm production and might cause infertility in male rats; another showed that when female hamsters were fed large amounts of a stevia derivative, they had smaller babies. Other studies indicated that stevia might be carcinogenic and might disrupt the metabolism.

None of these possibilities has been proved, and stevia has an excellent safety profile in Japan, where it has been used for more than 30 years in foods.