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Meet stevia, nicknamed the "sugar herb." Once the well-kept secret of health-food aficionados, stevia (pronounced STEE-via) is fast becoming the rage with the sugar-shunning crowd in part because of the popularity of low-carb, high-protein diets, which discourage sweets.

"The public is still uncomfortable with artificial sweeteners and is looking for natural alternatives," says Ray Sahelian, a general practitioner in Marina Del Ray, Calif., and co-author of The Stevia Cookbook: Cooking With Nature's Calorie-Free Sweetener (Avery Publishing, $12.95). "Stevia is definitely spreading into the public, and I have seen a rise over the last two years of people who are familiar with it."

Word of mouth has popularized the plant, now available at garden centers and nurseries across the country.

At Wisdom Herbs in Mesa, Ariz., the country's largest processor of stevia, sales jumped from $150,000 in 1977 to $5 million in 2000 — half of U.S. sales last year. "It's tremendous stuff, and we've had positive feedback and lots of inquiries about it," says Michael Wood, vice president of Herb Herbert's Traditional Herbs in Valencia, Calif. "People are always surprised how really sweet it is, but the word is finally getting out."

Recognized in botanical circles as Stevia rebaudiana, the little green plant native to Paraguay is the planet's sweetest known natural substance; the raw leaves have been used for centuries in South America. Stevia contains a white crystalline compound called stevioside, the molecule that makes the herb's leaves 10 to 15 times as sweet as table sugar, although extracts range from 100 to 300 times as sweet. Proponents say it contains virtually no calories, doesn't raise blood-sugar levels or promote tooth decay, and lacks the chemical aftertastes of many artificial sweeteners, though the leaf has a slight licorice taste.

For those who opt to grow their own, stevia thrives in warm temperatures and well-drained soil. (Seeds are hard to find, but many nurseries stock the plants, priced at $2 to $6.) Mature leaves can be dried and ground or crushed into a green powder that can be used in cooking and to sweeten beverages. Infusions are produced by steeping leaves in boiling water or alcohol. Processed stevia ($8 to $15) — the kind you buy at health-food stores — comes in a concentrated powder or liquid.

Nelinda James, a gardener in Spring Hill, Fla., says she makes a great Key lime pie using part stevia and part sugar. "Since we're in our 50s, we had concerns about high sugar intake, but also serious concerns about the aspartame we were using. Stevia just seemed like a good, natural thing to try."

The Food and Drug Administration didn't allow stevia into the country until 1995, with the provision that it be sold as a dietary supplement, not as a sweetener. Stevia has been used in Japan for more than 30 years.

"I use it in pies, salad dressings and in my herbal teas," says Kathleen Suit of Bellingham, Wash., a stevia devotee for three years. "I don't use sugar anymore at all."