What it is: Derived from a shrub; now available in leaf form (ground or whole leaf) and as a chemically refined liquid or powder concentrate. Usually sold in the supplement section. The raw leaf is 60 times sweeter than sugar; in concentrated form, stevia is 150 to 300 times sweeter than sugar.
Health impact: In South America and Asia, people have used raw-leaf stevia safely for centuries as a flavor enhancer. With zero calories, it exerts no impact on insulin levels (some studies suggest stevia may actually help control insulin levels). Late last year, the FDA granted "no-objection" status to Coca-Cola and PepsiCo to use stevia-based products in beverages.
Best in: Ideal for sweetening tea, lemonade, or other liquids. Lacks bulk, so it's trickier for baking -- works in cookies, granola, and pies, but not as well in breads, cakes, or anything where texture matters.
How to use: In baking, replace 1 cup sugar with 1 teaspoon stevia powder (or liquid), plus 1/3 cup of a bulking agent, such as egg whites, applesauce, mashed bananas, pumpkin puree, or yogurt; increase liquid by 2 Tablespoons. Can add a bitter aftertaste, so go easy.