Don’t know which little packet to choose? Here’s a quick primer on the big three—plus the newcomers stevia  and agave nectar. All of them are approved by the Food and Drug Administration, but they do vary in flavor and uses, so you may find you need to do a taste test of your own.

Saccharin
Brands: Sweet’N Low and Sweet Twin
Sweetness: 200 to 700 times sweeter than sugar
Taste: Some people report a bitter aftertaste.
Safety: First produced in 1879, saccharin is the oldest of the artificial sweeteners. In 1970, a study in rats found that the sugar substitute was associated with bladder tumor growth, resulting in an eat-at-your-own-risk warning on the pink package. Years later, however, the warning was revoked as more than 30 human studies reported no saccharin-tumor connection.
How to cook with it: The Sweet’N Low brand sells packets as well as a bulk version for baking, a liquid formula, and a brown sugar blend. When baking, replace 1 cup of sugar with 24 packets, 2 tablespoons of saccharin liquid, or 1 cup of brown sugar saccharin.

Aspartame
Brands: Equal, NutraSweet, Natra Taste
Sweetness: 180 to 200 times sweeter than sugar
Taste: There’s no aftertaste associated with aspartame, though some say it has an unnatural flavor.
Safety: Search the Web for aspartame’s side effects and you’ll find stories about its purported link to cancer, dementia, headaches, and depression. Most scientists (as well as the American Diabetes Association) maintain that the powder is a safe alternative to sugar for people with diabetes. One caveat: Aspartame contains phenylalanine, which can be harmful to people with the rare disease phenylketonuria and should be avoided by them.
How to cook with it: High temperatures can diminish aspartame’s sweetness, so even though some brands (like Equal) sell bulk versions, most chefs avoid
baking with them.

Sucralose
Brand: Splenda
Sweetness: 600 times sweeter than sugar
Taste: Though some sugar purists say an aftertaste lingers, most sweetener fans maintain Splenda is the most natural tasting of all.
Safety: Since Splenda is the newest artificial sweetener to hit the market, there are fewer long-term studies of it than of saccharin and aspartame. That said, the FDA says that Splenda is safe.
How to cook with it: Splenda sells various baking products, including a granular version that measures cup for cup with sugar. If you use the half sugar blend or half brown sugar blend, replace a cup of sugar with a half cup of the blend.

Stevia
Brands: Truvia, PureVia, SweetLeaf, Stevia in the Raw, Sun Crystals sugar-stevia blend
Sweetness: 250 to 300 times sweeter than sugar
Taste: Some people say the sweetener derived from the whole leaf of the stevia plant leaves behind a licorice taste. Brands that use a purified portion of the leaf known as rebaudioside A have less of an aftertaste.
Safety: Stevia has been used as a sweetener in Japan for years, but the FDA had previously banned its use because of reports of reproductive problems in lab animals. In late 2008, the FDA approved the purified part of the stevia leaf for American consumption. Look for that form—rebaudioside A—in the list of ingredients when purchasing stevia.
How to cook with it: Each stevia brand recommends its own sugar-to-stevia ratio (so check your brand’s Web site), and some brands sell the sweetener in liquid or bulk form. A good start is to replace a cup of sugar with 24 packets of stevia.

Agave Nectar
Brands: Wholesome Sweeteners, Madhava, and Volcanic Nectar, among others
Sweetness: Somewhat sweeter than sugar, so use between a quarter and an eighth less agave nectar than if you were cooking with regular sugar.
Taste: The lighter, golden version tastes syrupy while the darker, amber variety has a more intense honey flavor.
Safety: Agave nectar isn’t carbohydrate or calorie free—it has the same amount of calories and carbs as sugar. But since it’s a food with a low glycemic index, the syrup won’t raise your blood glucose levels as much as sugar or honey do. Plus, it’s sweeter than sugar, so you’ll use less.
How to cook with it: Sweetening with agave nectar is simple if you’re swirling it into coffee. Things get more complicated when you start baking with the syrup. To adjust a recipe, replace each cup of sugar with two-thirds to three-quarters cup of agave nectar, then reduce all other liquids in the recipe by a quarter. Lower your oven temperature by 25 degrees to prevent burning, and shorten the cooking time on cookies by 3 to 5 minutes and cakes by 7 to 10 minutes.