What It Is: This natural, no-calorie sweetener, made from a South American plant, has been around for centuries. It's now in sodas and sports drinks, as well as tabletop packets (usually green), liquid drops, dissolvable tablets, and spoonable products, as well as baking blends. Among brand names, SweetLeaf is a sweetener made from stevia extract, and both Truvia and Pure Via are stevia-based. Some stores have generic stevia products.
The Scoop: Highly purified stevia extracts, which are what you find on the market, are generally recognized as safe. Some people find that stevia can have a metallic aftertaste. Whole-leaf stevia or crude stevia extracts aren't FDA-approved.
Acesulfame Potassium (Acesulfame-K or Ace-K)
What It Is: Two hundred times sweeter than sugar, acesulfame potassium is a man-made, no-calorie sweetener. You can find it in tabletop packets as Sunett or Sweet One, or in sugar-free gum, light juices, and light ice cream.
The Scoop: The FDA says that more than 90 studies support its safety.
What It Is: Thousands of types of foods are sweetened with aspartame -- aka NutraSweet and Equal. It’s a combo of two amino acids that provide sweetness with almost no calories.
The Scoop: Aspartame "is one of the most exhaustively studied substances in the human food supply, with more than 100 studies supporting its safety," the FDA states.
"An adult weighing 165 pounds would have to drink more than 19 cans of diet soda or consume more than 107 packets a day to go over the recommended level," the American Cancer Society says.
Some people have reported that aspartame gives them headaches or dizziness or affects their moods, but studies haven't linked those symptoms to aspartame. If you have phenylketonuria (PKU), a rare metabolic disorder, avoid aspartame, because it contains phenylalanine. Any product containing aspartame has a warning label about that.
What It Is: Saccharin has been around since the late 1800s, when a researcher spilled the chemical compound on his hand and realized it tasted sweet. It’s between 300 and 500 times sweeter than table sugar and best known as Sweet’N Low.
The Scoop: In the 1970s, saccharin got a warning label after lab tests in rats suggested a possible link to bladder cancer. "Since then, more than 30 studies demonstrated that the results found in rats were not relevant to humans, and that saccharin is safe for human consumption," the FDA's web site states. Saccharin no longer carries a warning label.