I'm not a fan of artificial sweeteners. I don't care for the way they taste, and one variety in particular gives me headaches. So imagine my dismay when I recently shopped for my favorite chewing gum and found its tiny but satisfying amount of real sugar had been replaced with aspartame, one of the leading fake sweeteners on the market. Hello, headache.

I'm apparently in the minority when it comes to artificial (or synthetic, or non-nutritive, or high-intensity) sweeteners; I was hard-pressed to find a pack of gum or breath mints that was conventionally sweetened. According to the American Dietetic Association, nine out of 10 Americans uses artificial sweeteners; the Calorie Control Council, a trade organization representing manufacturers of low- and reduced-calorie foods and beverages, reports that in 2007, 194 million American adults consumed low-cal or sugar-free foods and beverages. That's up from 180 million in 2004.

Taste aside, the benefits of reduced-calorie sweeteners are obvious: They allow people to indulge a sweet tooth without packing on pounds. Aspartame-sweetened Extra chewing gum, for instance, is the official sweet treat for "The Biggest Losers" TV show and is credited on the show's Web site as having helped winning contestants curb their urge to snack on high-calorie treats. Artificially sweetened foods and drinks also help people avoid "nutrient displacement," which can occur, for example, when they fill themselves up on sugary foods that don't have any nutritional value at all (such as non-diet soda).

But some studies have suggested that artificially sweetened foods and beverages may in some cases contribute to people becoming overweight. It's thought that perhaps the body gets confused: The sweet taste signals calorie delivery, but when those anticipated calories don't materialize, the body might overcompensate and prod people to overeat.

The hot news in the realm of sweeteners is the introduction of stevia-based Truvia to supermarket shelves.

Stevia, derived from a South American shrub, has been used as a sweetener in some cultures for centuries. It has been available in health-food stores here for a while, but its use is expected to become widespread now that the Food and Drug Administration has deemed the stevia-plant derivative rebaudioside A, or rebiana, to be a "generally recognized as safe," or GRAS, dietary supplement. Both Coca-Cola and Pepsi have stevia-sweetened soft drinks in the pipeline. And the Truvia folks are heavily promoting the notion that their product is "natural."

But as Michael Jacobson, executive director of the food-industry watchdog group Center for Science in the Public Interest, points out, "natural" doesn't necessarily mean "safe." Just ask Socrates: The hemlock that killed him was perfectly natural, too.

Jacobson says stevia hasn't been adequately studied in labs, and CSPI's Web site says its derivates should be avoided or used with caution.

Of the other non-caloric sweeteners on the market, CSPI calls sucralose safe to use; the organization urges caution about the others for their murky testing histories.

On the other hand, the American Dietetic Association embraces all of the current high-density sweeteners. "The bottom line is that they're sold in the United States with the guiding principle that they're safe," says Dawn Jackson Blatner, an ADA spokeswoman. "Any consumer can feel confident that the government has said they're safe."

"Should you be eating them?" Blatner continues. "That's a matter of personal preference. If you like the way they taste," then they can be part of your balanced diet.

Despite CSPI's call for more and better science and in light of Americans' ever-expanding waistlines (and the attendant health problems), Jacobson says, "I'd rather people drink diet soda than regular soda. You've got to weigh the speculative risk of cancer against the certain risks of obesity and calorie displacement."