Sugar substitutes and alternative sweeteners promise flavor with few or no calories. Also on the market are "natural" sweeteners such as Whey Low. It's made from fructose, the sugar found in fruit; sucrose, ordinary table sugar; and lactose, the non-sweet-tasting sugar found in dairy products.

At 4 calories per teaspoon, Whey Low pours and bakes just like sugar, but with 75 percent fewer calories.

Blue agave nectar is another natural sweetener that is growing in popularity. It's extracted from a cactuslike plant. But at 15 calories per teaspoon, it has just one fewer calorie than table sugar; six fewer than honey. Agave nectar is touted for being sweeter tasting than either sugar or honey, so that smaller amounts can be used. It is also purported to have a lower glycemic index, which means it may raise blood sugar less than the others.

Calories are one thing. Safety is another. In 1970, the Food and Drug Administration banned cyclamates, a widely used sugar substitute, because of cancer concerns. In 1977, a Canadian study found that saccharin -- the sweetener still found in Sweet'N Low -- caused bladder cancer in rats. The FDA considered banning saccharin but Congress stepped in to give the sweetener a reprieve and has extended a moratorium on its ban several times since then.

In 2004, the American Dietetic Association reviewed the use of sweeteners and concluded that "consumers can safely enjoy a range of nutritive and non-nutritive sweeteners when consumed in a diet that is guided by current federal nutrition recommendations."

Since then, some concerns have arisen about two sugar substitutes: acelsulfame K and aspartame.

Aspartame is marketed as NutraSweet and Equal, and found in a wide range of products from diet drinks to sugar-free ice cream. Aspartame contains amino acids -- the building blocks of protein -- and methanol, an alcohol. It isn't heat stable so it doesn't do well in baking. An Italian research team found lymphoma and leukemia among female rats in a long-term study of aspartame.

Acesulfame K, also sold as Sunnett, is not metabolized by the body and so contains zero calories. It's found in baked goods, diet soft drinks, sugar-free gum and Sweet One, a sugar substitute for baking. In 1996, the Center for Science in the Public Interest urged the FDA to require better testing before permitting acesulfame K in soft drinks. Large doses of a breakdown product from acesulfame K have been shown to affect the thyroid of rats, rabbits and dogs, CSPI notes.

Manufacturers, the FDA and the Calorie Control Council say that these products are safe. But in the May issue of Nutrition Action, CSPI called these products and saccharin either unsafe or poorly tested. The only artificial sweetener to get a "safe" grade from the consumer advocacy group is sucralose, better known as Splenda.

Bottom line: If you're looking for sweetness with fewer calories, reach for a variety of products to hedge your nutritional bets.

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