Just when you thought you had artificial sweeteners all figured out and had settled on a particular brand, the sweetener scene is changing again.

Yes, sweeteners have been back in the news. This time the focus is on sucralose, a new zero-calorie sugar substitute that was quickly approved by the U.S. Food and Drug Administration this past April. Marketed under the trade name Splendaª, sucralose will soon be found in Diet RC cola as well as other food products.

Sucralose is not only 600 times sweeter than sugar, it is also believed to be safe. The FDA reviewed data from more than 110 studies in humans and animals to identify possible toxic effects of sucralose and found none. Sucralose is also the only artificial sweetener to pass muster with the Center for Science in the Public Interest (CSPI), a consumer advocacy group which has been critical of other artificial sweeteners.

Sucralose is the fourth artificial sweetener approved for use in the United States; the others are saccharin, aspartame, and acesulfame potassium. While there is now more variety in the sweetener marketplace, there is also more to know and consider. To help you weigh your options, here is a quick rundown of the other major sweeteners.

A Bittersweet Battle Over Ace-K

On June 30, the FDA extended its approval of acesulfame potassium (sold under the trade name Sunett¨) to include use in liquid beverages. Although acesulfame potassium (ace-K, for short) has been around since 1988, when it was approved for use in table-top sweeteners (e.g., Sweet One¨, DiabetiSweetª), chewing gum, and dry-mix beverages and desserts, and later for six other food categories, this is the first time it has been given the all-important FDA go-ahead for liquid beverages.

But that isn't the end of the story. Every step of the way this sweetener has met with opposition from the CSPI, which publishes the Nutrition Action Healthletter. In 1996, CSPI petitioned the FDA to reject the use of ace-K in soft drinks and to withdraw all previously granted approvals for use in foods. The group asserted that the additive causes cancer in animals and may increase cancer in humans. CSPI's Senior Scientist Myra Karstadt indicates that "Hoechst's [the manufacturer] studies of acesulfame's carcinogenic potential were poorly designed, poorly executed, and poorly reported." CSPI's web site, www.cspinet.org, lists several U.S. cancer experts who also criticize Hoechst's studies.

But Nutrinova Inc., the maker of ace-K and a subsidiary of German chemical giant Hoechst, says the claims are ill-founded. "CSPI has brought their concerns to the FDA at least three times since 1988, and the FDA has refuted each one of their arguments," says Andrea Stine, a spokesperson for Nutrinova. "We feel the FDA is the gold standard for approving and reviewing the safety of food ingredients, and people should feel very, very comfortable that acesulfame potassium has gotten eight approvals from the FDA since 1988."

Ace-K has been consumed for more than 15 years and is used in more than 4,000 foods and beverages worldwide. "In more than 90 scientific studies, there have been no substantiated adverse effects," says Stine.

The Saccharin Debate

Saccharin has been on the market for nearly a century. Questions about the sweetener's safety first emerged in 1977 when Canadian toxicology studies suggested it caused bladder tumors in rats. When the FDA responded by proposing to ban saccharin, the public outcry in support of the sweetener caused Congress to impose a moratorium on any further action.

The debate on saccharin's cancer-causing potential still rages. More than 30 human studies have been completed finding no association between saccharin intake and bladder cancer in humans. However, other studies, according to the CSPI, have found a cancer link.

The National Toxicology Program (NTP), a division of the National Institute of Environmental Health Sciences, recently reviewed the data on saccharin. The NTP has decided to continue listing saccharin as a potential human carcinogen, requiring that all products containing the sweetener display a warning label.

Saccharin is currently approved by the FDA, the Joint Expert Committee on Food Additives of the World Health Organization, and the Scientific Committee for Food of the European Union, and endorsed by the American Medical Association, the American Diabetes Association, the Juvenile Diabetes Foundation, the American Dietetic Association, and the American Health Foundation.

Aspartame Rules Despite Concerns

Although aspartame (NutraSweet¨) hasn't been in the news lately, it is still one of the most hotly argued food additives ever to get FDA approval. Supporters of aspartame cite the more than 200 studies in animals and humans over the past 20 years that show no ill effects. Its critics claim it causes a variety of symptoms, including dizziness, brain seizures, and multiple-sclerosis-like syndromes. The Centers for Disease Control consider aspartame to be safe. Nevertheless, they note that some individuals may exhibit vague, but not dangerous, symptoms due to an aspartame sensitivity.

Aspartame is metabolized by the body and breaks down into its primary components, namely aspartic acid, phenylalanine, and methanol. Much of the controversy surrounding aspartame has focused on the effects of the latter two breakdown products.

Critics of aspartame claim that methanol, which is another name for wood alcohol, is a poison. Furthermore, they claim that methanol breaks down into formic acid and formaldehyde in the body. The latter substance is a known carcinogen.

The International Food Information Council Foundation (IFIC), a non-profit information organization in Washington, D.C. funded by the food and beverage industry, dismisses these claims, noting that methanol is a natural and harmless by-product of many commonly consumed foods. In a brochure entitled "Everything You Need to Know About Aspartame" the IFIC states, "The methanol produced by the metabolism of aspartame is identical to that which is provided in much larger amounts from fruits, vegetables, and their juices and is part of the normal diet."

Less controversial are the effects of phenylalanine. Persons born with a rare disease called phenylketonuria (PKU) can suffer from mental retardation if they ingest phenylalanine. PKU can be controlled by restricting dietary intake of the substance from all sources, both natural and that found in aspartame.

While the health effects are debated, one fact that is beyond question is that aspartame has been immensely popular. The sweetener quickly surpassed saccharin in popularity not long after it was introduced in 1981 and even encroached on sugar sales. But companies are beginning to find ways to capitalize on the public skepticism regarding aspartame and reduce the sweetener's market share. For example, Triarc, maker of Diet RC Cola, has begun aggressively marketing its sucralose-containing product as being aspartame free.

A Natural Alternative

If you prefer to avoid the artificial sweeteners and don't feel comfortable with sugar, even though it is now known to have no more of a glycemic effect than rice or potatoes, you might check out the herbal extract stevioside, which is available in many health food stores. It comes from the stevia plant, which is native to South America and a member of the chrysanthemum family, and has been used as a sweetener in Brazil, Paraguay, Japan, China, and other parts of Asia for many years. In the 1970s, the Japanese developed a method of refining the sweet glycosides out of the stevia leaf, creating stevioside, which is 300 times sweeter than sugar. Because it is considered a dietary supplement, stevia is also not regulated by the FDA.

As for its taste, stevia is very potent, so just a small pinch creates a lot of sweetness. Depending on the preparation, there may be a definite licorice-like aftertaste.

A Sugar that Lowers Blood Sugar?

One of the most interesting sweeteners in the news is D-tagatose, a compound developed by Biospherics Inc., which the company says is "a natural, full bulk sugar with an excellent taste virtually indistinguishable from that of table sugar." By all reports, it is virtually identical to sugar in that it withstands the heat of cooking, browns like sugar, has the same bulk as sugar (one teaspoon of D-tagatose equals one teaspoon of sugar), and has the same taste and texture as sugar. Most amazingly, it appears to have no effect on blood sugar levels.

In fact, researchers at the University of Maryland School of Medicine have been studying the compound and testing it on type 2 patients. Preliminary evidence suggests that D-tagatose may cause "a reduction in average blood sugar values," according to researcher Dr. Thomas Donner, and "may be a useful adjunct in the management of non-insulin-dependent diabetes."

In February the licensing rights to D-tagatose were turned over to MD Foods Ingredients of Denmark, which will market the product in Australia and other Pacific Rim countries under the trade name Sugareeª. MD Foods is also applying for entry of D-tagatose into the U.S. market as a GRAS (Generally Recognized as Safe) product under FDA regulations. Look for it on supermarket shelves in the near future.