As more Americans shy away from sugar, artificial sweeteners have stepped in to fill the gap in people's favorite recipes, with more than 6,000 products manufactured with aspartame.

However, on July 13, the cancer research arm of the World Health Organization released a report categorizing the artificial sweetener as "possibly carcinogenic to humans."

"The assessments of aspartame have indicated that, while safety is not a major concern at the doses which are commonly used, potential effects have been described that need to be investigated by more and better studies," Dr. Francesco Branca, director of the WHO Department of Nutrition and Food Safety, said in a statement.  

The WHO's International Agency for Research on Cancer examines the cancer-causing potential of substances. A second group — the Joint FAO/WHO Expert Committee on Food Additives — made up of members from both WHO and the Food and Agriculture Organization of the United Nations, oversees recommendations about how much of a product is safe for humans to consume. 

The food additives committee determined that an "acceptable daily intake" of aspartame is 40 milligrams per kilogram of body weight. 

Aspartame has been approved by the U.S. Food and Drug Administration for use in food products, with the agency concluding the additive is "safe for the general population." But questions have lingered about aspartame's safety, with one 2021 research paper, published in the peer-reviewed journal Nutrients, noting that "the results of its long-term use remain difficult to predict."

What is aspartame?

Aspartame is a dipeptide artificial sweetener, meaning it is composed of two amino acids (aspartic acid and phenylalanine) joined together by a peptide bond. The artificial sweetener, which is 200 times as potent as regular granulated sugar, entered the market as a low-calorie sweetener in 1981. Brand names include Nutrasweet, Equal and Sugar Twin. Since then, it has become a key ingredient in foods and beverages across North America, Asia and Europe, data from the scientific journal Nutrients shows.

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According to several studies, aspartame does not impact blood sugar or insulin levels, making it a popular sugar substitute in foods for diabetics. Manufacturers have also used aspartame in reduced-sugar and sugar-free snacks, condiments and beverages amid research that has linked excess sugar consumption to various cancers. 

Foods that contain aspartame

Here are some common foods and beverages that contain aspartame: 

• Zero-sugar or diet sodas, including Diet Coke
• Sugar-free gums, such as Trident gum
• Diet drink mixes, including Crystal Light
• Reduced-sugar condiments, such as Log Cabin Sugar Free Syrup
• Sugar-free gelatin like Sugar-free Jell-O
• Tabletop sweeteners sold under brand names including Equal and Nutrasweet

Neither Coca-Cola, maker of Diet Coke, nor other manufacturers of foods containing aspartame immediately returned requests for comment.

To be sure, specific sweeteners used in low-sugar products vary, and companies sometimes change ingredients. To get the most accurate information, consumers should check the ingredient lists on individual products to confirm whether or not it contains aspartame.

Is aspartame dangerous?

While numerous studies have determined aspartame to be safe in moderation, some research has linked aspartame consumption to cancer. One observational study of more than 100,000 adults in France concluded that individuals who consumed larger amounts of artificial sweeteners, especially aspartame, had a slightly elevated risk of cancer. 

Aspartame may also cause headaches, seizures and depression, some studies have shown. 

The FDA and American Cancer Society, however, both still deem aspartame safe for human consumption.  

According to the FDA's acceptable daily limit for artificial sweeteners, an adult weighing 150 pounds would have to ingest more than 18 cans of zero-sugar soda a day to exceed that amount and increase their risk of negative health consequences from aspartame.

Robert Rankin, president of the Calorie Control Council, an international association representing the low- and reduced-calorie food and beverage, said there was context missing from the "misleading claims" from the IARC.

"Consumers deserve facts, and the fact is aspartame is safe and one of the most widely studied food ingredients, which is why the Calorie Control Council is gravely concerned about any unsubstantiated and misleading assertions that contradict decades of science and global regulatory approvals," he said in a statement to CBS News.

This story has been updated to correct the previous inclusion of Smucker's on the list. Smucker's said it does not use aspartame in its low-sugar jams.

In:
• Health
• Aspartame
• Food and Drug Administration
• World Health Organization
• FDA