The World Health Organization’s International Agency for Research on Cancer announced Thursday that the artificial sweetener aspartame, commonly found in Diet Coke and other sugar-free foods, is a possible carcinogen.
However, a second WHO group, the Expert Committee on Food Additives, did not change its threshold for the daily amount of aspartame that is safe to consume: 40 milligrams per kilogram of body weight for adults who weigh about 154 pounds. Added up, that’s the amount in about 14 cans of Diet Coke. The Food and Drug Administration has a slightly higher daily limit of 50 milligrams per kilogram of body weight for an adult weighing about 132 pounds.
“It’s a slight warning to people, but it’s not ‘don’t eat,’” Barry Popkin, professor of nutrition at the University of North Carolina Gillings School of Global Public Health, said of the WHO decision. «Consume moderate levels and you’ll be fine.»
Found in more than 5,000 foods and beverages, aspartame is much sweeter than sugar. In 1974, the FDA approved its use as a tabletop sweetener and an ingredient in chewing gum, cereals, instant coffee, dairy products and other items. Common foods and drinks with aspartame include:
- Tabletop sweeteners, including NutraSweet, Equal, and Sugar Twin.
- Drinks and drink mixes, such as Diet Coke, Coke Zero, Diet Snapple, Fanta Zero, Sprite Zero, Crystal Light, and Wyler’s Light.
- Sugar-free gum, including Trident, Extra, Wrigley’s, and Mentos gum.
- Gelatin-based products, including Sugar Free Jell-O and Royal Gelatin.
- Syrups, including Mrs. Butterworth’s Sugar Free Syrup and Log Cabin Sugar Free Syrup.
Following the WHO announcement, the FDA said in a statement that it «disagrees with the IARC’s conclusion».
“FDA scientists have no safety concerns when aspartame is used under approved conditions,” the agency said.
What the research says about cancer risk and aspartame
The WHO placed aspartame in one risk category below two others: «carcinogenic to humans» and «probably carcinogenic.» other substances Included in the “possible carcinogen” category are aloe vera, pickled vegetables, and nickel.
Previous research on aspartame’s link to cancer has not yielded conclusive evidence that it causes disease, and many studies investigating links between cancer and artificial sweeteners have been based on animals, not humans, Popkin said.
TO study 2020, for example, found a higher incidence of leukemia and lymphoma in mice consuming aspartame, but the doses nearly quadrupled the weight of the mice, Popkin said, making them a poor benchmark for human risk. Meanwhile, studies from the 1980s found that aspartame did not cause brain tumors either bladder cancer in rats
TO study 2022 However, out of more than 100,000 adults in France, it found that consuming large amounts of artificial sweeteners was linked to a slightly increased risk of cancer.
Artificial sweeteners can bring other health risks
Although the WHO announcement may seem to imply that aspartame is worse than other artificial sweeteners, Popkin said, it could all be linked to negative health effects.
«Frankly, I think it’s such a trivial difference that all diet sweeteners should be treated equally,» Popkin said. “But if you’re consuming 10 Diet Cokes or 10 Diet Pepsis in a day, you shouldn’t. You have to cut back, because that’s too much, and that moves toward potential carcinogen levels.»
Previous research has linked artificial sweeteners with a higher chance of heart disease, high blood pressure, diabetes and obesity.
In May, the WHO advised against consuming artificial sweeteners as a weight loss strategy, as they have not been found to reduce body fat in the long term.
“If you drink 32, 64 ounces of soda a day, it’s probably better to have these artificially low-calorie sweeteners than to drink that much added sugar,” said Dariush Mozaffarian, a professor of nutrition at Tufts University. “On the other hand, I wouldn’t think of these as simply 100% safe. I would avoid them as much as possible.»
The 2022 study in France found that people who consumed aspartame had an increased risk of stroke and that replacing added sugar with artificial sweeteners did not reduce the risk of heart disease.
In another study published last year, Israeli researchers found that artificial sweeteners altered the gut microbe populations of participants.
«It’s best to eat a natural, healthy diet with naturally sweet foods,» Mozaffarian said. «So I think of these artificial sweeteners as a bridge away from very high doses of added sugar, but not necessarily a safe switch.»
CORRECTION (July 14, 2023 5:55 PM ET): An earlier version of this article erroneously stated the WHO recommended limit for aspartame consumption. That’s 40 milligrams per kilogram of body weight, not 40 milligrams total.