What to know about aspartame following the WHO’s assessment

The World Health Organization’s (WHO) new assessment of the safety of the common artificial sweetener aspartame has ignited a debate over just what consumers should do.

Two groups tied to the WHO — the International Agency for Research on Cancer (IARC) and the Joint Expert Committee on Food Additives (JECFA) — issued somewhat diverging conclusions Thursday in regard to aspartame, an extremely popular additive most often associated with diet foods.

The IARC determined that the sweetener was “possibly carcinogenic,” while the JECFA said it found “no convincing evidence from experimental animal or human data that aspartame has adverse effects after ingestion.”

The studies did not produce a change in the recommended daily intake of aspartame for humans.

A food safety official for the WHO said that the consumption of aspartame is “not a major concern at the doses which are commonly used.”

The amount of aspartame that was indicated as being potentially harmful would be the equivalent of drinking a dozen or more cans of diet soda every day.

With all this attention focused on aspartame but little in terms of a concrete conclusion, it remains unclear what the WHO sought to achieve by publicizing its risk assessments.

Here’s what to know:

US groups still say it’s safe

The Food and Drug Administration (FDA) publicly split with the WHO’s assessment.

“The FDA disagrees with IARC’s conclusion that these studies support classifying aspartame as a possible carcinogen to humans,” the agency said. “FDA scientists reviewed the scientific information included in IARC’s review in 2021 when it was first made available and identified significant shortcomings in the studies on which IARC relied.”

The food and beverage industry was also quick to issue reassuring statements.

The American Beverage Association on Thursday stated plainly: “Aspartame is safe.”

“People all around the world can be confident in consuming food and beverages with aspartame,” the organization added. “The safety of our products is the highest priority for our industry.”

WHO report offers little for consumers

Marion Nestle, author and Paulette Goddard professor of nutrition, food studies and public health emerita at New York University, took issue with how the WHO reports were released.

“So, the IARC came out and said based on limited evidence, aspartame is possibly a carcinogen. What on Earth are you supposed to do with that?” Nestle asked. “IARC says that there’s tons of evidence that aspartame induces metabolic problems. But I don’t see the evidence, because they haven’t published it.”

As Nestle noted, aspartame has been at the center of controversy for decades.

The sweetener was first approved by the FDA for use in some foods and beverages in 1974 before its approval was suspended due to objections and conflicting studies. Aspartame ultimately entered the U.S. market in 1981.

Why we still don’t know for sure

Despite frustration with the vague, diverging report on aspartame’s safety, health experts acknowledge the difficulty in conducting a thorough study of the additive.

“People use aspartame in very, very small quantities. And they eat lots of other things and behave in lots of other ways. So, it’s very hard to parse out,” said Nestle, who is not associated with the multinational food conglomerate of the same name. “You can’t do the kind of science that you’d want to do, which is to put one group of people on aspartame and the other group without and follow them for 30 or 40 years. But you can’t do that, so everything is inferential.”

Allison Sylvetsky, associate professor of exercise and nutrition sciences at the George Washington University Milken Institute School of Public Health, noted that many studies looking into aspartame also include a variety of other artificial sweeteners, making it difficult to pin down the potential effects of just aspartame.

Why the renewed attention

Even after decades of studies and availability on the market, there is still no broad consensus on aspartame. But the increasing amount of research into the additive and its expanded use in food products likely played a part in the WHO’s focus.

“There’s just more use of these sweeteners. There’s more consumption of these sweeteners, and that’s part of why it’s kind of resurfaced as an important issue,” Sylvetsky said, noting the growth in global efforts to cut down on added sugars in food that has coincided with the ubiquity of artificial sweeteners.

Nestle noted that the sweeteners are “increasingly used for products aimed at children.”

“So, there’s increasing concern about what they do, particularly to kids,” she said.

What the experts say

In light of all this attention and concern over the artificial food additive, the long-held advice remains the same in the end: moderation.

“Foods and beverages that are usually ultra-processed, that contain low-calorie sweeteners, you know, are not desirable in excess,” Sylvetsky said.

Nestle, who personally does not consume products with aspartame because of the taste and the complicated science surrounding it, advised that people should generally try to limit sweetened drinks to “only once in a while and in very small amounts.”

“But I have been accused of being totally out of touch with reality,” she added with a laugh. “I won’t argue that.”