Health effects of aspartame draw new scrutiny from WHO experts

By Giri Viswanathan and Jamie Gumbrecht, CNN
Thu June 29, 2023

The FDA calls aspartame “one of the most studied food additives in the human food supply.”Peter Dazeley/The Image Bank RF/Getty Images
CNN —

Decades after aspartame was approved for use in the United States, the sweetener’s safety is getting another look by global health bodies assessing its potential links to cancer.

The World Health Organization’s International Agency for Research on Cancer analyzed the potential carcinogenic effects of the sweetener this month. A separate WHO and United Nations committee, the Joint Expert Committee on Food Additives, is now updating its risk assessment, including what it considers to be an acceptable daily intake. Their findings have not been made public; they will be released together July 14.

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Aspartame is a common sweetener used in beverages like Coke Zero Sugar, Diet Coke, Sprite Zero, Pepsi Zero Sugar and Mountain Dew Zero Sugar. It’s also found in chewing gum, cough drops and even some toothpastes, among other products. The sweetener has been reviewed multiple times by the US Food and Drug Administration, which says aspartame is safe for the general population.

The FDA updated its website on aspartame and other sweeteners ahead of the WHO analysis; it says it monitors the latest science and levels of consumer exposure to sweeteners and calls aspartame “one of the most studied food additives in the human food supply.”

Both WHO committees are made up of independent health experts from around the world. The International Agency for Research on Cancer looked at existing research to assess whether aspartame is hazardous, and the report from the Joint Expert Committee on Food Additives will provide recommendations for how much aspartame a person can safely consume.

The cancer research committee’s range of carcinogens is broad, according to Qi Sun, an associate professor of nutrition and epidemiology at Harvard’s T.H. Chan School of Public Health. For example, it considers mobile devices “possible carcinogens,” he said, a classification that indicates that a product has “limited” links to cancer in humans.

But Sun says consumers don’t necessarily need to be worried. Whether aspartame can be considered a carcinogen “boils down to what kind of evidence we have,” he said.

“I feel the evidence is pretty sparse to say either way to say ‘aspartame is cancerous’ or to suggest that aspartame is not as carcinogenic,” he said.

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“I think you just have to be aware that there’s a question over this,” James Farrell, a gastrointestinal oncologist at the Yale School of Medicine, said of aspartame’s safety. “And the people who’ve raised this question have an objective reason for raising this question. They’ve looked at it from a medical and scientific perspective … so I think it would be foolish to ignore.”

US health officials raised concerns about WHO having two separate reviews long before the meetings this month.

In a letter in August, the US Department of Health and Human Services said WHO’s simultaneous reviews of aspartame could potentially draw conflicting determinations that would “seriously undermine” confidence in the scientific process and “inflame the current climate of public skepticism about the validity of science and scientific process.”

HHS argued in its letter that the Joint Expert Committee on Food Additives should be the sole reviewer of cancer risk of aspartame in food.

In response, WHO said the groups’ reviews would be complementary. The cancer research committee, which has not previously analyzed aspartame, would assess its potential cancer hazard. The food additive committee would update its risk assessment, including what it considers to be acceptable daily intake of aspartame. The first group’s conclusion “represents only part” of the second group’s assessment, WHO said.

Both letters were posted online by the FDA.

The WHO committees are international bodies, but the FDA will make its own decision on aspartame guidelines. After the reports’ release in July, the agency will probably consider the evidence, Sun said, but is under “no obligation” to change its current regulations.

The American Beverage Association – a group that represents beverage makers such as Coca-Cola and PepsiCo – said in a statement Thursday that safety is a priority.

“The fact that food safety agencies worldwide, including the FDA, continue to find aspartame safe makes us confident in the safety of our products,” it said.

Last month, WHO said people should not use sugar substitutes to lose weight, saying they might have a short-term impact but don’t lead to sustained reduction in obesity.

“Like anything in life, you’ve got to start with everything in moderation,” Farrell said. “If they release data that suggests or questions the safety of [aspartame] … if you’re able to limit your intake, why wouldn’t that be a reasonable thing to think about?”

In Sun’s perspective, artificial sweeteners like aspartame can temporarily be a good choice for people trying to reduce their sugar intake. In the long run, he said, there are much better options for beverage consumption, including water, unsweetened teas or reduced-fat milk, whose health benefits are supported by ample research.

“I think consumers could easily switch to those household beverages to improve their health rather than get concerned about consuming artificially sweetened beverages and cancer,” Sun said. “We don’t have evidence either way.”