Illustration: Natalie Peeples/Axios
Despite Diet Coke's cultish following, sales have been in decline over perceptions of its health risks.
Why it matters: A World Health Organization cancer agency on Thursday classified aspartame — a key sweetener — as possibly carcinogenic, though experts say that likely doesn't mean you need to quit Diet Coke.
Driving the news: Consumer concern about aspartame health warnings has already hurt Diet Coke sales.
- The soda "has been in a long-term decline as loyal consumers age out of the product," Beverage Digest editor and publisher Duane Stanford told Axios.
- Adding flavors and other attempts to recruit younger Diet Coke drinkers have failed.
Between the lines: The WHO's specialized cancer research arm — the International Agency for Research on Cancer (IARC) — issued the new warning on aspartame's risk level, adding it needs further research.
- The IARC now considers aspartame a class 2B carcinogen, "possibly carcinogenic to humans," based on limited evidence, including animal studies.
- Evidence was strongest — though still limited — for liver cancer in humans, said Mary Schubauer-Berigan, IARC classification branch head.
- Other substances in the 2B category include pickled vegetables and aloe vera. (Coffee was, too, before being reduced to 3 in 2016.)
Meanwhile, the FDA said it "disagrees with IARC's conclusion" to classify aspartame as a possible carcinogen to humans.
Of note: The IARC only looks at whether something could cause cancer, not at what dose it's dangerous.
- Another group — the Joint Food and Agriculture Organization/WHO Expert Committee on Food Additives (JECFA) — evaluates how much of an additive can be consumed without major risk.
- JECFA didn't update their recommended daily intake of aspartame with the IARC's findings.
Reality check: A 150-pound person could drink 14 cans of Diet Coke in a day and still be within the JECFA's safe range, according to the math of Professor Tracy Crane, co-leader of the Cancer Control Research Program at Sylvester Comprehensive Cancer Center.
Diet Coke drinkers might not need to kick the can completely — but the new aspartame label could be a moment to assess how much artificial sugar and added sugar is in your diet.
- "Occasional consumption of aspartame is… probably not going to be associated with a health risk for most individuals," said Dr. Francesco Branca, WHO director of nutrition and food safety.
- Kevin Keane, interim CEO of American Beverage, which represents The Coca-Cola Company, told Axios: “Aspartame is safe... This strong conclusion reinforces the position of the FDA and food safety agencies from more than 90 countries.”
By the numbers: The amount of Diet Coke consumed during the first quarter of this year declined 6.5%, compared to a narrower 2.8% decline for the soft drink category, Stanford said.
- And for the 12 months ending in March 2023, more than 1 in 4 adults said they were avoiding artificial sweeteners like aspartame in their diets, per a Circana/Health Attitudes & Behavioral Tracker.
But Diet Coke isn't Diet Coke without aspartame.
- The fizzy, light, distinctively not-Coke flavor is "characterized in large part by aspartame," Stanford said.
Thought bubble: I'm not ready to give up my occasional keep-me-awake Diet Coke, and I have a feeling Tom Hanks isn't, either.
Go deeper: Possible health impacts of artificial sugar
Editor’s note: This story was updated to include a new statement from the FDA.