Diet Coke fanatics have been screaming, crying, and throwing up since aspartame, the sweetening agent in the soda, was declared “possibly carcinogenic to humans” last week. The new, worryingly worded designation comes from the International Agency for Research on Cancer (IARC), a part of the World Health Organization responsible for cancer research. The artificial sweetener is used in almost every low- or no-calorie food, such as sugar-free chewing gums, sugar-free Jell-O, and (notoriously) diet sodas. Now consumers, especially those rabid Diet Coke fans, are worried for their health (others have vowed to drink Diet Coke forever). But is aspartame actively dangerous?
This isn’t the first time there’s been a scare around aspartame. As the subject of countless studies, aspartame has been scrutinized by both the public and scientists since it was first synthesized in the mid-1960s. It was approved for use in dry foods by the Food and Drug Administration in 1974. Then that approval was revoked by the FDA in 1980. Then the FDA reinstated the approval in 1981. In fact, according to the FDA, aspartame is one of the most examined food additives on the market.
Yes, aspartame has a sordid past. (Who among us doesn’t?) To understand the enigma that is aspartame, it’s important to understand the twists and turns that regulatory agencies have taken while trying to chase down its health risk. Today, the FDA states on its website that it deems aspartame safe and continues to evaluate new research data around its safety. It is “safe for the general population” when consumed within the FDA’s acceptable daily intake level of 50 milligrams per kilogram of body weight per day.
The short of it: Although the additive may not be downright healthy, chances are it won’t be the cause of your demise.
Aspartame had a shady start
Like many momentous scientific discoveries (penicillin, Botox, pineapple on pizza, probably), aspartame was discovered by accident. As the story goes, James Schlatter synthesized aspartame in a lab in 1965 while researching anti-ulcer drugs. He discovered it was sweet when a drop of it landed on his finger and he licked it off—something I have to imagine they tell you to definitely not do on day one of scientist school. Regardless, Schlatter discovered aspartame was 200 times sweeter than traditional sugar, and thus history was made.
In 1974, aspartame was approved for use as a tabletop sweetener and in chewing gum, breakfast cereals, and dry bases for foods. Things get a little corrupt-seeming and murky from there: As the Huffington Post reveals, after concerns were raised on the initial research behind aspartame safety, three independent scientists on an FDA Board of Inquiry confirmed in 1980 that aspartame “might induce brain tumors,” leading to a nationwide ban for aspartame use. The next year, Donald Rumsfeld, the then CEO of aspartame patent holder G.D. Searle, became part of the transition team to the newly elected President Ronald Reagan.
Under the Reagan administration, Arthur Hull Hayes Jr., MD, a pharmacologist committed to streamlining the FDA’s drug approval process, was immediately named the new FDA commissioner. Then, through a miasma of executive orders, committee packing, and an eventual tiebreaking vote from Hayes, aspartame was approved for use as an artificial sweetener in dry goods. A few years later, in ’83, Hayes stepped down from the FDA after accusations that he accepted money for “speeches to private groups,” though he denied that the allegations were behind his decision. Before he left his post, he approved the use of aspartame in beverages.
Aspartame has been inconclusively linked to lots of issues
Although the FDA deems aspartame one of the most studied food additives, a lot of that research has been fairly inconclusive. A 2021 review by scientists at the Medical University of Lodz discussed 12 behavioral and health outcomes said by researchers in previous studies to be linked to consuming aspartame, including obesity, genotoxicity, and yes, cancer. While there appear to be some links to, say, behavioral changes like depression, most of the results cited in the 2021 review are inconclusive and not definite. That sounds incredibly worrying, but for context, beverages like regular milk have the same potential for such changes.
An analysis from 2017 of 372 studies on various sweeteners lands on similar conclusions: “Overall there is no conclusive evidence for beneficial and harmful effects on [health] outcomes,” including appetite, risk of cancer, diabetes, and weight gain. Issues like (strap in, it’s a long list) headaches, depression, behavioral and cognitive effects, neurological effects, risk of preterm delivery, cardiovascular effects or risk of chronic kidney disease were also discussed. But ultimately, the study concluded that further research was needed.
Two months before aspartame was deemed possibly carcinogenic, WHO also declared that aspartame could increase the risk of type 2 diabetes and cardiovascular diseases. “It’s not surprising to me that the World Health Organization didn’t find really any difference in health benefits between a regular soda and a diet soda,” Stephanie McBurnett, a registered dietitian, said to the Times. “They’re both processed foods.”
So, is it carcinogenic or not?
Yes, the IARC has deemed aspartame “possibly carcinogenic to humans,” but as worrying as that sounds, it’s important to understand how the IARC organizes these substances and behaviors in terms of their cancer-causing potential. Essentially, there are four bureaucratic-sounding categories: carcinogenic to humans, probably carcinogenic to humans, possibly carcinogenic to humans, and not classifiable as to its carcinogenicity to humans. These categories only refer to the level of scientific evidence that the risk of exposure could be carcinogenic—that is to say, stuff that’s probably carcinogenic has more scientific evidence behind it than something that’s possibly carcinogenic.
For instance, the IARC classifies “night shift work” as probably carcinogenic—that is, there is more evidence to support the idea that working an overnight shift is likely carcinogenic than there is evidence for consuming aspartame. Some other things that have been deemed “possibly” carcinogenic in the past: “pickled vegetables (traditional Asian),” ginkgo biloba, working in the textile manufacturing industry, and putting a talc-based body powder on your perineum.
If you’ve been reading all the aspartame news while sipping a Diet Coke, slowly feeling a wave of anxiety grow inside you, let me provide some more context that may put you at ease. The FDA isn’t alone in its approval of aspartame. Although governments abroad recommend a slightly lower level of acceptable daily intake, the UK, Spain, Italy, France, and Australia, among others, have also approved the general use of aspartame.
Despite this new designation, though, a lot of food companies will probably keep using aspartame. It is, after all, cheaper than other sweeteners, and since it’s been in use for such a long time, many businesses have incredibly streamlined aspartame-centric supply lines in place, according to The New York Times. Leaders like Hugh F. Johnston, the chief financial officer of PepsiCo, don’t expect to make changes unless there’s a huge uprising from the company’s consumer base. “I do believe that, in fact, this is not going to be a significant issue with consumers,” he said in an interview with Bloomberg Markets that aired last Thursday, “based on just the preponderance of evidence that suggests aspartame is safe.”
The bottom line: Aspartame’s effect on your health has been a little sketchy since its inception, and it may or may not have been popularized through some shady politicking. But when the WHO calls something possibly cancer-causing, it’s really an incredibly broad designation. According to the WHO’s own guidelines, a 150-pound person would have to drink more than a dozen cans of soda per day to step over the recommended daily intake of aspartame. There’s a chance aspartame isn’t incredible for you in large amounts over a prolonged period, but it probably won’t kill you in the levels you currently consume it, which is hopefully a relief to the aspartame lovers among us. Now, if you’ll excuse me, I have to get back to applying talc-based body powder to my perineum.