Sorry, Diet Coke addicts. The World Health Organization (WHO) designated aspartame, an artificial sweetener commonly used in diet sodas, as “possibly carcinogenic to humans” on Thursday—despite a conflicting assertion from the U.S. Food and Drug Administration.
The decision comes from a panel of 25 researchers and experts at the WHO’s International Agency for Research on Cancer (IARC) who published their decision in The Lancet Oncology. The committee wrote that the classification was a result of “limited” evidence that aspartame causes cancer in humans along with “sufficient” evidence for cancer in animal models such as mice.
While the decision doesn’t change the WHO’s recommendation for daily intake limit of aspartame, it does classify it as being as carcinogenic as red meat. However, evidence doesn’t conclusively prove that it’s as dangerous as proven cancer-causing substances such as tobacco, asbestos, and greenhouse gasses.
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“The WHO uses that ‘possible’ terminology to indicate agents that have not definitively been linked to cancer development—but there is concerning evidence in animals basically,” Neil M. Iyengar, a medical oncologist and expert on exercise oncology at Memorial Sloan Kettering Cancer Center in New York, told The Daily Beast. “That doesn’t always translate to the same impact in humans.”
However, the WHO’s findings aren’t being taken as a universal consensus: FDA itself released a statement toNPR voicing its disagreement, saying that just because the substance is labeled as potentially carcinogenic “does not mean that aspartame is actually linked to cancer.” This further underscores the murky and controversial nature of the sweetener and whether or not it poses a threat to human health.
What Is Aspartame?
Aspartame is an artificial sweetener that was discovered in 1965 after a chemist named James Schlatter, who was in the process of developing a drug to treat ulcers, licked his finger to turn the page of a book. He immediately tasted an intense sweetness that he later discovered was due to a solution made of aspartic acid and phenylalanine.
The substance is known as a non-nutritive sweetener, which means it doesn’t provide any meaningful nutrition by way of calories to the body. As such, it’s often used in beverages such as diet sodas, juice, flavored water, and also food products such as sugar-free ice cream, chewing gum, and candy.
Aspartame is about 200 times sweeter than regular sugar, which makes it an effective additive to food and drinks for those trying to lose weight or just watch their sugar intake.
Is Aspartame Bad for Me?
There have been a lot of studies into the health effects of artificial sweeteners over the years, with a number showing evidence that aspartame may pose a risk to humans.
In 2006, Italian researchers at the Ramazzini Institute found that aspartame caused increases in malignant tumors in the organs of rats and mice. A follow up study published in Environmental Health in 2021 verified these findings in rodents, adding that “prenatal exposure to aspartame increases cancer risk in rodent offspring.” The authors suggested that food agencies and governing bodies take steps to reexamine and potentially limit exposure to the artificial sweetener in pregnant women.
However, the findings are much murkier when it comes to humans. While there is some evidence to suggest that the substance can be linked to health issues such as cancer, heart disease, and even depression, the research is largely inconclusive and there’s a general lack of scientific consensus when it comes to aspartame.
“Artificial sweeteners have really been under scrutiny in the research world for many years now, because of the concern of how highly processed they are and what that might mean for cancer risk,” Iyengar said. “With aspartame, specifically, the evidence has been really mixed.”
He added that when it comes to large population studies, only a few have “shown a slightly increased cancer risk associated with consumption of significant amounts of aspartame” and that “there have also been several studies that have shown no risk associated with aspartame consumption.”
Iyengar did note that there has been more recent research with regards to aspartame’s impact on human gut microbiome. Since gut bacteria plays a huge role in protecting the body against illnesses including cancer, any changes that might negatively impact it could have a negative effect on the entire body.
“We know that the more diverse a person's gut microbiome is, the lower their risk of developing several cancers,” he said. “Aspartame can lower the diversity of the gut microbiome.”
Should I Avoid Drinking Diet Soda?
That’s the wrong way of looking at it, according to Iyengar. He argues that there are levels of acceptable and unacceptable risk that we should all take into account when it comes to living a healthy lifestyle. For example, if you are already dealing with risk factors such as nicotine addiction, alcoholism, and/or obesity, you should focus primarily on tackling those issues before you need to worry about having a Diet Coke every now and again.
And if food and beverage products that contain aspartame such as sugar free desserts and diet soda helps you cut back on eating and drinking an unhealthy amount of calories, then it far outweighs any risks that you might get from consuming them.
“Lifestyle risk factors like obesity majorly impact cancer risk,” Iyengar explained. “We know from multiple nutrition studies that it's really our overall dietary pattern, rather than reducing it down to singular micronutrients like aspartame, or singular foods that impact our cancer risk.”
He added that if somebody is eating an overall healthy diet, but drinks a diet beverage “here and there” he’s not “particularly worried about that.” The real issue in his view is if people start putting aspartame and diet food and drinks on the same level as bigger risk factors.
“I think a potential negative impact is if it creates more anxiety and people start thinking about it as a risk factor that’s on par with something like obesity,” he says. “I think that’s problematic, because there’s really no comparison. Obesity is a much greater risk factor.”
So if you are generally healthy and are very conscious about what goes into your body, it might be a good idea to cut down or avoid diet sodas and artificial sweeteners the same way you would a juicy steak or cheeseburger. It’s fine every once in a while, but like so many wonderful things in life, it’s better if you just do it in moderation.
