Written by Erica Gittleson, RD; Select sections of article written by and article reviewed by Dr. Bojana Jankovic Weatherly.

What is aspartame?

Aspartame is an artificial, high-intensity sweetener. It is 200x sweeter than sugar.  

What’s it in?

Aspartame is in sodas like Diet Coke, Coke Zero and Pepsi Zero Sugar, low-calorie coffee sweeteners like Equal and NutraSweet, and some juices. In food, aspartame is often in no-sugar salad dressing, low-calorie ice cream, gelatins and puddings like Jell-O Sugar Free Instant Pudding. It’s also in sugar-free gum like Extra.

What the WHO is saying:

Assessments of the health impacts of aspartame were released by the International Agency for Research on Cancer (IARC) and the World Health Organization (WHO) and the Food and Agriculture Organization (FAO) Joint Expert Committee on Food Additives (JECFA) citing “limited evidence for carcinogenicity in humans”.

What does this mean? 

IARC classified aspartame as possibly carcinogenic to humans and JECFA reaffirmedthe acceptable daily intake of 40mg of aspartame per kg body weight. To put this intoperspective, someone who weighs the American average of 80 kilograms or 176 poundscould drink up to 16 cans of diet soda a day and stay within the limits. E.g., 80kg x40mg/kg = 3200mg; there are 200mg of aspartame in a 12oz diet coke, so that’s3200mg/200mg = 16 diet cokes. To be clear: while this puts the recommendations intoperspective, we are not suggesting anyone should be consuming nearly as much andrecommend avoiding any sugary or diet drinks altogether.

The two bodies conducted independent but complementary reviews to assess the potential carcinogenic hazard/risk. After reviewing the available scientific literature, both evaluations noted limitations in the evidence for cancer and other health effects.

According to IARC’s Dr. Mary Schubauer-Berigan, “The findings of limited evidence ofcarcinogenicity in humans and animals, and of limited mechanistic evidence on howcarcinogenicity may occur, underscore the need for more research to refine ourunderstanding on whether consumption of aspartame poses a carcinogenic hazard.” Dr. Moez Sanaa from WHO’s Head of Standards and Scientific Advice on Food alsostated “We need better studies with longer follow-ups and repeated dietaryquestionnaires in existing cohorts. We also need randomized controlled trials, includingstudies of mechanistic pathways relevant to insulin regulation, metabolic syndrome anddiabetes, particularly as related to carcinogenicity.” IARC and WHO stated they’llcontinue to monitor new evidence and encourage independent research groups todevelop further studies on the potential association between aspartame exposure andconsumer health effects.

So, is diet soda better than regular soda? 

If you comb through Pubmed (database of medical and scientific articles published inpeer-reviewed journals) articles, you will find the same result over and over: both dietand regular soda are harmful and are not recommended. According to research, dietand regular soda consumption are linked to a myriad of diseases and conditions such asobesity, insulin confusion, diabetes, hypertension and heart disease. One study supportsthe contribution of sugar-sweetened beverage consumption in the diabetes epidemic.

However, switching to artificially sweetened diet beverages may not lower the risk of diabetes, as diet soda consumption cannot be ruled out as an independent diabetes risk factor. That said, it’s clear neither is good for us. In conclusion, I’d recommend sticking with water, tea, fruit infused water, seltzer, kombucha, or even coconut water (be mindful of sugar content and portion size).

https://health.clevelandclinic.org/3-reasons-you-should-kick-your-diet-soda-habit/ 
https://pubmed.ncbi.nlm.nih.gov/32529512/ 
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3824455/ 
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5998368/ 
https://www.who.int/news/item/14-07-2023-aspartame-hazard-and-risk-assessment-results-
released 
https://pubmed.ncbi.nlm.nih.gov/32529512/

For more information on the facts about sugar substitutes, see our post Sugar
Substitutes: Which Ones Are Safe and How to Avoid Harmful Ones?