EWG’s recommendation
Avoid or limit food and beverages containing aspartame.
Aspartame has been classified as a possible carcinogen by the World Health Organization’s cancer research agency. Laboratory studies suggest that aspartame and its breakdown products may promote oxidative stress – a process during which reactive molecules damage cells – and may also affect neurological function.
What is aspartame?
Aspartame is a low-calorie artificial sweetener about 200 times sweeter than sugar. It is widely used as a dietary sugar substitute in packaged foods and beverages.
Which foods contain aspartame?
Aspartame is commonly added to diet beverages, powdered drinks and sugar-free chewing gums, as well as a wide range of other reduced-calorie or “light” food products.
Look for aspartame in product ingredient lists, usually below or next to the Nutrition Facts panel, on the back of the package.
How is aspartame regulated?
The Food and Drug Administration is responsible for overseeing food additives and other ingredients. Aspartame is approved for use in food, with an established Acceptable Daily Intake, or ADI, of 50 mg/kg body weight per day in the U.S. Because aspartame is not heat stable, the FDA requires sugar substitutes that contain it to state it is not for use in cooking or baking.
In 2023, the International Agency for Research on Cancer classified aspartame as possibly carcinogenic to humans, based on limited evidence of an association with hepatocellular carcinoma, a type of liver cancer.
The European Food Safety Authority, or EFSA, last evaluated aspartame in 2013 and set an ADI of 40 mg/kg body weight per day. As of February 2026, the safety authority is re-evaluating aspartame-acesulfame K, a sweetener blend that combines aspartame with acesulfame potassium.
Aspartame is prohibited in food certified under Agriculture Department organic standards, which bar synthetic substances.
What does the science say about aspartame?
Laboratory studies have identified several ways aspartame could damage the nervous system through its byproducts.
When aspartame is digested, it breaks down into three components. These byproducts have been shown to increase the production of reactive oxygen species, which can contribute to oxidative stress and damage cells and DNA.
Phenylalanine, one byproduct of aspartame, may alter the production of serotonin and other neurotransmitters. Aspartic acid, another, may overstimulate neurons at high concentrations, eventually leading to cell death and inflammation in the nervous system.
People who can’t process the amino acid phenylalanine should avoid aspartame entirely. The FDA requires any food containing aspartame to carry the label “Phenylketonurics: Contains Phenylalanine.”
A 2025 systematic review of human studies reported associations with increased rates of clinical depression, irritability and spatial disorientation even with aspartame intake below the ADI, and greater vulnerability in people with preexisting cognitive or metabolic conditions.
The WHO advises against the use of non-sugar sweeteners like aspartame for weight control since evidence from research finds that they do not work long-term for weight loss. In fact, studies have reported associations with a higher risk of Type 2 diabetes and cardiovascular disease with higher consumption of non-sugar sweeteners.
Evidence on cancer risk remains mixed. A large French cohort study found an association between aspartame consumption and breast- and obesity-related cancers.
But comprehensive safety reviews by the EFSA and the National Toxicology Program, the U.S. agency that oversees toxicology studies, concluded the evidence does not demonstrate a consistent cancer-causing effect at current levels of dietary exposure. Research in this area remains ongoing.
Find out more
Learn more about recommendations relating to aspartame – and the full EWG Dirty Dozen™ list of food chemicals – on EWG’s research page.
EWG’s Food Scores provides ratings for more than 150,000 foods and drinks based on nutrition, ingredients and processing concerns, and flags unhealthy ultra-processed foods to help you identify alternatives.
EWG’s free, searchable Skin Deep® cosmetic database helps to identify harmful chemicals in personal care and beauty products. EWG Verified® products meet the strictest criteria for transparency and health.
And the Healthy Living app lets you take these tools with you on the go.
