Does aspartame cause cancer?
Written by AI from saved sources. A script checks every quote word for word, and a second AI compares each claim with its source. How we work and corrections
These sources do not establish that aspartame causes cancer in people, though some studies found cancer links. The International Agency for Research on Cancer (IARC) classified it as possibly carcinogenic, meaning possibly able to cause cancer. That leaves uncertainty, rather than proof of either harm or zero risk.
Checked against: IARC, JECFA, European Food Safety Authority, October 2026.
What the messages say
IARC classified aspartame as possibly carcinogenic, and NutriNet-Santé reported higher cancer risks among higher aspartame consumers than non-consumers. Taking that seriously is reasonable. The messages also differ. The US Food and Drug Administration (FDA) disputes IARC’s reading of the studies. FDA acknowledges that differing messages from health organisations are hard to follow.
“Studies linked it to liver cancer”
Three studies covering four groups of people informed IARC’s classification. They used artificially sweetened drinks as a stand-in for aspartame intake, rather than measuring aspartame directly. The findings varied:
- The European EPIC study linked drinking more artificially sweetened soft drinks to higher hepatocellular carcinoma risk. This is a type of liver cancer.
- A combined US analysis found that greater consumption of artificially sweetened drinks was associated with higher liver-cancer risk among people with diabetes during the first 12 years of follow-up. It found no statistical evidence of a link among people without diabetes. After 12 years of follow-up, the analysis found no statistical association.
- The CPS-II study found no overall statistical association between artificially sweetened drink intake and deaths from two cancers. These were liver cancer and cancer of bile ducts inside the liver.
WHO and IARC said chance, bias (distortions in the results) or other differences between people could explain the positive findings. Some measurement limitations could also weaken an association. IARC noted that EPIC used a single measurement of drinks taken at the start. This could make a real link look weaker.
“People consuming it got more cancer”
The 2022 NutriNet-Santé study followed 102,865 adults and used repeated food records, including brand names. Compared with non-consumers, participants in the higher aspartame intake group had a higher estimated risk of cancer overall, and women in that group had a higher estimated breast-cancer risk. All participants’ aspartame intakes were below the acceptable daily intake of 40 milligrams per kilogram of body weight per day.
Those findings deserve attention, but the authors said their study could not establish cause and effect. They flagged possible differences they had not accounted for. They also flagged the possibility that health changes influenced what people consumed. Too few cases were available to examine liver cancer separately.
“Animal and lab tests prove it”
Three animal studies found more tumours in mice and rats. IARC judged this evidence limited because of concerns about how the studies were designed, interpreted and reported. Tests of possible ways aspartame could cause cancer also provided limited evidence, from experimental systems.
Thinking tool: hazard versus risk
A hazard assessment asks whether something can cause harm. A risk assessment asks how likely harm is at a given amount. IARC’s aspartame category describes how strong the evidence is, rather than your cancer risk at a particular amount. JECFA assesses how likely harm is under particular conditions and at particular amounts consumed. FDA also disagrees with how IARC interprets the evidence itself.
For other claims, ask how strong the evidence of harm is. Also ask what amount the risk assessment concerns.
Official positions, with dates
- IARC, 14 July 2023: possibly carcinogenic, Group 2B, based on limited human evidence concerning a type of liver cancer.
- JECFA, 14 July 2023: retained its acceptable daily intake of 0–40 milligrams per kilogram of body weight.
- European Food Safety Authority (EFSA), 10 December 2013: safe at then-current exposure levels. On 10 September 2026, while reviewing aspartame–acesulfame salt, EFSA reconfirmed aspartame’s daily limit of 40 milligrams per kilogram of body weight.
- FDA, page current 27 February 2025: no safety concerns under approved conditions of use.
What people also ask
Should I stop drinking aspartame?
JECFA says consumption within its daily limit is safe. FDA gives a separate exception: people with the inherited condition phenylketonuria (PKU) should avoid or restrict aspartame.
Is it bad to drink aspartame every day?
FDA defines aspartame’s acceptable daily intake as an amount considered safe each day over a lifetime. That assessment concerns amount and duration. It is not a rule that any daily consumption is harmful.
How much aspartame is safe to drink per day?
WHO illustrates its limit with a 70-kilogram adult. Exceeding it would take more than 9–14 cans of diet soft drink daily. This assumes 200 or 300 milligrams of aspartame per can and no other aspartame intake. This illustrates exceeding the limit; it is not a drinking recommendation.
What organ does aspartame affect?
For the cancer question, IARC’s classification concerned limited evidence about hepatocellular carcinoma, a type of liver cancer. That does not establish that aspartame causes liver cancer. Chance, bias or other differences could explain the findings.
Check it yourself (5 minutes)
- Open WHO’s “Aspartame hazard and risk assessment results released”, dated 14 July 2023.
- Use your browser’s Find for “IARC classifications”.
- Does the category describe evidence strength or your risk at a given exposure?
What you should have found
“IARC classifications reflect the strength of scientific evidence as to whether an agent can cause cancer in humans, but they do not reflect the risk of developing cancer at a given exposure level.”
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