Aspartame has been deemed a probable carcinogenic threat to humans by the International Agency for Research on Cancer (IARC), the World Health Organization’s dedicated cancer agency.
The Joint WHO and Food and Agriculture Organization’s Expert Committee on Food Additives examined the risk and made recommendations on how much aspartame is safe to take. They have advised a daily dosage of 0 to 40mg per kilo of body weight, which is what we now have in Australia.

A danger is not the same as a risk. The hazard rating indicates that the agent is capable of causing cancer; the risk rating indicates the possibility that it will cause cancer. Aspartame is a synthetic sweetener that is 200 times sweeter than sugar but contains no calories. It’s found in a range of items, including carbonated drinks like Coke Zero, Diet Coke, Pepsi Max, and several house brands. Look for the ingredient number 951 to identify aspartame in drinks and foods.

Aspartame may also be found in yoghurt and sweets, although because it is unstable at high temperatures, it is not used in baked goods. Equal, Nutrasweet, Canderel, and Sugar Twin are all brand names for aspartame. The permitted daily dose in Australia is 40mg per kilo of body weight per day, which is approximately 60 sachets. The acceptable daily dosage in America has been established at 75 sachets.

IARC examined the global evidence base, including data from observational studies, experimental studies, and animal studies. They discovered some limited evidence in human studies associating aspartame with cancer (particularly, liver cancer), as well as some limited evidence in animal studies.

They also considered biological mechanism studies that demonstrated how aspartame use could lead to cancer. Typically, these are lab-based studies that demonstrate how exposure to the substance might cause cancer. In this case, they discovered that there was little evidence that aspartame could cause cancer. There were only three human studies that investigated cancer and aspartame consumption. These large observational studies used the intake of soft drinks as an indicator of aspartame intake.

All three discovered a link between artificially sweetened beverages and liver cancer in either the entire population or sub-groups within it. However, these investigations were unable to rule out other factors that could have contributed to the findings.

A European study that monitored 475,000 participants for 11 years discovered that each additional serve of diet soft drink taken per week was associated with a 6% increased risk of liver cancer. The investigators did find, however, that due to the rarity of liver cancer, the study had a small number of participants.

In a study from the US, increased risk of liver cancer was seen in people with diabetes who drank more than two or more cans of a diet soda a week. The third study, also from the United States, discovered an increase in the incidence of liver cancer in males who never smoked and consumed two or more artificially sweetened drinks each day.

As a result, they have chosen to classify aspartame as a “possible carcinogen” in Group 2b. However, they have stated that more and better study is required to fully understand the association between aspartame and cancer.

IARC has four categories (groupings) of possible compounds (or, as IARC refers to them, “agents”) that may cause cancer.


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