The results, made public on Friday, highlight "limited evidence" for its carcinogenicity in humans. As a result, IARC has classified aspartame as "possibly carcinogenic to humans" (Group 2B), while JECFA reaffirmed the acceptable daily intake of 40 mg/kg body weight.

Aspartame, an artificial sweetener widely used since the 1980s in various food and beverage products, including diet drinks, chewing gum, ice cream, yogurt, breakfast cereal, toothpaste, and medications, has raised concerns regarding its potential health effects.

Dr. Francesco Branca, Director of the Department of Nutrition and Food Safety at WHO, expressed the importance of assessing possible factors contributing to cancer. He stated, "The assessments of aspartame have indicated that, while safety is not a major concern at commonly used doses, potential effects have been described that need to be investigated by more and better studies."

Both IARC and JECFA conducted independent reviews to evaluate the potential carcinogenic hazard and other health risks associated with aspartame consumption. It was the first time IARC assessed aspartame, while JECFA has done so twice before.

Based on the available scientific literature, both assessments acknowledged limitations in the evidence regarding cancer and other health effects. IARC classified aspartame as "possibly carcinogenic to humans" (Group 2B) due to limited evidence of cancer in humans (specifically hepatocellular carcinoma, a type of liver cancer), limited evidence in experimental animals, and limited evidence related to potential cancer-causing mechanisms.

JECFA, on the other hand, concluded that the data evaluated did not provide sufficient reason to alter the established acceptable daily intake (ADI) of 0–40 mg/kg body weight for aspartame. The committee reaffirmed its stance that consuming within this limit is safe. For instance, an adult weighing 70kg would need to consume more than 9–14 cans of diet soft drink containing 200 or 300 mg of aspartame per day to exceed the acceptable daily intake, assuming no other sources of intake from food.

It is important to note that IARC's hazard identifications focus on understanding the carcinogenicity of a substance and do not directly assess the risk of developing cancer at specific exposure levels. IARC classifications reflect the strength of scientific evidence regarding the potential of a substance to cause cancer in humans. The Group 2B classification represents limited evidence for cancer in humans or convincing evidence in experimental animals but not both.

Dr. Mary Schubauer-Berigan of the IARC Monographs program emphasized the need for further research to better understand whether aspartame consumption poses a carcinogenic hazard. She stated, "The findings of limited evidence of carcinogenicity in humans and animals, and of limited mechanistic evidence on how carcinogenicity may occur, underscore the need for more research."

JECFA, responsible for risk assessments, considered the evidence of cancer risk in both animal and human studies. They concluded that the evidence of an association between aspartame consumption and cancer in humans is not convincing. Dr. Moez Sanaa, Head of the Standards and Scientific Advice on Food and Nutrition Unit at WHO, highlighted the necessity for more comprehensive studies, including long-term follow-up and repeated dietary questionnaires, as well as randomized controlled trials to explore mechanistic pathways relevant to insulin regulation, metabolic syndrome, diabetes, and carcinogenicity.

Both IARC and JECFA based their evaluations on scientific data from various sources, including peer-reviewed papers, governmental reports, and studies conducted for regulatory purposes. Independent experts reviewed the studies, and the committees took measures to ensure the independence and reliability of their evaluations.

Moving forward, IARC and WHO will continue to monitor new evidence and encourage independent research groups to conduct further studies on the potential association between aspartame exposure and consumer health effects. underscore the need for more research to refine our understanding on whether consumption of aspartame poses a carcinogenic hazard,” said Dr Mary Schubauer-Berigan of the IARC Monographs programme.

JECFA’s risk assessments determine the probability of a specific type of harm, i.e. cancer, to occur under certain conditions and levels of exposure. It is not unusual for JECFA to factor IARC classifications into its deliberations.

“JECFA also considered the evidence on cancer risk, in animal and human studies, and concluded that the evidence of an association between aspartame consumption and cancer in humans is not convincing,” said Dr Moez Sanaa, WHO’s Head of the Standards and Scientific Advice on Food and Nutrition Unit. “We need better studies with longer follow-up and repeated dietary questionnaires in existing cohorts. We need randomized controlled trials, including studies of mechanistic pathways relevant to insulin regulation, metabolic syndrome and diabetes, particularly as related to carcinogenicity.”

The IARC and JECFA evaluations of the impact of aspartame were based on scientific data collected from a range of sources, including peer-reviewed papers, governmental reports and studies conducted for regulatory purposes. The studies have been reviewed by independent experts, and both committees have taken steps to ensure the independence and reliability of their evaluations.

IARC and WHO will continue to monitor new evidence and encourage independent research groups to develop further studies on the potential association between aspartame exposure and consumer health effects. (ILKHA)