Limited evidence on whether the artificial sweetener causes cancer in humans, more studies on carcinogenicity needed
Aspartame is a low-calorie artificial sweetener that is approximately 200 times sweeter than sugar. Photo: iStock_ Artificial sweetener aspartame has been labelled “possibly carcinogenic to humans”, according to the International Agency for Research on Cancer (IARC), which is the cancer agency of the World Health Organization (WHO).
This classification, IARC noted, is based on limited evidence on whether aspartame causes cancer in humans, specifically hepatocellular carcinoma (a type of liver cancer). It also called for better studies.
Read more: Artificial sweeteners may be contributing to diabetes epidemic
Aspartame is a low-calorie artificial sweetener that is approximately 200 times sweeter than sugar. It is a white, odourless powder and is used in more than 5,000 food products globally.
Its link with cancer was reported in 2006 and 2007 when scientists from the Ramazzini Institute (RI) found that aspartame causes dose-related increases in malignant tumours in multiple organs in rats and mice. However, other scientists flagged issues with the study.
In 2021, a commentary from journal Environmental Health lent support to the findings from RI, finding that aspartame is a chemical carcinogen in rodents
“Cancer is one of the leading causes of death globally. Every year, 1 in 6 people die from cancer. Science is continuously expanding to assess the possible initiating or facilitating factors of cancer, in the hope of reducing these numbers and the human toll,” said Dr Francesco Branca, director of the Department of Nutrition and Food Safety, WHO.
In June 2023, a Working Group of 25 scientists from 12 countries met at the IARC in Lyon, France, their evaluation of carcinogenicity.
They combed through data collected from peer-reviewed papers, governmental reports and studies conducted for regulatory purposes.
Read more: Lateral Thoughts: Will WHO norms on artificial sweeteners help consumers?
Studies in humans have been limited. Three papers, which assessed the link between aspartame and liver cancer, found a possible link. The ICAR, however, added that chance, bias or confounding could have interfered with the positive findings.
There is also limited evidence for cancer in experimental animals, the ICAR noted. Three studies have recorded increased cancer incidence in mice and rats.
“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 to refine our understanding of whether consumption of aspartame poses a carcinogenic hazard,” Mary Schubauer-Berigan, of the IARC Monographs Programme, said in a statement.
Branca noted that the potential effects mentioned in a few studies need to be investigated by more and better studies.
Also, the Joint Food and Agriculture Organization of the United Nations / WHO Expert Committee on Food Additives, an international scientific expert committee, found no convincing evidence from experimental animal or human data that aspartame has adverse effects after consumption.
JECFA also did not change the acceptable daily intake of aspartame, which was fixed at 40 milligrammes per kilogram body weight.
Read more: Using sugar substitutes to lose weight could cause harm long-term, warns WHO
An adult weighing 70 kilogrammes would need to consume more than 9–14 cans per day to exceed the acceptable daily intake, assuming the person did not consume other intake from other food sources. A can of diet soft drink contains 200-300 milligrammes of aspartame.
“We need better studies with longer follow-up and repeated dietary questionnaires in existing cohorts,” Moez Sanaa, WHO’s Head of the Standards and Scientific Advice on Food and Nutrition Unit, said in a statement.
Randomised controlled trials, including studies of mechanistic pathways relevant to insulin regulation, metabolic syndrome and diabetes, particularly as related to carcinogenicity, are also needed, Sanaa added.
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