# Aspartame

Aspartame is the methyl ester of the dipeptide aspartyl-phenylalanine, coded E 951 in the EU. It is roughly 200 times sweeter than table sugar. Gram for gram it yields 4 kcal, like protein, but the quantities used are so small that its energy contribution is negligible. Digestion splits it into aspartic acid, phenylalanine, and methanol.

EFSA re-evaluated aspartame in 2013 and set the ADI at 40 mg per kilogram of body weight per day. The FDA uses 50 mg/kg. On 14 July 2023 two WHO bodies reported on the same day. IARC classified aspartame as possibly carcinogenic to humans, group 2B, on limited evidence for hepatocellular carcinoma from three cohort studies. JECFA reviewed the same material and reaffirmed the ADI of 0 to 40 mg/kg.

Group 2B describes how strong the evidence is, not how large any risk would be. It means a link cannot be ruled out, not that one has been established.

The observational signal comes mainly from cohorts such as NutriNet-Santé, where confounding by overall diet and body weight is hard to remove. Randomised trials are short and measure metabolic markers, not cancer. EU labels must declare a source of phenylalanine, because people with phenylketonuria cannot clear it.

## Sources

- Riboli E, Beland FA, Lachenmeier DW, et al.. (2023). Carcinogenicity of aspartame, methyleugenol, and isoeugenol. The Lancet Oncology. https://doi.org/10.1016/S1470-2045(23)00341-8
- EFSA Panel on Food Additives and Nutrient Sources added to Food (ANS). (2013). Scientific Opinion on the re-evaluation of aspartame (E 951) as a food additive. EFSA Journal. https://doi.org/10.2903/j.efsa.2013.3496
- Debras C, Chazelas E, Srour B, et al.. (2022). Artificial sweeteners and cancer risk: Results from the NutriNet-Santé population-based cohort study. PLOS Medicine. https://doi.org/10.1371/journal.pmed.1003950
- World Health Organization, IARC, JECFA. (2023). Aspartame hazard and risk assessment results released. World Health Organization. https://www.who.int/news/item/14-07-2023-aspartame-hazard-and-risk-assessment-results-released

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