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Food additive · Sweetener

Aspartame

E-number
E951
CAS
22839-47-0

A high-intensity sweetener about 200 times sweeter than sugar, used in diet sodas, sugar-free gum and tabletop packets.

  • Food additive
  • Non-nutritive sweetener
  • Ultra-processing marker
  • Expert review pending
High concern Level 3 of 4 How concern levels work

A regulatory warning or restriction somewhere, or strong evidence of harm at typical intake. The concern level sets how many points aspartame costs on a product’s receipt.

What the evidence says

  • Phenylalanine sourceRegulatory

    Labels must warn people with phenylketonuria (PKU) because aspartame contains phenylalanine (US and EU). [1][2]

  • IARC Group 2B (possibly carcinogenic)Strong evidence

    IARC (2023) classified aspartame as Group 2B on limited evidence; JECFA kept the acceptable daily intake at 40 mg/kg body weight, and the FDA disagrees with IARC's classification. [3][4][5][6]

  • Heart or metabolic health (emerging)Emerging evidence

    In the NutriNet-Santé cohort, aspartame intake was associated with higher cancer risk; cause and effect is not established. [7]

  • Heart or metabolic health (emerging)Emerging evidence

    WHO (2023) recommends against using non-sugar sweeteners to control body weight (conditional recommendation); US dietary guidelines advise limiting them. [8][9]

Evidence tiers say how sure the evidence is, separately from how much it matters. About evidence tiers.

Rules around the world

WhereStatusDetailsDateSource
United States Warning label required Permitted; labels must carry "PHENYLKETONURICS: CONTAINS PHENYLALANINE" (21 CFR 172.804). — [1]
European Union Warning label required Permitted (E 951); labels must state it contains a source of phenylalanine. — [2]
Canada Permitted On Health Canada's List of Permitted Sweeteners. — [10]

“Banned” means explicitly prohibited or withdrawn after review; “not permitted” means never authorized there. We use each regulator’s own words.

Popular products that list aspartame

144 of the 17,000 most-scanned products in the US with a GoodSwap page list aspartame. The 12 most scanned:

Diets and allergens

Vegan
Yes
Vegetarian
Yes
Gluten-free
Yes

For the ingredient in general. Always check the package: a product’s own labels win.

Names GoodSwap recognizes on labels (16)
  • e951
  • aspartame
  • nutrasweet
  • equal sweetener
  • aspartame sweetener
  • sweetener aspartame
  • aspartame edulcorant
  • sweeteners aspartame
  • aspartame and acesulfame k
  • aspartame acesulfame potassium
  • aspartame contains phenylalanine
  • aspartame and acesulfame potassium
  • aspartame a source of phenylalanine
  • aspartame and acesulfame k sweeteners
  • aspartame phenylketonurics contains phenylalanine
  • sweetener aspartame contains a source of phenylalanine

Sources

  1. 21 CFR 172.804 Aspartame

    Electronic Code of Federal Regulations (eCFR), U.S. Office of the Federal Register · Mar 24, 2023 · Law

    “PHENYLKETONURICS: CONTAINS PHENYLALANINE”

    ecfr.gov

  2. Regulation (EU) No 1169/2011, Annex III point 2.3 (aspartame)

    European Union (Official Journal) · Oct 25, 2011 · Law

    “‘contains a source of phenylalanine’ shall appear on the label in cases where aspartame/aspartame-acesulfame salt is designated in the list of ingredients by its specific name.”

    eur-lex.europa.eu

  3. Aspartame hazard and risk assessment results released (IARC, WHO and FAO joint news release)

    World Health Organization · Jul 14, 2023 · Agency assessment

    “Citing “limited evidence” for carcinogenicity in humans, IARC classified aspartame as possibly carcinogenic to humans (IARC Group 2B) and JECFA reaffirmed the acceptable daily intake of 40 mg/kg body weight.”

    who.int

  4. Carcinogenicity of aspartame, methyleugenol, and isoeugenol (IARC Monographs Vol. 134 working group summary)

    The Lancet Oncology · August 2023 · IARC

    doi.org

  5. Aspartame and Other Sweeteners in Food

    U.S. Food and Drug Administration · Feb 27, 2025 · Regulator

    “The FDA disagrees with IARC’s conclusion that these studies support classifying aspartame as a possible carcinogen to humans.”

    fda.gov

  6. EFSA completes full risk assessment on aspartame and concludes it is safe at current levels of exposure

    European Food Safety Authority · Dec 10, 2013 · Agency assessment

    “Aspartame and its breakdown products are safe for human consumption at current levels of exposure”

    efsa.europa.eu

  7. Artificial sweeteners and cancer risk: Results from the NutriNet-Santé population-based cohort study

    PLOS Medicine · Mar 24, 2022 · Peer-reviewed

    “In this large cohort study, artificial sweeteners (especially aspartame and acesulfame-K), which are used in many food and beverage brands worldwide, were associated with increased cancer risk.”

    doi.org

  8. WHO advises not to use non-sugar sweeteners for weight control in newly released guideline

    World Health Organization · May 15, 2023 · Agency assessment

    “The recommendation is based on the findings of a systematic review of the available evidence which suggests that use of NSS does not confer any long-term benefit in reducing body fat in adults or children.”

    who.int

  9. Dietary Guidelines for Americans, 2025–2030

    U.S. Department of Health and Human Services and U.S. Department of Agriculture · January 2026 · Regulator

    “Limit foods and beverages that include artificial flavors, petroleum-based dyes, artificial preservatives, and low-calorie non-nutritive sweeteners.”

    cdn.realfood.gov

  10. 9. List of Permitted Sweeteners (Lists of Permitted Food Additives)

    Health Canada · Feb 25, 2025 · Regulator

    “A.3 Aspartame n/a (a) Breakfast cereals (a) Sweetener (a) 5,000 ppm n/a”

    canada.ca