E951 - Aspartame

At a glance

• Role: Low- and no-calorie sweetener for foods and beverages
• Sweetness: About 200× sweeter than sugar by weight
• Taste: Sugar-like sweetness; often blended with other sweeteners
• Heat: Not ideal for long baking; it can lose sweetness when heated
• Breakdown in the body: Turns into two amino acids (aspartic acid and phenylalanine) and a small amount of methanol
• Safety: Approved by major regulators with defined daily limits
• Special note: People with PKU must avoid it due to phenylalanine

Why is Aspartame added to food?

Manufacturers use aspartame to deliver sweetness with very few calories because it is roughly 200 times sweeter than sucrose (table sugar).¹ This lets foods and drinks taste sweet while keeping total sugars and energy lower.¹

What foods contain Aspartame?

Aspartame shows up widely in “diet” or “zero” soft drinks, sugar-free gum, tabletop sweeteners, flavored waters, powdered drink mixes, reduced-sugar desserts, and some light yogurts and puddings. In the United States, its use as a sweetener is regulated under the Code of Federal Regulations (CFR) and products that contain it must carry the statement “Phenylketonurics: Contains phenylalanine.”²

What can replace Aspartame?

• Other high-intensity sweeteners: acesulfame K, sucralose, saccharin, steviol glycosides, neotame, advantame
• Sugar alcohols (polyols): erythritol, xylitol, sorbitol
• Blends are common to improve taste, reduce aftertaste, or enhance stability.

How is Aspartame made?

Aspartame is the methyl ester of a dipeptide made from two amino acids: L-aspartic acid and L-phenylalanine. Commercially, manufacturers join these building blocks—often via controlled enzymatic or chemical steps—to form L-aspartyl-L-phenylalanine methyl ester, then purify it to food-grade quality.³ Aspartame can lose sweetness when heated or held for long periods in water, so it is used most often in cold or short-shelf-life products.¹

Is Aspartame safe to eat?

Food safety agencies have evaluated aspartame many times. The European Food Safety Authority (EFSA) set an Acceptable Daily Intake (ADI—an estimate of the amount you can consume daily over a lifetime without risk) of 40 mg per kilogram of body weight per day.³ In 2023, the International Agency for Research on Cancer (IARC) classified aspartame as “possibly carcinogenic to humans” (Group 2B), which signals limited evidence and calls for more research, not a change in use rules.⁴ On the same day, the Joint FAO/WHO Expert Committee on Food Additives (JECFA) reaffirmed the ADI of 0–40 mg/kg/day and concluded current intakes are not a safety concern.⁵ The U.S. Food and Drug Administration (FDA) considers aspartame safe and uses an ADI of 50 mg/kg/day.⁶

Does Aspartame have any benefits?

Aspartame provides a sweet taste with very few calories, which helps reduce added sugars and energy in foods and drinks.¹ It is one option that can support lower-sugar eating patterns without giving up sweetness, when used within the ADI.³

Who should avoid Aspartame?

People with phenylketonuria (PKU)—a rare genetic condition that requires strict control of phenylalanine intake—must avoid aspartame because it supplies phenylalanine; U.S. labels must clearly warn “Phenylketonurics: Contains phenylalanine.”² Others who are advised by a clinician to limit phenylalanine should also discuss aspartame with their healthcare provider.³

Myths & facts

• Myth: “Aspartame causes cancer.”
  Fact: IARC labeled it “possibly carcinogenic” (Group 2B) based on limited evidence, while JECFA reviewed the same data and kept the ADI at 0–40 mg/kg/day, concluding it is not a safety concern at current intakes.⁴⁵
• Myth: “Aspartame turns into dangerous chemicals in the body.”
  Fact: Your body breaks aspartame into amino acids (aspartic acid and phenylalanine) and a small amount of methanol; safety evaluations considered these breakdown products and still set ADIs that are protective.³
• Myth: “Regulators say to stop using aspartame.”
  Fact: FDA states aspartame is safe for the general population when used under the approved conditions and within the ADI.⁶
• Myth: “You can cook anything with aspartame.”
  Fact: Aspartame can lose sweetness at high temperatures or over long storage in water, so it is not ideal for baking or simmered sauces.¹

Aspartame in branded foods

Formulas change often, so always read the ingredient list. Look for “aspartame,” “E951,” and the required “Phenylketonurics: Contains phenylalanine” statement on products such as:

• “Diet” or “zero sugar” soft drinks and flavored waters
• Sugar-free chewing gum and mints
• Tabletop sweetener packets and tablets
• Sugar-free or reduced-sugar drink mixes, gelatins, puddings, and light dairy desserts

References

Footnotes

1. High-Intensity Sweeteners — U.S. FDA. https://www.fda.gov/food/food-additives-petitions/high-intensity-sweeteners ↩ ↩² ↩³ ↩⁴ ↩⁵

2. 21 CFR 172.804 Aspartame — U.S. eCFR. https://www.ecfr.gov/current/title-21/chapter-I/subchapter-B/part-172/subpart-D/section-172.804 ↩ ↩²

3. Scientific Opinion on the re-evaluation of aspartame (E 951) as a food additive — EFSA. https://www.efsa.europa.eu/en/efsajournal/pub/3496 ↩ ↩² ↩³ ↩⁴ ↩⁵

4. IARC assesses the carcinogenicity of aspartame — WHO/IARC Press Release 293 (2023). https://www.iarc.who.int/wp-content/uploads/2023/07/PR293_E.pdf ↩ ↩²

5. Summary of the 96th meeting of JECFA: Aspartame evaluation and ADI — WHO/FAO (2023). https://www.who.int/publications/m/item/summary-of-the-96th-meeting-of-the-joint-fao-who-expert-committee-on-food-additives-(jecfa) ↩ ↩²

6. FDA statement on IARC classification and JECFA evaluation of aspartame (2023) — U.S. FDA. https://www.fda.gov/food/food-additives-petitions/fda-statement-iarc-classification-and-jecfa-evaluation-aspartame ↩ ↩²