E-Numbers and Food Additive Identification
Many consumers encounter the E-number system on food labels, which can sometimes be confusing. An E-number is a code for substances used as food additives in the European Union and other parts of the world. This standardized numbering system simplifies labeling and identifies specific additives that have been approved as safe for consumption. In this system, E 951 is the designated code for aspartame. Therefore, seeing "sweetener 951" on a product's ingredient list is a direct confirmation that the product contains aspartame.
The Chemical Composition of Aspartame (E 951)
Aspartame is a low-calorie, artificial sweetener that is not a carbohydrate but is made from two naturally occurring amino acids: L-aspartic acid and L-phenylalanine. These are the same amino acids that serve as the building blocks of proteins found in everyday foods like meat, milk, and eggs. Aspartame's sweet taste is achieved when these two amino acids are joined together in a specific way during a chemical process. Once ingested, the body metabolizes aspartame into its constituent parts: aspartic acid, phenylalanine, and a small amount of methanol. Because of its composition, foods containing aspartame must carry a warning for individuals with the rare genetic disorder phenylketonuria (PKU), who cannot metabolize phenylalanine effectively.
Where You Can Find Aspartame
Aspartame is used in a wide variety of food and beverage products, primarily those marketed as sugar-free or low-calorie. Its high intensity of sweetness means that only small amounts are needed, keeping the calorie count negligible. It is often sold as a tabletop sweetener under popular brand names such as NutraSweet®, Equal®, and Sugar Twin®. Aspartame is used in diet and zero-sugar sodas like Diet Coke and Pepsi Max, sugar-free chewing gum (e.g., Trident), light yogurts, sugar-free gelatin mixes (e.g., Jell-O), beverage powders (e.g., Crystal Light), reduced-sugar sauces, and some chewable vitamins and cough drops. It is not heat-stable and loses sweetness when heated, so it's generally avoided in baked goods.
The Ongoing Safety Discussion Around Aspartame
The safety of aspartame has been extensively reviewed over decades by leading health authorities around the world, consistently confirming its safety for consumption within acceptable daily intake (ADI) levels. However, in 2023, the International Agency for Research on Cancer (IARC) classified aspartame as "possibly carcinogenic to humans" (Group 2B) based on limited evidence. This was a hazard identification, distinct from the risk assessment performed by the Joint FAO/WHO Expert Committee on Food Additives (JECFA). JECFA reaffirmed the ADI of 40 mg/kg of body weight per day, stating evidence linking aspartame consumption and cancer was unconvincing. This highlights the difference between identifying a potential hazard and assessing the actual risk under typical exposure.
Comparison: Aspartame (E 951) vs. Sucralose (E 955)
| Feature | Aspartame (E 951) | Sucralose (E 955) |
|---|---|---|
| Composition | Dipeptide from aspartic acid and phenylalanine | Chlorinated sucrose derivative (not a peptide) |
| Sweetness | ~200 times sweeter than sugar | ~600 times sweeter than sugar |
| Heat Stability | Not heat-stable, loses sweetness when heated | Heat-stable, suitable for baking |
| Brand Names | NutraSweet®, Equal®, Sugar Twin® | Splenda® |
| Usage | Diet sodas, chewing gum, yogurt, cold drinks | General purpose, baked goods, beverages, dairy |
A Complex Conclusion
For most people, the question of whether sweetener 951 is the same as aspartame is a simple one with a straightforward answer: yes, they are one and the same. The real complexity lies in the broader conversation surrounding its safety and role in a balanced diet. While decades of extensive research have supported its safety for the general population within approved limits, as confirmed by regulatory agencies like the FDA and JECFA, the 2023 IARC hazard classification highlights ongoing scientific scrutiny. This underscores the importance of interpreting scientific findings carefully and in context. Ultimately, aspartame remains a viable and regulated tool for sugar reduction for many, but awareness of its composition and the latest scientific evaluations is key for informed consumer choices, especially for those with conditions like PKU. For the most authoritative guidance, consumers should continue to follow the advice of their national food safety regulators and consult with healthcare professionals.
Key Safety Regulatory Bodies
The safety of aspartame has been evaluated by the U.S. Food and Drug Administration (FDA), which has consistently affirmed its safety based on numerous studies. The European Food Safety Authority (EFSA) also concluded its safety within the Acceptable Daily Intake (ADI) after multiple reviews. The Joint FAO/WHO Expert Committee on Food Additives (JECFA) reaffirmed the ADI of 40 mg/kg, finding no convincing evidence of a cancer link at current intake levels. In contrast, the International Agency for Research on Cancer (IARC) classified aspartame as "possibly carcinogenic" (Group 2B) in 2023, based on limited evidence of hazard.
