- Aspartame is a low-calorie artificial sweetener widely used as a sugar substitute in foods and beverages. Chemically, it is a methyl ester of the dipeptide composed of two amino acids: aspartic acid and phenylalanine.
- Aspartame is approximately 200 times sweeter than sucrose (table sugar), which means only a small amount is needed to provide the same level of sweetness, significantly reducing the caloric content of products it is used in. Despite its intense sweetness, aspartame contributes about 4 kcal/g—similar to protein—because it is metabolized like other amino acid compounds, although the amounts used are so small that the calorie contribution is negligible.
- Aspartame is used in a wide range of sugar-free and “diet” products, including soft drinks, chewing gum, yogurt, table-top sweeteners, and desserts. It is especially prevalent in carbonated beverages and is often identified on packaging by its E number (E951 in the EU) or brand names such as Equal, NutraSweet, or Canderel. It is popular among individuals seeking to reduce their sugar intake, including those managing diabetes, obesity, or metabolic syndrome.
- One of the unique features of aspartame is its clean, sugar-like taste without the bitter or metallic aftertaste associated with some other synthetic sweeteners. However, it is not heat-stable, meaning it breaks down at high temperatures and loses its sweetness, making it unsuitable for baking or cooking at high heat. In such cases, more heat-stable sweeteners like sucralose or stevia are preferred.
- Aspartame is metabolized in the body into its components: aspartic acid, phenylalanine, and a small amount of methanol. Although these metabolites occur naturally in many protein-rich foods, individuals with the rare genetic disorder phenylketonuria (PKU) must strictly avoid aspartame due to their inability to properly metabolize phenylalanine, which can lead to serious neurological damage. Consequently, foods containing aspartame are required by law in many countries to carry a warning label for people with PKU.
- The safety of aspartame has been a subject of public concern and scientific investigation for decades. Extensive reviews by major regulatory bodies, including the U.S. Food and Drug Administration (FDA), the European Food Safety Authority (EFSA), the World Health Organization (WHO), and others, have consistently concluded that aspartame is safe for the general population when consumed within established acceptable daily intake (ADI) limits. The ADI for aspartame is typically set at 40 mg/kg body weight per day in the EU and 50 mg/kg in the U.S., which is much higher than typical consumption levels.
- Nonetheless, aspartame has been the focus of ongoing debate and research, particularly around concerns of potential associations with cancer, neurological effects, or behavioral changes. While most high-quality studies have found no consistent evidence of harm at normal consumption levels, a few controversial studies have prompted further scrutiny. For example, in 2023, the WHO’s International Agency for Research on Cancer (IARC) classified aspartame as “possibly carcinogenic to humans” (Group 2B), based on limited evidence, while at the same time, WHO and FAO reaffirmed its safety within existing ADI limits, emphasizing that no immediate change in consumption guidance was needed.
