The Next Time You Reach for That Diet Soda...

By: Michelle Shakib  |  January 2, 2017


The popular low-calorie sweetener aspartame is found almost everywhere. One can find it in every grocery store and most coffee shops and cafes. It is a popular sugar substitute for those looking to keep their daily caloric intake at a minimum. While the taste of sugar combined with zero calories seems like the best of both worlds, there are significant genotoxic risks associated with this dipeptide derivative.


Aspartame itself is not particularly dangerous; the major risks result from the products of the metabolic breakdown of aspartame. The derivatives which pose the most significant risk to consumers are methanol, diketopiperazine, phenylalanine and aspartic acid. The toxicity of these products begins when they enter the bloodstream. Aspartame is first hydrolyzed in the liver, releasing methanol, which is then converted to formaldehyde. The formaldehyde then further oxidizes to form formic acid and carbon dioxide. Formaldehyde itself has several toxic effects on the human body. One such effect includes the disorder metabolic acidosis (elevated acid concentration) which disrupts normal gastrointestinal function. Vision disorders are also caused by formaldehyde, as well as by its oxidized form, formic acid. These toxins destroy the ocular nerves and can induce blindness. Another aspartame byproduct, the amino acid phenylalanine, is a neurotoxin. Elevated phenylalanine levels blocks the transport of critical amino acids to the brain. High levels of phenylalanine can cause seizures and potentially mental retardation as well. Lastly, aspartic acid is also considered a toxin and can destroy astrocytes (neuronal support cells) and neurons at high concentrations.


Aspartame has also been associated with an increased risk of cancer. Various hypotheses state that aspartame consumption leads to a higher risk of mammary cancer, leukemia and lymphoma. In one study, a carcinogenicity bioassay on aspartame was performed on mice. The study included 6 groups of 62 male and female mice who were fed either 32,000, 16,000, 8,000, 2,000 or 0 ppm doses of aspartame from the prenatal stage until death. After the mice died, various examinations were done of their tissues, organs and pathologic lesions. The findings showed that the mice that consumed aspartame had higher incidences of malignant tumor formation. The higher the dose consumed, the more likely both male and female mice were to develop lymphomas. One theory suggests that the higher incidences of cancer can be attributed to the formaldehyde released by aspartame metabolism because formaldehyde is a known carcinogen. Others believe that aspartic acid may also contribute to aspartame’s carcinogenicity since it is often linked to the development of cancerous neoplastic lesions, which are lesions related to abnormal cell growth.

The available research demonstrates that there are many carcinogenic and genotoxic risks associated with the consumption of aspartame. Despite all these risks, aspartame is still ubiquitous in the lives of most Americans. Thankfully, many consumers and food producers are becoming more aware of the dangers, leading to the development of healthier substitutes for low-calorie sweeteners for your coffee and diet soda.