Put Down that Diet Coke! The Dangers of Aspartame

Lucy Guillory, Editor

Originally published September 2008.

Lucy Guillory
Lucy Guillory

Hello my name is Lucy and I am a Diet Coke-aholic. I drink about five cans a day and go through several twelve packs a week. I’ve been drinking it since high school. My Plan B if graduate school doesn’t work out is to become a taste tester for Coca-Cola.

Until recently, I thought drinking a lot of diet soda was not particularly healthy but not harmful either. However, some studies show that the artificial sweetener in Diet Coke, aspartame, may actually cause a variety of health problems including cancer and neurological diseases.

Aspartame is a nonsaccharide sweetener used in various diet beverages, sugar-free chewing gums, and also as a condiment for coffee. It is marketed under several commercial names including Equal and NutraSweet. Aspartame’s chemical structure is a dipeptide ester of aspartic acid and phenylalanine. During metabolism it is broken down into its amino acid components as well as methanol, formaldehyde, and formic acid.

sulcus94It has been established that aspartame is dangerous to people with phenylketonuria or PKU, a genetic disorder that causes deficiencies in the metabolism of phenylalanine. US products containing aspartame must carry a warning label for phenylketonurics. However, it is controversial as to whether aspartame is dangerous to people with normal metabolism. An in vivo binding study by Trocho et al (1998) showed radiolabeled aspartame administered to rodents was present six hours after administration as formaldehyde bound to the liver, brain, and other tissues. The researchers concluded that if aspartame is consumed in large doses, it may cause deleterious effects similar to those of acute methanol intoxication including cirrhosis of the liver. A study by Soffritti et al (2006) showed rats given high doses of aspartame had increased incidence of malignant tumors, leukemias, and lymphomas as compared to controls. Particularly they noticed increased cell carcinomas in the renal pelvis and increased malignant schwannomas in peripheral nerves.

sulcus95There have also been several case studies of people who consume large amounts of aspartame. These reports claim an increase in a wide range of health problems from nausea and headaches to more serious neurological symptoms. Mitch Solomon (not his real name), a friend of mine from DC, actually had symptoms of Multiple Sclerosis and epilepsy possibly due to high consumption of aspartame. While studying to get his law degree, he drank one to two liters of Diet Pepsi per day (about three to six cans.) During that time, he began to get paroxysmal attacks, presumably due to demyelination of peripheral nerves. “It was pretty dramatic,” he said. “I would have temporary paralysis of one side of my body and slurred speech.” The attacks became more frequent, sometimes multiple times in a minute, and more severe. Solomon’s doctor prescribed Dilantin, an anti-seizure medication, and advised him to avoid aspartame. He did, and within a few months the symptoms vanished despite getting off Dilantin. “The symptoms started when I started drinking a lot of Diet Pepsi, and stopped when I stopped drinking it,” he said.

There are a number of anecdotal complaints like Solomon’s of neurological symptoms due to aspartame consumption registered against the FDA (Maher & Wurtman 1987), but controversially, the FDA approved the use of aspartame as a food additive during the Reagan administration. The decision was highly politicized as the FDA commissioner Arthur Hull Hayes approved of the use of aspartame against the recommendation of the FDA Public Board of Inquiry. After retiring, Hayes went to work for Searle, the pharmaceutical company that originally synthesized aspartame.

In light of this evidence (and because I was traveling and had limited access to soda) I went cold turkey off Diet Coke for a few days. Within a day I started to get bad headaches and generally felt like crap so I gave up and bought a twelve pack. Thinking I was just missing the caffeine in soda, I’ve tried substituting coffee and tea for Diet Coke before too but strangely I would get cravings specifically for Diet Coke. Will I give up my Diet Coke habit? Probably not. Should I? Probably.



Maher T, Wurtman R. “Possible neurologic effects of aspartame, a widely used food additive”. Environ Health Perspect 75: 53–7, 1987.

Soffritti, Morando, et al., “First Experimental Demonstration of the Multipotential Carcinogenic Effects of Aspartame Administered in the Feed to Sprague-Dawley Rats.” Environmental Health Perspectives 114(3): 379-385, 2006.

C. Trocho, R. Pardo, I. Rafecas, J. Virgili, X. Remesar, J. A. Fernandez-Lopez and M. Alemany. “Formaldehyde derived from dietary aspartame binds to tissue components in vivo”. Life Sciences 63 (5): 337–349, 1998


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