Of the 2700 or so chemicals that are added to our food supply as preservatives, dyes and sweeteners, aspartame is perhaps the most well known. Although it has the same caloric value as sugar of 4cal/g, it is about 200 times sweeter and one liter of diet soda contains approximately 500mg of aspartame. As a consequence, much less is used to sweeten a food or beverage compared to sugar. Aspartame is converted by the body into phenylalanine, aspartic acid and methanol.
Although only 10% of aspartame is converted to methanol, this amount could become significant if large amounts of diet soda (which is a common source) are consumed. Another potential problem would be in those whose folate status is low. Folate comes from green leafy vegetables, legumes, citrus fruits, beets and whole grains. Methanol is metabolized into formate, and in individuals with low folate status, this substance builds up and increases oxidative damage in the brain.
Another potential problem with aspartame sweetened sodas occurs when it is stored on the grocery store shelf, or in your pantry. If indoor temperatures reach 30 degrees Celsius, up to 12% of aspartame is converted into diketopiperazine or DKP for short. As DKP is a small molecule, it has the potential to act as a hapten, or immune system stimulating agent that when combined with other proteins can cause food sensitivities. This would explain the reactions to aspartame containing foods that many patients complain of.
The intervention here is simply to limit your exposure to aspartame, and choose an alternative such as stevia or xylitol, which have beneficial side effects of reducing heartburn and fighting tooth decay respectively.
Be Well and Be Zen