The following questions came into the Aspartame Resource Center. We asked Molly Gee, MEd, RD, LD to respond.
What is the metabolic breakdown of aspartame?
Aspartame is made by joining two amino acids, aspartic acid and phenylalanine, with a third component as a methyl ester. Amino acids are the building blocks of protein and aspartame is digested as a protein. Aspartic acid and phenylalanine are also found naturally in protein containing foods, including meats, grains and dairy products. Methyl esters are also found naturally in many foods such as fruits and vegetables and their juices.
During digestion, aspartame breaks down into three components (aspartic acid, phenylalanine and a small amount of methanol), which are then absorbed into the blood and used in normal body processes. The amounts of these components from aspartame are small. For example, a serving of nonfat milk provides about 6 times more phenylalanine and 13 times more aspartic acid compared to an equivalent amount of diet beverage sweetened 100% with aspartame. Likewise, a serving of tomato juice provides about 6 times more methanol as compared to an equivalent amount of diet beverage with aspartame. These components are used in the body in the same ways as when they are also derived from common foods and beverages. Neither aspartame nor its components accumulates in the body over time.
How many milligrams of aspartame are in a diet soda?
One can of diet soda contains about 160 mg of aspartame. The acceptable daily intake (ADI) is established by the FDA and is the amount of a food additive that can be consumed daily for a lifetime without adverse affects. The ADI of aspartame is 50 mg/kg of body weight per day (22 cans of a diet soft drink for a 175 pound man; 15 cans for a 120 pound woman). This far exceeds the typical consumption of diet soft drinks
Molly Gee, Houston, TX, is a registered dietitian and provides expert counsel to the Aspartame Resource Center.