Medicine & Research

Examining the Safety of Aspartame

By Ellen Whipple Guthrie, Pharm.D.
For several years, an alarming and controversial report has been circulating on the Internet, claiming that the artificial sweetener aspartame can cause multiple sclerosis and a host of other ailments. Certain versions of the report even claim that MS symptoms will disappear if intake of aspartame is halted. MSFocus frequently receives letters questioning the truth of these allegations. Ellen Guthrie, Pharm.D. now explores the question, is aspartame safe?
Clinically speaking, we can never say that anything (drug, additive, food, device, etc.) is 100 percent safe. We can, however, examine the data and research and differentiate fact from fiction. The Internet is an excellent source of information, but this information is only as reliable as the person posting the information and only as accurate as the data that backs it up.
In 1965, chemist James Schlatter accidentally discovered the high-intensity sweetener known as aspartame. Before its approval in the early 1980s by the U.S. Food and Drug Administration, aspartame underwent extensive scientific studies that demonstrated its safety in both animals and humans. Since its approval, about 20 years ago, aspartame has been consumed in more than 6,000 products by hundreds of millions of people in hundreds of countries throughout the world. Aspartame is the ingredient that makes many foods (primarily colas) "light," "low-calorie," or "diet." Since it is impossible to detect all side effects in pre-marketing studies, aspartame has undergone extensive post-marketing surveillance to ensure that the additive is safe.
The metabolism of aspartame in the human body and the proposed toxicities from its metabolic components have concerned a lot of people and have been the emphasis of many postmarketing surveillance studies. Aspartame is metabolized by digestive enzymes and peptides to three common dietary components: amino acids, aspartic acid, and phenylalanine. Minute amounts of methanol can also be detected. Eating foods such as meat, dairy, fruits, and vegetables will also produce these same components, but in greater amounts than aspartame. For example, a glass of milk has six times more phenylalanine and 13 times more aspartic acid and a glass of tomato juice provides six times more methanol than a beverage the same size sweetened with 100 percent aspartame. Interestingly enough, it is impossible for humans to digest enough aspartame to raise the levels of these metabolic components to a dangerous level.
Anecdotal reports claiming that aspartame caused health problems increased in the days and weeks after aspartame was approved for use in carbonated beverages in 1983. These reports prompted the FDA to request an investigation by the Centers for Disease Control. The CDC analyzed more than 500 reports and the problems associated with aspartame were divided into two categories. Two-thirds of the people experienced neurological problems while one-quarter of the people experienced gastrointestinal problems. The neurological symptoms consisted of headaches, mood alterations, insomnia, dizziness, and fatigue. The gastrointestinal symptoms included abdominal pain, nausea, diarrhea, and vomiting. The CDC concluded, "The majority of symptoms were mild and are symptoms that are common in the general populace." The CDC also noted that there was no evidence supporting the claim that aspartame could cause certain diseases (i.e. multiple sclerosis, lupus, etc.).
While nothing can be considered 100 percent safe, aspartame has undergone extensive testing. With the exception of a few very mild side effects, aspartame appears to be quite safe. Those individuals, who experience problems after consuming aspartame, should eliminate foods and beverages that contain this sweetener from their diet.
Editor's Note:
The report claiming aspartame causes MS, often referred to as the Nancy Merkle hoax, is believed to have been circulating since 1995. The message is attributed to "Nancy Merkle," yet no one has come forward claiming to be the author. No credentials, research or sources are cited. This hoax first came to the attention of the Multiple Sclerosis Foundation in 1998, when those circulating it added the false claim that the MSF was suing the U.S. Food and Drug Administration to halt the sale and use of aspartame. The MSF neither condemns nor endorses aspartame, and has never filed suit against the FDA.
(Last reviewed 7/2009)