Aspartame's Side Effects On The Nervous System

Aspartame is an artificial sweetener used as a sugar substitute in many foods and drinks. It is manufactured from phenylalanine and aspartic acid, two amino acids that occur naturally in food and our bodies. The U.S. Food and Drug Administration deemed aspartame safe for human consumption and approved it for use in the United States in 1981. It has also been approved for use in more than 90 other countries. Regardless of government approval, its safety is continually questioned, and many studies have investigated possible harmful effects of aspartame.

Aspartame and Methanol Poisoning

Methanol, toxic in large amounts, is present in a variety of food. A serving of fruits and vegetables has more methanol than a serving of aspartame. Foods naturally containing methanol also contain ethanol, the antidote for methanol poisoning, leading many to believe aspartame is dangerous because it doesn't have ethanol. This logic would only be valid if the food delivered a toxic dose, but a study published in the February 1981 issue of the "Journal of Toxicology and Environmental Health" and another published in "Metabolism" in April 1989 found that adults consuming more than 50 times the typical serving of aspartame did not get methanol poisoning. Similar findings in 1-year-olds were published in the "Journal of Nutrition" in 1983. The liver converts methanol to formaldehyde, which the body rapidly uses to make essential compounds like DNA. If the body doesn't need formaldehyde, it quickly converts it to formic acid and excretes it.

Studies Don't Support Side Effects

Most claims suggesting a link between aspartame and nervous system problems blame long-term exposure to methanol or formaldehyde. Physiologically this is not possible. The only product the body is exposed to long-term is formic acid, and if the amount exceeds the body's ability to excrete it, it is an immediate medical emergency. Other claims implicate different byproducts of aspartame in neurodegenerative diseases, mood changes, brain cancer and seizures. A study published in the May 1990 issue of "Journal of Clinical Pharmacology" observed no association between aspartame consumption and cognitive function, reaction time or mood. A study published in "Cancer, Epidemiology, Biomarkers & Prevention" in September 2006 showed no relationship between aspartame intake and incidence of brain cancer. A study from "Epilepsia" in March 1995 recruited self-reported aspartame-sensitive individuals and reported no clinical seizures, although electrographic seizures were recorded in two subjects who were on the placebo.

Science Says It's Safe

In 2009, the American Dietetic Association conducted a review of the studies investigating effects of aspartame on the nervous system. After assessing 16 peer-reviewed, human-subject research studies, the ADA concluded there was no evidence that aspartame contributes to or causes elevated blood methanol or formate levels, brain cancer, seizures, or changes in memory or mood.

Aspartame and Diet

Manufacturers use aspartame in the food supply to reduce sugar and calorie levels based on findings that it aids weight loss and doesn't cause harm. Despite scientific evidence asserting its safety, some still choose to avoid aspartame. It is not necessary to consume it, and many alternative products are available. People with phenylketonuria, a rare condition in which a person cannot break down phenylalanine, should avoid aspartame-containing products. These products should carry a warning label, but check for aspartame on the ingredient list to be sure. It is typically found in sugar substitutes such as NutraSweet or Equal, diet soft drinks, sugar-free products, and some vitamins and medicines.