In addition to the rigorous review by the FDA, research on aspartame has been evaluated by numerous governmental and medical authorities including the American Medical Association Council on Scientific Affairs, the American Academy of Pediatrics Committee on Nutrition, the American Diabetes Association, the Academy of Nutrition and Dietetics (formerly the American Dietetic Association), the American Cancer Society, the American Dental Association, the American Council on Science and Health, the Epilepsy Institute, the European Food Safety Authority, and the Joint Expert Committee on Food Additives of the United Nations Food and Agriculture Organization and the World Health Organization.

Some critics claim that aspartame's breakdown components (aspartic acid, phenylalanine, methanol) could have harmful effects. However, those claims are unfounded. Aspartic acid and phenylalanine are building blocks of protein that are found in all protein-containing foods. Methanol is a natural breakdown product of many foods such as fruit and vegetable juices. The FDA reviewed animal, clinical and consumption studies submitted by the sweetener's manufacturer, as well as the existing body of scientific data, and "concluded that the studies demonstrated the safety of these components."

The FDA approved aspartame in 1981 for use in tabletop sweeteners and various foods and dry beverage mixes. It was the first low-calorie sweetener approved by the FDA in more than 25 years. In 1983, the FDA approved the use of aspartame in carbonated beverages. Since then, aspartame has been approved for use in any food or beverage. 

In addition to the FDA, aspartame has been reviewed and determined to be safe by the Joint Expert Committee on Food Additives (JECFA) of the United Nations Food and Agriculture Organization and the World Health Organization, the European Food Safety Authority, and the regulatory bodies of more than 100 countries. 

Prior to its regulatory approval, aspartame underwent one of the most rigorous testing programs and thorough regulatory reviews in food ingredient history. Extensive metabolism, pharmacology and toxicology studies were conducted with aspartame on animals. Studies were also done in normal humans, both adults and children, as well as in special sub-populations, such as individuals with phenylketonuria, obese individuals, diabetics and lactating females. Today scientists continue to conduct new studies on this sweetener as they do many other ingredients used in the food supply. The FDA also monitors and evaluates all research on this and other food ingredients.