Tests with humans consuming much greater levels of aspartame than the ADI have shown no adverse side effects. Aspartame's ADI is the sweetness equivalency of consuming one pound of sugar per day. This amount of sweetness would be difficult for an individual to consume during one day, let alone every day over many months or years. The American Medical Association's Council on Scientific Affairs reviewed research on aspartame and found the sweetener to be safe. The American Dietetic Association also has concluded that moderate use of aspartame is acceptable as part of a healthful diet.
Methanol is a natural and harmless by-product of metabolization of many commonly consumed foods.
The methanol produced by the metabolism of aspartame is identical to that which is provided in much larger amounts from fruits, vegetables and their juices and is part of the normal diet. In fact, a glass of tomato juice provides 6 times as much methanol as a similar amount of diet soda. During the metabolization of aspartame in the gastrointestinal tract, methanol is released and then metabolized by normal body processes. Numerous scientific studies have shown that the methanol derived from aspartame does not accumulate in the body and thus cannot reach harmful levels. Aspartame is one of the most thoroughly studied ingredients in the food supply.