My supplementary info for anyone who's interested: 

In simple terms, aspartame is a molecule made up of two amino acids, which are the building blocks of protein, and one methanol molecule. 

If the word 'acid' worries you then remember that vitamin C is actually ascorbic acid. 

One of the amino acids (phenylalanine) we cannot live without, therefore it is called an 'essential amino acid'. it is found in nearly all foods containing protein: meat of all kinds, dairy products, nuts, beans, tofu etc. We would simply die without consuming it. However, there are some people (I seem to remember that it's predominantly men) who have a deficiency of an enzyme which is necessary to properly metabolize phenylalanine. They are called phenylketonurics and must follow a strict low protein diet to avoid all food sources that have high phenylalanine content.

To get adequate amounts of other amino acids found in protein people with PKU also have to take a special formula which is usually in the form of a liquid.

The other is amino acid in aspartame is aspartic acid.

Both amino acids are completely natural and are present in the proteins that comprise a significant percentage of what you and I and living organisms are made.

Aspartame is digested just like any other protein. On digestion, aspartame breaks down in the gastrointestinal tract to small amounts of common dietary components including its constituent amino acids.

We consume these same components in much greater amounts in common foods, such as milk, meat, fruits and vegetables.

The body handles these amino acids in the same way it handles them from other food sources. Neither aspartame nor its components accumulates in the body over time.

The third component of aspartame is methanol, which is also a natural by-product of the metabolism 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.

During the metabolism 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.

Perhaps now you can see how it's so difficult to set things straight. Anyone can claim anything, e.g. 'kinesiology can cause cancer', but it takes time and effort to get science across, and then the language is not necessarily easy to understand.

See also: