Aspartame is the generic name for
Nutrasweet brand sweetener.
I've heard that corn is used in the production of aspartame, but I
don't have an authoritative source for this claim. Aspartame is made
from two amino acids (aspartic acid and phenylalanine) and
methanol. Amino acids are a major corn product, according to the Corn Refiners Association list of corn products, but it
doesn't say which ones. Methanol can be made from corn but rarely is
in practice. I've never experimented to see if I react to foods
containing Nutrasweet.
If you use packaged Nutrasweet
(as opposed to eating prepared foods containing it), be aware that it's
packaged with dextrose. This is also true of
saccharin. You should also be aware that aspartame's
safety is a controversial topic. See, for example, The Aspartame Controversy,
some Articles on
Nutrasweet(tm) from Usenet, or the Aspartame Consumer Safety
Network.