Monosodium Glutamate often appears on lists of food ingredients that definitely do contain gluten, or may contain gluten.
It is a fact that it is technically possible to make MSG from wheat. However this is not the usual case. In addition, the process of creating MSG uses an acid to break down the original components of the source food product in such a way that any proteins are broken down into their original components. One of these original components is Glutamic Acid. That is used to make MSG.
So, firstly the source food product used to make MSG is either rarely or never wheat.
Secondly, if the source food product was wheat, then the gluten component is destroyed in the process of breaking it down into Glutamic Acid.
Therefore, I conclude from looking at the food science involved that MSG can be expected to be gluten free.
Some people do not trust their own ability to interpret the food science, and instead rely on a trusted authority figure to tell them what they should or should not eat. This is not an unusual position in the celiac community. For those people I offer this quotation from the Canadian Celiac Association:Monosodium Glutamate (MSG)MSG is the sodium salt of glutamic acid, an amino acid found in many foods. It has been produced from both wheat gluten and sugar beet molasses but is now produced almost entirely from the latter in a highly purified form. Most authorities agree that it is harmless. There should be no concern among Celiacs about the use of foods containing MSG.
You can see this at:http://www.celiac.ca/Articles/Fall1990-1.html