I do not know the answer to this, but I am often a bit skeptic about this kind of stuff…. I just read about guar gum here and I guess it can have traces of soy left in it if not cleaned enough..

“Although some studies have found an allergic sensitivity to guar gum develop in a few rare individuals after working in an industrial environment involving much higher exposure than is common[17], almost all reported allergic reactions are due to impurities in guar gum, especially soy protein, which can make up as much as 10% of the content of commercial guar products.”

(This is from Wikipedia, which I know can’t always be trusted.)

Makes me wonder if a manufacturer can know for sure if the Xanthan Gum they buy from another company is really safe or not…. But just guessing here.