http://cspinet.org/new/201112011.htmlThe vat-grown mold used to make the Quorn line of meat substitutes causes gastrointestinal distress and in some cases, life-threatening anaphylactic reactions, according to the nonprofit Center for Science in the Public Interest. The nutrition and food safety watchdog group has again urged the Food and Drug Administration to revoke its “Generally Recognized as Safe,” or GRAS, designation for the controversial fermented fungus. If the agency does intend to allow Quorn’s “mycoprotein” to remain on store shelves, it should at least require a prominent warning label, the group says.
You had me worried there, it's a big part of our diet as it's available in the UK, and we have the pretty strict Food Safety Agency that would have put a shutter on it well before now if it was an issue. It looks like people are more likely to be allergic to Soy or Dairy than to mycoprotein, perhaps it could be labelled as a possible allergen in the future, but certainly it wouldn't warrant banning.