We regard the possible inclusion of free glutamic acids as a potential MSG ingredient, as the free glutamic acids are what may cause adverse reactions in those sensitive to MSG.  While the FDA rules regarding labeling and glutamic acid are lax, other governments, such as Canada, recognize the potential issues for certain individuals and prohibits the use of “MSG Free” on any product unless it can be proven that there are no detectable glutamates in the product; this includes natural sources of free glutamates such as tomatoes and grapes (Source).

These can all cause reactions in those sensitive to glutamates, which is why we label it with an MSG icon – so that those sensitive to glutamates will have all relevant information available to them.  We consider information from all major health sources, such as research institutes and governmental agencies (both US and foreign), when determining what may or may not be controversial.