If you look at the Food and Drug Regulations, Division 16, Section B.16.100. You will see that there are only a certain number of foods that this ingredient can be used in, and depending on what food it is being used it, there is a limit to the amount allowed to be present depending on what food product that it is used in.
When a customer asks you to remove the ingredient, it is more than likely because a CFIA inspector has identified that the presence of the ingredient is not allowed in a standardized product or that it exceeds the limit allowable.
Please note that if this was present in a Meat product, similar information can be found in Schedule I of the Meat Inspection Regulations. The use of that particular ingredient may not be allowed within standardized meat product.