In the US Maltodextrin is typically sourced from corn, potato or rice. If it is sourced from wheat, US labeling laws require wheat to be listed as an ingredient on the label.
Taken from the European Food Safety Journal:
“Wheat-based maltodextrins may contain low levels of proteins and peptides. It is not known at which levels of intake wheat-based maltodextrins would cause allergic reactions in wheat-allergic individuals. Nevertheless, taking into account the scientific information provided and in particular the levels of wheat proteins reported in wheat-based maltodextrins, the Panel considers that it is not very likely that this product will trigger a severe allergic reaction in susceptible individuals.”
Maltodextrin (like glucose syrup) is highly refined and both are unlikely to cause “severe” allergic reactions in those with wheat allergies. However, all allergies and individuals are different. It is always best to err on the side of caution and choose a non wheat sourced product if you have a wheat allergy.
For those who are on gluten free diets, and do not have a wheat allergy, the gluten free community considers both maltodextrin and glucose syrup safe.
Visit Gluten Free Living for a list of other safe ingredients.