MSG and hydrolyzed vegetable protein induced headache: review and case studies.

Monosodium glutamate (MSG), an established headache trigger, has become far more prevalent in canned, packaged and prepared foods over the past decade. The presence of MSG in food may be difficult to detect since the terms "natural flavor," "flavoring," or "hydrolyzed vegetable protein (HVP)," all may appear on food labels to refer to MSG, according to current FDA food labeling codes. HVP typically contains 10-30% MSG. Case studies are presented in which the elimination of all food sources of MSG resulted in decreased headache frequency. Information and food lists helpful in identifying dietary MSG and HVP are presented. When patients are put on an MSG-free trial diet, attention needs to be given to identification of the wide variety of foods containing MSG and HVP.