With reasons being unknown about the cause of stuttering, there is a theory going around which states the connection between food allergies and stuttering. According to this notion, the allergy to certain foods causes the sympathetic nervous system to be activated rather than the para-sympathetic nervous system. As a result, what follows is an increase in the level of anxiousness in the stutterer stimulating the stutter and worsening it.
There has been no conclusive evidence to show that certain foods worsen or aggravate this condition in a person when he is already a stutterer. But there have been instances where sufferers have felt remarkable improvement in their condition with the elimination of certain items from their diet. Most people are unaware of the connection between stuttering and food. This link cannot be assumed to exist in all stutterers but there is a possibility that some sufferers maybe experiencing this problem because of their diet. It is advisable that you check with a gastroenterologist to ensure that their food intake is not a possible reason for their stutter.
The most common food allergy prevalent in stutterers is that of gluten which has been found to aggravate the stutter. Gluten is a substance found in wheat and hence is present in most of the bread varieties. The consumption of gluten by the stutterer worsens his stutter, sometimes aggravating it to such an extent that the stutterer is not even able to put in a complete sentence. The slurring and stuttering become extremely bad with the intake of gluten. Once the stutterer ceases to take in gluten in any form, his stuttering is back to its normal level. But this gluten aversion could also be because of some other bigger disorders like Celiac and should immediately be checked with a doctor.