#9399
Kate Osborne
Peter Osborne
Keymaster

His problem is not your problem.  People are different.  If he really wants to understand, have him watch the first Glutenology video.  It is not a simple one liner answer that can be given.  Expecially if he is already resistant to hearing the truth.  Bottom line:  different people react more or less violently to allergies (delayed or acute) and intolerances. 

All the best,

Dr. O