Noreen, I'll be watching the programme (it's on in an hour!) I do like the 'Trust Me' series.
As a teacher I had to be very careful watching over my pupils with allergies. We had special training to deal with anaphylactic shock, Epipens etc. And my poor husband suffers the torments of hell with hayfever from early Spring to late summer.
I don't believe any of these things are loony fads. People know when they feel reactions, and one should listen to them. It must be miserable to suffer from an intolerance or an allergy. Coeliac disease can result in severe malnutrition, and nut allergies can actually be fatal if adrenaline isn't administered very quickly.