Where you live may affect the allergies you are prone to (Image: Gregor Schuster/Getty)

Get involved: Tell us your food allergies

WE WERE just settling down for our flight when the captain’s voice came over the PA system. “Ladies and gentlemen, I am sorry to disturb you, but we have a passenger on board who has a severe nut allergy. Could I ask you please not to open or eat any food that contains nuts for the duration of the flight? I am sorry for any inconvenience. We hope you enjoy your flight.”

It was no coincidence that at the time I was on my way to a conference on food allergy in Vienna, Austria. Hazel Gowland, food adviser to the The Anaphylaxis Campaign in the UK, was travelling for the same reason, and it was for her benefit that the captain made his request.

While such an announcement may not be an everyday occurrence, most of us are familiar with the idea that peanuts can trigger a life-threatening allergic reaction. But peanuts aren’t the biggest concern in every country. Passengers from Greece, where peanut allergy is rather rare, might have been more concerned about the melon in the fruit salad. A passenger from the south of Italy might have pushed the in-flight apple juice to one side for fear that it might trigger a skin rash and stomach pains, a reaction that would puzzle a compatriot from northern Italy.

Why such regional differences exist is just one of the many mysteries surrounding food allergies. Why, for example, do some migrants from east Asia develop an allergy to jackfruit when …