The secret of successful identification of food allergies is to give up sufficient foods to be able to feel well, then to re-introduce these foods one at a time, so that detecting a reaction is relatively easy. We call this elimination and challenge dieting. It rarely works to give up just one food at a time because anyone who is ill is almost certain to have more than one allergy. If it was simply one major allergen, the person would have spotted it eventually, as indeed some lucky people do. Dr Doris Rapp of New York coined an instructive term: the “eight nails in the shoe trap”. She points out that if you have eight nails sticking out in your shoe, and then pull just one of these nails, you will still not be comfortable – because of the other seven. It can be the same with multiple allergies. You have to work at it just that little bit harder.

Make no mistake, elimination diets can be tough; they should be. But it is important to remember that I am talking here of a trial diet, an experimental procedure. You do not need to stay on a tough diet long-term; indeed you are specifically cautioned not to do so, otherwise you run into problems caused by inadequate nutritional sources. The purpose of the strict diet is to isolate the culprits. Once you know these, you can eat most anything else. This means you shift into a maintenance diet, solely avoiding these offending foods, something you stay on for months or years. Almost anyone who feels much better by avoiding one or two foods has the will power to continue; the rewards are high!

Please don’t mix up these two grades of diet. You’ll suffer needlessly.