Food Allergies and the Exclusion Diet

Going on an exclusion diet is probably the most common way to identify food triggers. You note down which foods you are eating alongside any symptoms you are experiencing, and then cut out a different food and repeat the process. 

Foods that are identified as causing symptoms are often caused 'trigger' foods, because they have triggered the symptoms. 

These triggers will be different in every sufferer, but there are some common foods which seem to cause problems for many people. Such as: 

·          Alcohol                                                                             

·          Red meat 

·          Wheat and/or gluten (gluten is found in wheat, oats, barley and rye) 

·          Citrus fruits 

·          Bran 

·          Artificial sweeteners such as Aspartame or Sorbitol 

·          Poultry skin and dark meat 

·          Carbonated drinks 

·          Coffee 

·          Dairy 

·          Fried foods 

·          Oils 

This is by no means a comprehensive list, and unfortunately an allergy sufferer may have to spend time working out which, if any, of the foods causes them the most problems. 

That being said, the most common foods tested by this kind of diet are wheat and gluten-containing products such as bread and pasta, and dairy products. You may even find that simply cutting out gluten or dairy improves your symptoms so significantly that there is no need to test other foods. 

It is advisable that you substitute foods for any trigger foods that you find - such as using gluten-free flour for baking or the use of rice or potatoes as food staples rather than bread. 

Why a Doctor might recommend an Exclusion Diet 

It can be difficult to discern which foods might be causing allergic symptoms. An elimination diet in which likely allergens are removed and then added back one by one may be useful as a diagnostic tool. 

You may notice that some foods cause immediate symptoms and so can also be identified as trigger foods. For example, some allergy sufferers could find that eating fatty or fried foods causes them to suffer from diarrhoea soon after consuming those foods - that then would be an easily identifiable trigger food. 

This is not always the case however and other food-related allergic reactions may present themselves so rapidly, or obviously, and therefore will not be so easily diagnosable. 

Other diagnostic tests may rarely return false negatives (if they indicate a patient is not allergic to a given food, the patient has at least a 95 percent likelihood of not being allergic), but they are fairly likely to return false positives (they show the patient is allergic to a given food, when that may not be the case). 

So unless the patient has experienced anaphylaxis before taking diagnostic tests, doctors will often recommend an elimination diet - to see if symptoms improve.  The doctor may even follow this up with a double-blind food test - one in which neither the doctor nor the patient is aware of whether the patient is eating the likely allergen – just to confirm the test results. 

For more information, read a our review of the Exclusion Diet

Written by

Darren Gray