Diagnosis of food allergy
A physical check-up will rule out other more obvious medical problems in the first instance.
A concise dietary history including a description of the symptoms and the foods suspected of triggering these symptoms.
A history of atopic disease in the family including any allergies to foods or other materials, any food intolerances including coeliac disease and incidences of asthma, hay fever, eczema, etc.
The patient may be instructed to keep a food diary of their eating habits, symptoms and medications to help pinpoint the problem.
An elimination diet may be used to link the symptoms with the food or foods causing them. This may not be advisable if the reaction has been severe.
If a food allergy is suspect after these investigations, more diagnostic methods are employed:
Skin prick tests are used to determine the reaction to a range of foods or to see if the problem could have been caused by other common allergens such as dust, cat hair or pollen. It can also give an indication of how strong the reaction is.
Blood tests are used to determine the strength of the immune system response to an allergen. This usually involves a radioallergosorbent or 'RAST' test in which the level of IgE antibodies – the kind specifically associated with a food allergic reaction – are measured.
Allergen provocation tests are generally regarded as being diagnostically the most definitive. The 'double-blind placebo-controlled food challenge' (DBPCFC) is used to administer the suspect allergenic food to the patient orally under clinical supervision. The DBPCFC can be risky for people who may have a severe food allergy and in this case is only carried out in a hospital setting with full