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The science of nutrition and healthy eating
The science of nutrition and healthy eating

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3 Diagnosing and managing a food allergy and food intolerance

You can diagnose an allergy using four methods:

  1. measure antibody IgE using the Radio Allergo Sorbent Test (RAST test) because the allergen protein initiates a reaction
  2. skin prick tests done by a qualified health care professional
  3. exclude the food and note any changes in a ‘food and symptoms’ diary
  4. food challenge using a very small amount of the food allergen, this must be done in a medical facility where there is resuscitation equipment.
An image of someone having blood taken from their arm.
Figure 6 Blood test

These methods all help to build a clinical picture for diagnosis of this kind of allergy which causes people a lot of distress.

It is important to:

  • be diagnosed using validated methods
  • manage the condition by avoiding the food if you have an allergy or knowing how much you can have if you have an intolerance
  • know what to do if the response happens again, especially anaphylaxis.

Don’t be fooled by some claims for allergy testing by some commercial companies. They are not validated tests and can give false positive results. They often use the Multi-Allergen Screening Test (MAST) but, without the detailed clinical history, a diagnosis can be difficult.

The advice they give can result in restrictive diets that can cause malnutrition. Have you ever experienced a paper cut? What happens? Well, it hurts and then the area becomes red and raised. This is a natural immune response. It does not mean you are allergic to paper!

Irritable bowel has been mentioned. This is when the bowel has become sensitive to some foods and can cause the symptoms of food intolerance. You have probably heard of IBS.