[4] The exclusion diet can be a diagnostic tool or method used temporarily to determine whether a patient's symptoms are food-related.
Correct identification of the type of reaction in an individual is important, as different approaches to management may be required.
Using this approach, the role played by dietary chemical factors in the pathogenesis of chronic idiopathic urticaria (CIU) was first established and set the stage for future DBPCT trials of such substances in food intolerance studies.
However, false positive results occur when using the SPT when diagnosis of a particular food allergen is hard to determine.
[21][22][23] This method of exclusion-challenge testing is the premise by which the Elimination Diet is built upon, as explained in the sections below.
Since a specific component is not readily known and the reactions are often delayed up to 48 hours after ingestion, it can be difficult to identify suspect foods.
Thorough education about the elimination diet is essential to ensure patients and the parents of children with suspected food intolerance understand the importance of complete adherence to the diet, as inadvertent consumption of an offending chemical can prevent resolution of symptoms and render challenge results useless.
While on the elimination diet, records are kept of all foods eaten, medications taken, and symptoms that the patient may be experiencing.
Petroleum products, paints, cleaning agents, perfumes, smoke and pressure pack sprays are particular chemicals to avoid when participating in an elimination diet.
Clinical improvement usually occurs over a 2 to 4 week period; if there is no change after a strict adherence to the elimination diet and precipitating factors, then food intolerance is unlikely to be the cause.
Gradually increasing the amount up to high doses over 3 to 7 days to see if exacerbated reactions are provoked before permanently reintroducing that food to the diet.
A strict elimination diet is not usually recommended during pregnancy, although a reduction in suspected foods that reduce symptoms can be helpful.
[2] Challenge testing is not carried out until all symptoms have cleared or improved significantly for five days after a minimum period of two weeks on the elimination diet.
Patients with a history of asthma, laryngeal oedema or anaphylaxis may be hospitalised as inpatients or attended in specialist clinics where resuscitation facilities are available for the testing.