Food allergy is principally diagnosed by careful history and examination. When reactions occur immediately after certain food ingestion then diagnosis is straight forward and can be documented by using carefully performed tests such as the skin prick test (SPT) and the radioallergosorbent test RAST to detect specific IgE antibodies to specific food proteins and aero-allergens. However, false positive results occur when using the SPT when diagnosis of a particular food allergen is hard to determine. This can be confirmed by exclusion of the suspected food or allergen from the patient's diet. It is then followed by an appropriately timed challenge under careful medical supervision. If there is no change of symptoms after 2 to 4 weeks of avoidance of the protein then food allergy is unlikely to be the cause and other causes such as food intolerance should be investigated. This method of exclusion-challenge testing is the premise by which the<unk>  is built upon, as explained in the sections below. Vega machine testing, a bioelectric test, is a controversial method that attempt to measure allergies or food or environmental intolerances. Currently this test has not been shown to be an effective measure of an allergy or intolerance. Food intolerance due to pharmacological reaction is more common than food allergy and has been estimated to occur in 10% of the population. Unlike a food allergy, a food intolerance can occur in non-atopic individuals. Food intolerances are more difficult to diagnose since individual food chemicals are widespread and can occur across a range of foods.<unk>  of these foods one at a time would be unhelpful in diagnosing the sensitivity. Natural chemicals such as benzoates and salicylates found in food are identical to artificial additives in food processing and can provoke the same response. 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. In addition, chemicals often exhibit dose-response relationships and so the food may not trigger the same response each time. There is currently no skin or blood test available to identify the offending chemical(s), and consequently,<unk> s aimed at identifying food intolerances need to be carefully designed. All patients with suspected food intolerance should consult a physician first to eliminate other possible causes. The<unk>  must be comprehensive and should contain only those foods unlikely to provoke a reaction in a patient. They also need to be able to provide complete nutrition and energy for the weeks it will be conducted. Professional nutritional advice from a dietitian or nutritionist is strongly recommended. Thorough education about the<unk>  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<unk> , records are kept of all foods eaten, medications taken, and symptoms that the patient may be experiencing. Patients are advised that withdrawal symptoms can occur in the first weeks on the<unk>  and some patients may experience symptoms that are worse initially before settling down. While on the diet some patients become sensitive to fumes and odours, which may also cause symptoms. They are advised to avoid such exposures as this can complicate the<unk>  and challenge procedures. Petroleum products, paints, cleaning agents, perfumes, smoke and pressure pack sprays are particular chemicals to avoid when participating in an<unk> . Once the procedure is complete this sensitivity becomes less of a problem. Clinical improvement usually occurs over a 2 to 4 week period; if there is no change after a strict adherence to the<unk>  and precipitating factors, then food intolerance is unlikely to be the cause. A normal diet can then be resumed by gradually introducing suspected and eliminated foods or chemical group of foods one at a time. 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<unk>  is not usually recommended during pregnancy, although a reduction in suspected foods that reduce symptoms can be helpful.
Elimination diet
Low-FODMAP diet
Low-fiber/low-residue diet
Cotton ball diet
Feingold diet
Gluten-free diet
Plant-based diet
Stillman diet