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* [[Sodium phosphates]]
* [[Sodium phosphates]]
* [[Allergy]]
* [[Allergy]]

==External links==
*[http://www.sswahs.nsw.gov.au/rpa/allergy/ Royal Prince Alfred Hospital Allergy Unit]
*[http://www.fedupwithfoodadditives.info/ Food Intolerance Network]
*[http://www.allergyuk.org/allergy_intol.aspx Allergy UK]





Revision as of 21:40, 1 February 2010

An elimination diet is a method of identifying foods that an individual cannot consume without adverse effects.[1] Adverse effects may be due to food allergy, food intolerance, other physiological mechanisms(such as metabolic or toxins),[2] or a combination of these. When the mechanism is unknown, but a food is suspected, the mechanism may be described as a food sensitivity or a food hypersensitivity. Elimination diets typically involve entirely removing a suspected food from the diet for a period of time from two weeks to two months, and seeing whether symptoms resolve during that time. In extreme cases, an oligoantigenic diet may be tested.

Common reasons for undertaking an elimination diet include suspected food allergies and suspected food intolerances. An elimination diet might remove one or more common foods, such as eggs or milk, or it might remove one or more minor or non-nutritive substances, such as artificial food colorings.

An elimination diet relies on trial and error to identify specific allergies and intolerances. Typically, if symptoms resolve after the removal of a food from the diet, then the food is reintroduced to see whether the symptoms reappear. This challenge-dechallenge-rechallenge approach is particularly useful in cases with intermittent or vague symptoms.[3]

The terms exclusion diet and elimination diet are often used interchangeably in the literature, and there is no standardised terminology. The exclusion diet can be a diagnostic tool or method used temporarily to determine whether a patient’s symptoms are food-related. The term elimination diet is also used to describe a "treatment diet", which eliminates certain foods for a patient.[2] [4][5]

Adverse reactions to food can be due to several mechanisms. Correct identification of the type of reaction in an individual is important, as different approaches to management are required. The area of adverse reactions to food has been controversial and the subject of ongoing research. It has been characterised in the past by lack of universal acceptance of definitions, diagnosis and treatment.[2][6]

Definitions

'Food hypersensitivity' is an umbrella term which includes food allergy and food intolerance. [7] [8] [9]

Food allergy is defined as an immunological hypersensitivity which occurs most commonly to food proteins such as egg, milk, seafood, shellfish, tree nuts, soya, wheat and peanuts, generally by production of IgE (immunoglobulin E) antibodies.

Food intolerance also now known as 'non-allergic food hypersensitivity' is defined as a non allergic abnormal physiological response to food. While true allergies are associated with fast-acting IgE responses, it can be difficult to determine the offending food causing an intolerance reaction because if the immune system is involved, the response is likely to be IgG mediated and takes place over a prolonged period of time. Thus the causative agent and the response are separated in time, and may not be obviously related. Food intolerance reactions may include pharmacologic, metabolic, toxic, but not psychological responses to foods or food components.

  • Metabolic food reactions are due to an inborn or acquired errors of metabolism of nutrients such as in diabetes melitus, lactase deficiency, phenylketonuria and favism. Toxic food reactions are caused by the direct action of a food or additive without immune involvement.
  • Pharmacological reactions are generally to low molecular weight chemicals which occur either as natural compounds such as salicylates, amines, or to artificially added substances such as preservatives, colouring, emulsifiers and taste enhancers including glutamate (MSG) [10] . These chemicals are capable of causing drug-like (biochemical) side effects in susceptible individuals.
  • Toxins may either be present naturally in food or released by bacteria or from contamination of food products.
  • Psychological reactions involve manifestation of clinical symptoms caused not by the food but by emotions associated with the food. The symptoms do not occur when the food is given in an unrecognisable form.

Elimination diets are useful to assist in the diagnosis of food allergy and pharmacological food intolerance. Metabolic, toxic and psychological reactions can be diagnosed by other means.[2][11][12]

Diagnosis

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 SPT skin prick test and RAST sensitive tests to detect specific IgE antibodies to specific food (proteins) and aero-allergens. However false positive results to SPT do occur, when diagnosis is doubtful it can be confirmed by exclusion of the suspected food or allergen from the patient followed by 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.[12][13] [14]

Food intolerance due to pharmacological reaction is more common than food allergy and has been estimated to occur in 10% of the population and unlike food allergy can occur in non-atopic individuals. It is also more difficult to diagnose. Individual food chemicals are widespread and can occur across a range of foods, such that eliminating one at a time is unhelpful. Natural chemicals such as benzoates and salicylates found in food are identical to artificial additives in food processing and can provoke the same response. As the specific component is not readily known and as the reactions are often delayed up to 48 hours after ingestion, it can be difficult to identify suspect foods. Added to that is that these 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) consequently elimination diets aimed at identifying food intolerances need to be carefully designed and exactingly applied. All patients with suspected food intolerance should consult a physician first to eliminate other possible causes.[2][11]

Elimination diet

The elimination diet must be comprehensive containing only those foods unlikely to provoke a reaction, but be able to provide complete nutrition and energy, for the weeks it will be applied, professional nutritional advice is needed. 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. Whilst on the elimination diet records are kept of all foods eaten, medications taken and severity of any symptoms. Patients are advised that withdrawal symptoms can occur in the first weeks on the elimination diet, some of the patients symptoms can flare or worsen initially before settling. Whilst on the diet some patients become sensitive to fumes and odours, which may cause symptoms. They are advised to avoid such exposures as this can complicate the elimination and challenge procedures. Particularly to petroleum products, paints, cleaning agents, perfumes, smoke and pressure pack sprays. 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 elimination diet 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 elimination diet is not usually recommended during pregnancy, although a reduction in suspected foods that reduce symptoms can be helpful.[2]

Challenge testing

Challenge testing is not carried out until all symptoms have cleared or improved significantly for five days after a minimum period on the elimination diet of two weeks. The elimination diet is continued throughout the challenge period. Open food challenges on wheat and milk can be carried out first. Followed by challenge with natural food chemicals then additives. Challenges can take the form of purified food chemicals or with foods grouped according to food chemical. Purified food chemicals are used in double blind placebo controlled testing, and food challenges involve foods containing only one suspect food chemical eaten several times a day over 3 to 7 days. If a reaction occurs patients must wait until all symptoms subside completely and then wait a further 3 days (to overcome a refractory period) before recommencing challenges. 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.

If any results are doubtful the testing is repeated, only when all tests are completed is a treatment diet determined for the patient. The diet restricts only those compounds to which the patient has reacted and over time liberalisation is attempted. In some patients food allergy and food intolerance can coexist, with symptoms such as asthma, eczema and rhinitis. In such cases the elimination diet for food intolerance is used for dietary investigation. Any foods identified by SPT or RAST as suspect should not be included in the elimination diet.[2][6][11][12][13][14][15][16][17][18][19]

History

The concept of the elimination diet was first proposed by Dr. Albert Rowe in 1926 and expounded upon in his book, Elimination Diets and the Patient's Allergies, published in 1941.[20]

In 1978 Australian researchers published details of an 'exclusion diet' to exclude specific food chemicals from the diet of patients. This provided a basis for challenge with these additives and natural chemicals. 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 futute DBPCT trials of such substances in food intolerance studies. [21][22]


References

  1. ^ "Allergies: Elimination Diet and Food Challenge Test". WebMD. Retrieved 2009-04-01.
  2. ^ a b c d e f g Clarke L, McQueen J, Samild A, Swain AR (1996). "Dietitians Association of Australia review paper. The dietary management of food allergy and food intolerance in children and adults" (PDF). Aust J Nutr Dietetics. 53 (3): 89–98. ISSN 1032-1322. OCLC 20142084.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  3. ^ Minford AM, MacDonald A, Littlewood JM (1982). "Food intolerance and food allergy in children: a review of 68 cases". Arch Dis Child. 57 (10): 742–7. doi:10.1136/adc.57.10.742. PMC 1627921. PMID 7138062. {{cite journal}}: Unknown parameter |month= ignored (help)CS1 maint: multiple names: authors list (link)
  4. ^ Laitinen K, Isolauri E (2007). "Allergic infants: growth and implications while on exclusion diets". Nestle Nutr Workshop Ser Pediatr Program. 60: 157–67, discussion 167–9. doi:10.1159/0000106367. PMID 17664903.
  5. ^ Barbi E, Berti I, Longo G (2008). "Food allergy: from the of loss of tolerance induced by exclusion diets to specific oral tolerance induction". Recent Pat Inflamm Allergy Drug Discov. 2 (3): 212–4. PMID 19076011.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  6. ^ a b Allen DH, Van Nunen S, Loblay R, Clarke L, Swain A (1984). "Adverse reactions to foods". Med J Aust. 141 (5 Suppl): S37–42. PMID 6482784.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  7. ^ Gerth van Wijk R, van Cauwenberge PB, Johansson SG (2003). "[Revised terminology for allergies and related conditions]". Ned Tijdschr Tandheelkd (in Dutch; Flemish). 110 (8): 328–31. PMID 12953386. {{cite journal}}: Unknown parameter |month= ignored (help)CS1 maint: multiple names: authors list (link) CS1 maint: unrecognized language (link)
  8. ^ Johansson SG, Bieber T, Dahl R; et al. (2004). "Revised nomenclature for allergy for global use: Report of the Nomenclature Review Committee of the World Allergy Organization, October 2003". J. Allergy Clin. Immunol. 113 (5): 832–6. doi:10.1016/j.jaci.2003.12.591. PMID 15131563. {{cite journal}}: Explicit use of et al. in: |author= (help); Unknown parameter |month= ignored (help)CS1 maint: multiple names: authors list (link)
  9. ^ Johansson SG, Hourihane JO, Bousquet J; et al. (2001). "A revised nomenclature for allergy. An EAACI position statement from the EAACI nomenclature task force". Allergy. 56 (9): 813–24. PMID 11551246. {{cite journal}}: Explicit use of et al. in: |author= (help); Unknown parameter |month= ignored (help)CS1 maint: multiple names: authors list (link)
  10. ^ Asero R, Bottazzi G (2007). "Chronic rhinitis with nasal polyposis associated with sodium glutamate intolerance". Int. Arch. Allergy Immunol. 144 (2): 159–61. doi:10.1159/000103229. PMID 17536215.
  11. ^ a b c Ortolani C, Pastorello EA (2006). "Food allergies and food intolerances". Best practice & research. Clinical gastroenterology. 20 (3): 467–83. doi:10.1016/j.bpg.2005.11.010. PMID 16782524.
  12. ^ a b c Pastar Z, Lipozencić J (2006). "Adverse reactions to food and clinical expressions of food allergy". Skinmed. 5 (3): 119–25, quiz 126–7. doi:10.1111/j.1540-9740.2006.04913.x. PMID 16687980.
  13. ^ a b Schnyder B, Pichler WJ (1999). "[Food intolerance and food allergy]". Schweizerische medizinische Wochenschrift (in German). 129 (24): 928–33. PMID 10413828.
  14. ^ a b Kitts D, Yuan Y, Joneja J; et al. (1997). "Adverse reactions to food constituents: allergy, intolerance, and autoimmunity". Can. J. Physiol. Pharmacol. 75 (4): 241–54. doi:10.1139/cjpp-75-4-241. PMID 9196849. {{cite journal}}: Explicit use of et al. in: |author= (help)CS1 maint: multiple names: authors list (link)
  15. ^ Sullivan PB (1999). "Food allergy and food intolerance in childhood". Indian journal of pediatrics. 66 (1 Suppl): S37–45. PMID 11132467.
  16. ^ Vanderhoof JA (1998). "Food hypersensitivity in children". Current opinion in clinical nutrition and metabolic care. 1 (5): 419–22. doi:10.1097/00075197-199809000-00009. PMID 10565387.
  17. ^ Liu Z, Li N, Neu J (2005). "Tight junctions, leaky intestines, and pediatric diseases". Acta Paediatr. 94 (4): 386–93. PMID 16092447.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  18. ^ MacDermott RP (2007). "Treatment of irritable bowel syndrome in outpatients with inflammatory bowel disease using a food and beverage intolerance, food and beverage avoidance diet". Inflamm Bowel Dis. 13 (1): 91–6. doi:10.1002/ibd.20048. PMID 17206644.
  19. ^ Carroccio A, Di Prima L, Iacono G; et al. (2006). "Multiple food hypersensitivity as a cause of refractory chronic constipation in adults". Scand J Gastroenterol. 41 (4): 498–504. doi:10.1080/00365520500367400. PMID 16635922. {{cite journal}}: Explicit use of et al. in: |author= (help)CS1 maint: multiple names: authors list (link)
  20. ^ Rowe, A. Elimination Diets and the Patient's Allergies. 2nd Edition. Lea & Febiger, Philadelphia, PA: 1944
  21. ^ Gibson AR, Clancy RL (1978). "An Australian exclusion diet". Med. J. Aust. 1 (5): 290–2. PMID 661687. {{cite journal}}: Unknown parameter |month= ignored (help)
  22. ^ Gibson A, Clancy R (1980). "Management of chronic idiopathic urticaria by the identification and exclusion of dietary factors". Clin. Allergy. 10 (6): 699–704. PMID 7460264. {{cite journal}}: Unknown parameter |month= ignored (help)

See also

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