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Food Sensitivities

September 2010

Manifestations of food allergy: evaluation and management.

The term “food allergy” refers to adverse immunologic reactions to food. Food allergy is usually mediated by IgE antibody directed to specific food proteins, but other immunologic mechanisms can also play a role. The primary target organs for food allergic reactions are the skin, the gastrointestinal tract and the respiratory system. Both acute reactions (hives and anaphylaxis) and chronic disease (asthma, atopic dermatitis and gastrointestinal disorders) may be caused or exacerbated by food allergy. The foods most commonly causing these reactions in children are milk, egg, peanuts, soy, wheat, tree nuts, fish and shellfish; in adults, they are peanuts, tree nuts, shellfish and fish. The diagnosis of food allergy requires a careful search for possible causes, confirmation of the cause(s) with supporting tests, including specific tests for IgE (i.e., prick skin tests, radioallergosorbent tests) and, in some cases, oral food challenges. Treatment consists of elimination of the causal food(s) along with medical treatment, including the prompt self-administration of epinephrine in the event of a serious reaction.

Am Fam Physician. 1999 Jan 15;59(2):415-24

Dietary aspects of adverse reactions to foods in adults.

Dietary considerations play an important role in the diagnosis, treatment and management of immunologic and nonimmunologic reactions to foods. Food diaries and trial elimination diets may prove helpful in identifying the responsible foods. Elimination diets must be monitored carefully for nutritional adequacy and should be used no longer than absolutely necessary; in some instances appropriate vitamin and mineral supplementation may be necessary. Ideally the identification of foods that provoke symptoms should be confirmed by means of double-blind challenge testing. Avoidance of some problem foods is unlikely to cause nutritional problems, but the practical and nutritional implications of allergies to staple foods such as cow’s milk, eggs and wheat are far greater. Nonimmunologic adverse reactions that may mimic food allergic reactions include gastrointestinal disorders, sensitivity to food additives and psychologically based adverse reactions. There may be some degree of tolerance in metabolic disorders, which makes dietary management easier. Sensitivity to food additives necessitates careful scrutiny of food labels. In psychologic adverse reactions to foods, several foods are often involved, which increases the risk of nutritional problems.

CMAJ. 1988 Oct 15;139(8):711-8

Clinical aspects of gastrointestinal food allergy in childhood.

Gastrointestinal food allergies are a spectrum of disorders that result from adverse immune responses to dietary antigens. The named disorders include immediate gastrointestinal hypersensitivity (anaphylaxis), oral allergy syndrome, allergic eosinophilic esophagitis, gastritis, and gastroenterocolitis; dietary protein enterocolitis, proctitis, and enteropathy; and celiac disease. Additional disorders sometimes attributed to food allergy include colic, gastroesophageal reflux, and constipation. The pediatrician faces several challenges in dealing with these disorders because diagnosis requires differentiating allergic disorders from many other causes of similar symptoms, and therapy requires identification of causal foods, application of therapeutic diets and/or medications, and monitoring for resolution of these disorders. This review catalogs the spectrum of gastrointestinal food allergies that affect children and provides a framework for a rational approach to diagnosis and management.

Pediatrics. 2003 Jun;111(6 Pt 3):1609-16

Food allergen avoidance in the prevention of food allergy in infants and children.

Food allergy afflicts an increasing number of infants and children and is associated with both clinical and familial burdens. To help lessen this burden, the Nutritional Committees from the American Academy of Pediatrics and jointly the European Society for Pediatric Allergology and Clinical Immunology and the European Society for Pediatric Gastroenterology, Hepatology, and Nutrition published recommendations to prevent and treat food allergy. Although there is much in common with these recommendations, differences exist. This review compares, contrasts, and reconciles them, presenting the evidence that has led to their statements.

Pediatrics. 2003 Jun;111(6 Pt 3):1662-71

Treating irritable bowel syndrome with a food elimination diet followed by food challenge and probiotics.

OBJECTIVE: In Irritable Bowel Syndrome, the gut-associated immune system may be up-regulated resulting in immune complex production, low-grade inflammation, loss of Class I bacteria, and translocation of inflammatory mediators and macromolecules outside of the GI lumen. Since food intolerance may be one of the reasons for this upregulation, our goal was to investigate the role of food intolerance in IBS patients. METHODS: In this open label pilot study, we enrolled 20 patients with IBS by Rome II criteria (15 women, ages 24-81) who had failed standard medical therapies in a tertiary care GI clinic. Baseline serum IgE and IgG food and mold panels, and comprehensive stool analysis (CSA) were performed. Breath-hydrogen testing and IBS Quality-of-Life (QOL) questionnaires were obtained. Patients underwent food elimination diets based on the results of food and mold panels followed by controlled food challenge. Probiotics were also introduced. Repeat testing was performed at 6-months. We followed up with this cohort at 1 year after trial completion to assess the reported intervention and for placebo effect. RESULTS: Baseline abnormalities were identified on serum IgG food and mold panels in 100% of the study subjects with significant improvement after food elimination and rotation diet (p < 0.05). Significant improvements were seen in stool frequency (p < 0.05), pain (p < 0.05), and IBS-QOL scores (p < 0.0001). Imbalances of beneficial flora and dysbiotic flora were identified in 100% of subjects by CSA. There was a trend to improvement of beneficial flora after treatment but no change in dysbiotic flora. The 1-year follow up demonstrated significant continued adherence to the food rotation diet (4.00 +/- 1.45), minimal symptomatic problems with IBS (4.00 +/- 1.17), and perception of control over IBS (4.15 +/- 1.23). The continued use of probiotics was considered less helpful (3.40 +/- 1.60). CONCLUSION: These data demonstrate that identifying and appropriately addressing food sensitivity in IBS patients not previously responding to standard therapy results in a sustained clinical response and impacts on overall well being and quality of life in this challenging entity.

J Am Coll Nutr. 2006 Dec;25(6):514-22

Serum IgG subclass antibodies to a variety of food antigens in patients with coeliac disease.

Levels of serum IgA, IgG, and IgG subclass antibodies to a variety of dietary antigens were determined by enzyme linked immunosorbent assays in 14 adults with untreated coeliac disease and in 10 disease controls selected because of raised total IgG activities. The untreated coeliacs showed somewhat higher total IgG activity (p approximately 0.05) and significantly raised IgA and IgG1 + IgG3 activities to gliadin but reduced IgG4 activity (p less than 0.02) compared with the controls. High IgA and IgG1 + IgG3 activities were positively correlated (r = 0.67, p less than 0.01), and so were IgG and IgG4 activities (r = 0.64, p less than 0.02). Conversely, a high IgG2 response to gliadin appeared related to a low IgA response (r = 0.55, p less than 0.05). The IgG2 response was most prominent to oat flour antigens, followed by IgG1; and the main response to soy antigens resided in IgG1, followed by IgG2 in both disease groups. There was no difference in antibody activities to oat and soy between the two groups, and raised activity to bovine serum albumin was seldom encountered. The IgA activity to alpha-lactalbumin and ovalbumin tended to be increased in the coeliacs compared with the controls. The IgG4 subclass dominated the IgG response to beta-lactoglobulin and ovalbumin and was often raised to alpha-lactalbumin, especially in the disease controls. The IgG subclass pattern to casein parallelled that to gliadin with dominance of the IgG1- and IgG3-subclass activities, especially in the coeliacs. The phlogistic potential of a response in these two subclasses might be relevant to the pathogenesis of coeliac disease and could contribute to a raised IgA gliadin response by increasing mucosal permeability. IgA activity seemed to be highest against antigens usually involved in IgE mediated food allergy.

Gut. 1992 May;33(5):632-8

Food hypersensitivity and irritable bowel syndrome.

Irritable bowel syndrome is a common condition but its pathophysiology remains poorly understood. Many irritable bowel syndrome patients give a history of food intolerance, but data from dietary elimination and re-challenge studies are inconclusive. Multiple aetio-pathological mechanisms have been postulated. The gut has an extensive immune system but current understanding of processing of food antigens in health and disease is limited. There is no clinically useful marker available to test for food hypersensitivity in irritable bowel syndrome. Researchers have employed both skin tests and serum immunoglobulins (IgG and IgE) as markers of food hypersensitivity in various disorders including irritable bowel syndrome, but published data are equivocal. In this article, the evidence for the role of food hypersensitivity in irritable bowel syndrome is reviewed and, based on the available data, a possible pathophysiological hypothesis has been formulated.

Aliment Pharmacol Ther. 2001 Apr;15(4):439-49

Food-specific IgG4 antibody-guided exclusion diet improves symptoms and rectal compliance in irritable bowel syndrome.

OBJECTIVE: Dietary modification improves symptoms in irritable bowel syndrome (IBS). Identification of offending foods by dietary elimination/re-challenge is cumbersome. IgG4 antibodies to common food antigens are elevated in IBS. The aim of this article was to evaluate the effect of exclusion diet based on IgG4 titres on IBS symptoms and rectal sensitivity and compliance. MATERIALS AND METHODS: The study comprised 25 patients with IBS (3 M, 22 F, mean age 43 years, Rome II criteria). IgG4 titres to 16 foods (milk, eggs, cheese, wheat, rice, potatoes, chicken, beef, pork, lamb, soya bean, fish, shrimps, yeast, tomatoes and peanuts) were measured. Foods with titres >250 microg/l were excluded for 6 months. Symptom severity was assessed with a previously validated questionnaire at baseline, at 3 months and at 6 months. Rectal compliance and sensitivity were measured in 12 patients at baseline and at 6 months. RESULTS: IgG4 antibodies to milk, eggs, wheat, beef, pork and lamb were commonly elevated. Significant improvement was reported in pain severity (p < 0.001), pain frequency (p = 0.034), bloating severity (p = 0.001), satisfaction with bowel habits (p = 0.004) and effect of IBS on life in general (p = 0.008) at 3 months. Symptom improvement was maintained at 6 months. Rectal compliance was significantly increased (p = 0.011) at 6 months but the thresholds for urge to defecate/discomfort were unchanged. CONCLUSIONS: Food-specific IgG4 antibody-guided exclusion diet improves symptoms in IBS and is associated with an improvement in rectal compliance.

Scand J Gastroenterol. 2005 Jul;40(7):800-7

Diagnostic tests for food allergy.

The diagnosis of food allergy is still based primarily on a detailed medical history and comprehensive physical examination. Clinical or laboratory tests only serve as an add-on tool to confirm the diagnosis. The standard techniques include skin prick testing and in-vitro testing for specific IgE-antibodies, and oral food challenges. Properly done, oral food challenges continue to be the gold standard in the diagnostic workup. Recently, unconventional diagnostic methods are increasingly used. These include food specific IgG, antigen leucocyte antibody and sublingual/intradermal provocation tests, as well as cytotoxic food and applied kinesiology and electrodermal testings. These lack scientific rationale, standardisation and reproducibility. There have been no well-designed studies to support these tests, and in fact, several authors have disproved their utility. These tests, therefore, should not be advocated in the evaluation of patients with suspected food allergy because the results do not correlate with clinical allergy and may lead to misleading advice and treatment.

Singapore Med J. 2010 Jan;51(1):4-9

Comparative study of commercial food antigen extracts for the diagnosis of food hypersensitivity.

Single lots of food allergen extracts from three different commercial sources were compared for their efficacy in evaluating immediate food hypersensitivity. Eighty-seven children with atopic dermatitis and food hypersensitivity underwent prick skin testing to a battery of 18 food extracts from each company. Results of skin tests were compared with results of double-blind, placebo-controlled oral food challenges and open challenges to determine the sensitivity, specificity, and predictive indices of each reagent. Negative predictive indices were generally good for all reagents, whereas positive predictive indices were generally poor and showed considerable variation (0% to 79%) between commercial sources. Under the conditions of the study, skin test reagents from two companies showed slightly better agreement with double-blind, placebo-controlled food challenge results than did reagents from the third company. However, with known lot-to-lot variations in extract potency and intrapatient variation in skin test results, these differences probably are not of clinical significance.

J Allergy Clin Immunol. 1988 Nov;82(5 Pt 1):718-26