Food Elimination Diet Research Articles

Responses of dogs with food allergies to single-ingredient dietary provocation

Objective To characterize specific food ingredients causing allergic reactions in dogs and to assess cross-reactivity between proteins derived from a single animal source or from different plant products. Design Prospective study. Animals 25 dogs with histories and cutaneous signs consistent with food-allergic dermatitis. Procedure Dogs were fed a food-elimination diet until resolution of clinical signs and then challenged with their original diet. A diagnosis of food allergy was made if there was complete return of pruritus within 14 days of challenge exposure. After diagnosis, dogs were fed the food-elimination diet until signs related to dietary challenge abated. The dogs then were fed beef, chicken, chicken eggs, cows' milk, wheat, soy, and corn in single-ingredient provocation trials for 1 week. Any cutaneous reactions to these food ingredients were recorded by their owners. Results Beef and soy most often caused adverse cutaneous reactions, although all ingredients induced clinical signs in at least 1 dog. Mean number of allergens per dog was 2.4, with 80% reacting to 1 or 2 proteins and 64 % reacting to 2 or more of the proteins tested. A significant difference was found between dogs reacting to beef versus cows' milk and between dogs reacting to soy versus wheat; thus, the hypothesis of cross-reactivity to ingredients derived from a single animal source or to different plant products was not supported. Similar differences between chicken meat and eggs were not identified. Clinical Implications Long-term management of dogs with food allergies is facilitated by identification of the most commonly encountered food allergens. Because cross-reactivity cannot be verified, each protein source should be included separately in food-provocation trials. (J Am Vet Med Assoc 1996;209:608-11)

Food immediate-contact hypersensitivity (FICH) and elimination diet in young children with atopic dermatitis. Preliminary results in 107 children.

In atopic dermatitis [AD], not only food consumption, but direct skin-contact too can provoke hypersensitivity reactions. We imitated food immediate-contact hypersensitivity [FICH] to cow's milk, egg, peanut or soy by a skin provocation test. This skin application food test [SAFT] was applied in 91 patients aged up to 5 years and suffering from AD, and in 16 healthy controls (all SAFT-negative). In the SAFT-positive patients (n = 61), FICH to egg was observed in 72%, to cow's milk in 47%, to peanut in 34% and soy in only 1 patient. SAFT and RAST scores correlated weakly. Nevertheless, many discrepancies between SAFT and RAST results were found. In 20 of the 61 (33%) patients with FICH, a flare-up in AD was noted at SAFT testing. Upon introducing dietary restrictions, AD improved impressively in 9 of 23 patients who could be followed up. FICH is an important symptom in children with AD and food allergy.

Children with Atopic Eczema. II: Immunological Findings Associated with Dietary Manipulations

A group of 91 children with atopic eczema entered a study where clinical and immunological features were compared before and after a food elimination diet, and after double blind randomized food challenges in which a food was given for several days at a time. Eczema improved significantly during the diet and became worse on food challenges. The clinical outcome of food elimination could not be predicted by the initial skin prick test results, serum immunoglobulins, total or food-specific IgE, or complexed IgG or IgE. There was a tendency for patients whose eczema did not improve after food elimination to have higher initial serum IgG levels, without a corresponding increase in skin infections. The radioallergosorbent test to soy gave a higher result in those who improved on diet. No significant changes in serum or complexed immunoglobulins occurred over the period of food elimination or subsequent food challenge. Results of food challenges could not be predicted by initial serum immunoglobulin levels. A history of spring/summer exacerbations of eczema correlated with positive skin prick tests to silver birch pollen, but not to grass pollen. Serological tests did not help in planning food diets in atopic eczema, and the immunological studies did not delineate any particular mechanism by which foods might exacerbate eczema.

Children with Atopic Eczema. I: Clinical Response to Food Elimination and Subsequent Double-blind Food Challenge

The role of foods in the exacerbation of atopic eczema was studied by offering a food elimination diet and subsequent random order, double-blind food challenges to 91 eczematous patients, [49 males and 42 females, median age 4.5 years (range 0.5-15)]. Eczema improved in 49 of 66 (74 per cent) (skin score fall greater than or equal to 3) after stopping cows' milk, eggs and various other foods, with significant decreases in erythema, excoriation, lichenification and extent of eczema. One hundred and ninety-four food challenges were given to 64 patients who had shown objective or subjective improvement. Eczema and associated symptoms were significantly worse after cows' milk and tomato compared with placebo. Egg did not worsen eczema, but 48 per cent of 44 challenges were incomplete, mainly due to hypersensitivity reactions and challenge refusal. The longer a food had been avoided, the less likely was the chance of a positive food reaction. Clinical history did not predict response to dietary manipulation. A standard elimination diet avoiding cows' milk, egg, tomatoes and possibly colours and preservatives should help up to three-quarters of patients, and is easy to implement with the help of a dietician. This diet may be considered in all children with moderate or severe eczema.

Diagnostic testing of dogs for food hypersensitivity

Summary Thirteen food-allergic dogs were studied to evaluate the efficacy of feeding a commercially available egg and rice diet, intradermal skin testing, and serologic testing by elisa for diagnosing and/or characterizing food hypersensitivity. Feeding of a home-cooked whole lamb meat and rice diet for 3 weeks, followed by challenge with each dog's regular diet, served as the standard for diagnosing food hypersensitivity. Each dog underwent provocative testing with 6 individual ingredients to determine as many of its dietary allergens as possible. Prior to skin testing and serologic testing by elisa, most dogs had been recently exposed to the offending diet and subsequently manifested clinical signs of allergy. All dogs that tolerated the aforementioned commercial diet were exposed to it for at least 7 weeks; 84.6% of food-hypersensitive dogs ate the commercial diet with impunity. Of the 2 reactors to the commercial diet, only 1 became pruritic in response to provocation testing with chicken eggs. Low sensitivity and high specificity were found for skin testing and the elisa, indicating a lack of true- and false-positive reactions. Neither the positive nor negative predictive values adequately predicted positive and negative reactions, respectively, for either test. On the basis of these results, the commercial diet, skin testing, and anti-IgE elisa cannot replace an owner-prepared food elimination diet for food hypersensitivity testing in dogs.

Allergy Management of Refractory Serous Otitis Media

Twenty patients classified as having otitis media with effusion (OME) refractory to all previous medical and surgical therapy were entered into a prospective study to see if classic allergy techniques could diagnose and treat otherwise unresolved effusion and persistent hearing loss in lieu of the re-insertion of tympanostomy tubes. RAST testing, skin end point titration and food elimination diets identified a possible allergic etiology in all patients. Among those choosing allergy immunotherapy, 65% maintained normal hearing, normal tympanograms, and the elimination of recurrent infections for three years. The remaining 35% resolved on appropriate food elimination diets. None of the control's symptoms resolved. The history of chronic disease is defined. The pathophysiology of allergic mechanisms and studies attempting to prove or disprove an allergic effect on the middle ear and eustachian tube are reviewed.

Placebo-controlled double-blind food challenge in asthma

To determine the prevalence of food allergy as a cause of exacerbation of asthma, we studied 300 consecutive patients with asthma (7 months to 80 years of age) who attended a respiratory clinic. Each patient was screened for possible food allergy by means of a questionnaire and by skin prick tests with the six food allergens most common in our area. Patients with either a suggestive history and/or a positive prick test and/or RAST underwent double-blind food challenge with lyophilized food in capsules or food mixed in a broth to disguise its taste. Pulmonary function tests and symptoms were followed for 8 hours after each challenge. Of the 300 patients screened, only 25 had either a history or skin prick tests or RAST responses suggestive of food allergy. Twenty patients had interpretable food challenges. In these 20 patients, food challenge caused asthma in six and caused other symptoms (atopic dermatitis and gastrointestinal symptoms) in five. On rechallenge after pretreatment with disodium cromoglycate (300 mg 30 minutes before the food challenge), the asthmatic response was blocked in four of five subjects. The patients with asthma with food allergy were generally young, had a current or past history of atopic dermatitis, and high total serum IgE levels. Our findings confirm that food allergy can elicit asthma, but its incidence is low, even in the population attending a specialty clinic. Food elimination diets should not be prescribed for all patients reporting an adverse reaction to foods or having a positive skin prick test and/or RAST with food allergens. In patients with asthma caused by food allergy, disodium cromoglycate may be used to complement elimination diets.