57 Dietary Management of Atopic Eczema

Chapter 57 57 Dietary Management of Atopic Eczema C. Kugler 57.1 rioration of the skin may be observed up to 48 h after Definitions consuming the food. In addition to deterioration of the atopic eczema, simultaneous manifestations may also Adversereactionstofoodareatopicthathasincreased occur in other systems such as in the gastrointestinal in importance over the last few years. In addition to tract and the respiratory tract. toxic reactions, such as mushroom poisoning or allergy-like reactions caused by histamine (e.g., fish poisoning), these clinical pictures are differentiated as to 57.2 whether food hypersensitivity or food intolerances are Prevalence of Adverse Reaction to Food involved [25]. in Atopic Eczema Food allergies are based on immunological mechanisms, which cause patients to form allergen-specific Although food allergy is often presumed, it affects far antibodies (e.g., against cow’s milk protein), most fre- fewer patients with atopic eczema than generally quently triggered by the immediate-type, immuno- assumed. About 30% of children with atopic eczema globulin-mediated reaction [19]. may have food allergy. In adults, the figure is somewhat All other nonimmunologically triggered reactions lower. [17]. The prevalence of food allergy is correlated are assigned to food intolerances [5]. These include: with the severity of the atopic eczema: whereas there areveryfewfoodallergiestobefoundinthecaseof 1. Metabolic reaction due to an enzyme deficiency localized atopic eczema, the frequency increases in 2. Pharmacological mechanisms patients with moderate and severe atopic eczema [14]. 3. Unknown mechanisms (food idiosyncrasy). In the United States, six food allergens (hen’s eggs, Lactoseintoleranceisthemostfrequentlyoccurring cow’s milk, peanut, soya, fish, and wheat) are responsi- among the enzymatic intolerances. ble for more than 90% of the test reactions [29]. Aller- Pharmacological intolerances are shown by patients gies to food in terms of cross-reactions to pollen are afterconsumingfoodsthathaveahighcontentofbio- rarerinchildhoodbutmorecommoninadults.Typi- genic amines or of histamine-releasing substances. cal examples of cross-reactivity between foods and Food additives such as flavor enhancers or preserva- pollenareapple,birch,celery,mugwort,hazelnut,and tives (sulfites) used on foods may cause a food intoler- birch pollen [26]. Adverse reactions to food occur ance in some people. The symptoms of food intoler- rarely. ance vary and can be mistaken for those of a food allergy, i.e., they may cause a worsening of eczema in cases of patients suffering from atopic eczema. Major trig- 57.3 gers are food additives: preservatives, coloring agents, Diagnosis antioxidants, and naturally occurring ingredients [10]. Food may trigger and sustain an atopic eczema. The The diagnostic system for adverse reactions to food symptoms of an early reaction usually occur within a comprises several steps. There is no laboratory test that few minutes to 2 h [19]. Late reactions involving a dete- provides proof [21, 27]. The diagnosis is sometimes 57.4 Diagnostic Types of Diet 535 very simple if an exacerbation of the skin can be repeat- Exampleofanoligoallergenicdiet edly associated over time with a food and allergy tests Cereals: Rice support this finding. However, diagnosis is frequently Meat: Lamb, turkey difficult and time-consuming, in particular if late reac- Vegetables: Cauliflower, broccoli, zucchini tions do not provide a clear pointer to a food or if Fruits: Pear, banana adverse reactions to food are involved for which no lab- Fat: Sunflower oil, none-milk margarine Drinks: Mineral water, tea oratory test provides clear information. For this rea- Condiments: Salt, sugar son, it is necessary to undertake a step-by-step procedure that is geared to the patient in question [19]. The first and most important step in allergological diagnosis is taking the history. A clear case history may Ifthereisnoimprovementintheeczemawhilefollow- make further steps unnecessary [33]. If there are symp- ing the elimination diet, an adverse reaction to food toms that are difficult to interpret, further diagnostic appears to be improbable as a challenging factor. If procedures may be planned after an exact history [4, 5, thereisanimprovementinthesymptoms,afoodchal- 30]. lenge follows with the suspected food, under medical In addition to the history, patients should keep a supervision. diet diary. On occasions, the symptoms can be In the case of a nonspecific suspicion, an oligoanti- assigned to a particular food. The interpretation of the genic diet can be followed, using those foods that rarely records is, however, difficult because of undeclared trigger allergies in the corresponding age group and “hidden” food allergens [22]. Also, foods that are that are not conspicuous in the history. The diet com- assumed by patients (or parents) are more heavily prises approximately 15 foods that are not suspected of emphasized. triggering allergies in the case of the patient. The diet is The in vitro diagnostic system is conducted with the put together individually for each patient and carried demonstration of specific immunoglobulin in serum outforatleast10days.Thereisthenafoodchallenge (RAST). In the case of a nonspecific suspicion, the or a follow-up diet. The elimination diet comprises an allergens that are the most frequent for the age are test- oligoantigenic diet for older children, adolescents, and ed. A high specific IgE demonstrates a sensitization to adults with nonspecific suspicion of a food allergy. a food, but does not allow any conclusions to be drawn Inthecaseofbabieswhoarebeingbreast-fed,the as to a relevant allergy. As with RAST, a positive result mother (depending on the suspected and challenged in the skin prick test has the function of being only a food) should follow a corresponding elimination diet pointer to the subsequent oral challenge. It is by no before and during the oral challenge tests, since in rare means an indication for a therapeutic diet [20]. cases there may be a transfer of allergens to the child via the mother’s milk when the mother is taking food rich in allergens [30], thus falsifying the result of the 57.4 challenge. Diagnostic Types of Diet An improvement in the complaints following the elimination diet may be merely a pointer to the clinical 57.4.1 relevance of the suspected trigger. Only a subsequent Elimination Diets challenge provides the necessary confirmation. If there is a specific suspicion that one or more foods If the symptoms improve after the oligoantigenic trigger an allergy for a patient, a so-called specific diet, foods are systematically added every 2 or 3 days elimination diet (e.g., avoiding cow’s milk) is carried until the diet again corresponds to a “normal” diet and out. Babies are given a compatible formula, e.g., ex- until all foods have been identified that trigger the tensively hydrolysed formula (Nutramigen, Pregesti- adverse reaction. mil, Alfar´e) or a formula made of an amino acid mix- ture (Neocate, Pregomin AS). Allergic symptoms have also been reported after hydrolysed protein prepara- tions, extending as far as anaphylactic reactions [6, 23, 28]. 536 57 Dietary Management of Atopic Eczema 57.4.2 using skin or blood tests. Diagnostic diets are unavoid- Food Challenges able in these cases. Allergy clinics usually work togeth- 57.4.2.1 er with nutritional specialists who have experience in Double-Blind Placebo-Controlled Oral Food Challenge this field. Such nutritional specialists are able to provide patients with individual counseling and to com- The gold standard in food allergy diagnosis is the dou- pilethedietbeforesuchadrasticdietisfollowed.The ble-blind placebo-controlled food challenge (DBPCFC) pseudoallergen-poor diet [34] (without additives, [1,3,4,18,31].Theoralchallengeisintendedeitherto avoiding biogenic amines, and naturally occurring prove a food allergy so as to eliminate the food in ques- salicylic acid) is carried out over a period of approxi- tion for a certain time or to show that foods are not a mately 4 weeks and is then tested under inpatient con- challenging factor for the atopic eczema and unneces- ditions with a pseudoallergen-rich diet over at least sary dietetic restrictions can be lifted. 2 days. In the case of this challenge, it is important that Patients who have reactions to foods that can be des- as high as possible doses of the suspected food or addi- ignated with certainty as anaphylactic are usually not tives are administered since the reactions are dose- subjected to challenge testing [4]. dependent. If a patient reacts during the challenge, the Particularly in the case of time-delayed reactions, it procedure is stopped. The test substances are packaged is difficult to decide whether there is a connection and administered individually and in capsules so the between the consumption of a food and the symptoms. ingredients that have caused the reaction in the high- The DBPCFC guarantees a more objective diagnosis. pseudoallergenic diet are known. Resolution comes in 48 h, after the doctor has deter- mined whether the patient has reacted or not. 57.4.2.3 An exacerbation in the skin finding is evaluated Challenges in the Case of a Suspicion of Cross-Reaction using a standardized evaluation sheet, e.g., the SCO- to Pollen RAD [12]. Double-blind placebo-controlled challenge foods Patients who have a pollen allergy also react to food in may be administered, for example, in extensively a number of cases, since there are cross-reactive struc- hydrolysed formula. The challenging food may also be tures in both sources of allergens. The oral allergy syn- pur´eed with compatible mashed foods (e.g., mashed drome frequently occurs with oropharyngeal symp- potato) or stirred into pudding (soy pudding). A pro- toms, but there are also patients with eczema (fre- tein-freemashbasedoncarobbeanflourandricehas quently late reactions) and urticaria. The allergens are provenitsworth.Thefoodsaremaskedasrequired in many cases unstable and react to heat, i.e., some pro- with q -carotene, beet, currant, or carrot juice (if aller- cessed products may be tolerated or the symptoms do gologicallypossible).Tomatchtheflavor,aflavoring not occur so forcefully.

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