Prevention and management of food allergy

The phenotypic expression and natural history of food allergy vary widely according to the patient's age, disease presentation and type of offending food. Prevention of food allergy might be achieved by altering the dietary factors responsible for the sensitization and phenotypic expression of the disease. Owing to the peculiarity of the atopic status, a minute amount of allergens can trigger both sensitization and symptoms in atopic individuals. The oral dose of β-lactoglobulin causing sensitization can be estimated to be between 1 ng and several milligrams. In food allergy, sensitization and treatment are allergen specific; therefore, for primary prevention (avoiding sensitization) and secondary prevention of food allergy (avoiding symptoms in an already sensitized subject), a product without immunogenic and allergenic epitopes should be given in each case. Babies of atopic parents are particularly prone to develop food allergy and for this reason they are called high-risk babies. Cow's milk is the most commonly offending food in both gastrointestinal and cutaneous manifestations. Cow's milk proteins are potent allergens and around 2.5% of infants experience cow's milk allergy in the first years of life. The major risk factors for cow's milk allergy are positive family history of atopy and early exposure to cow's milk proteins. Hydrolysate formulae have been developed for the purpose of reducing the allergenicity of cow's milk proteins. More recently, partially and extensively hydrolysed formulae have also been used for feeding babies with a high risk of atopy for the prevention of cow's milk allergy. However, according to the results of a recent randomized controlled study, only an extensively hydrolysated formula, and not a partially hydrolysated formula, significantly decreased the prevalence of cow's milk allergy.     

The spectrum of cow''s milk allergy

Childhood cow's milk allergy is a diagnosis encompassing various syndromes. Antigen-immunoglobulin E (IgE) antibody interaction is classically involved in mast cell degranulation in IgE-mediated food allergy, while non-IgE mediated cow's milk allergy is mostly mediated by cellular mechanisms. The diagnosis of cow's milk allergy largely relies on a good knowledge of the clinical expression of the disease. In this educational review series, we describe three cases of cow's milk allergy, first a 7-yr-old girl with persisting IgE-mediated cow's milk allergy, second a 8-month-old boy with cow's milk induced flares of atopic dermatitis, and third a 6-yr-old boy with sheep and goat milk allergy, in the absence of cow's milk allergy. The cases are discussed and summarized with more general recommendations for the clinical management of cow's milk allergy.     

Prevention and management of food allergy

The phenotypic expression and natural history of food allergy vary widely according to the patient's age, disease presentation and type of offending food. Prevention of food allergy might be achieved by altering the dietary factors responsible for the sensitization and phenotypic expression of the disease. Owing to the peculiarity of the atopic status, a minute amount of allergens can trigger both sensitization and symptoms in atopic individuals. The oral dose of beta-lactoglobulin causing sensitization can be estimated to be between 1 ng and several milligrams. In food allergy, sensitization and treatment are allergen specific; therefore, for primary prevention (avoiding sensitization) and secondary prevention of food allergy (avoiding symptoms in an already sensitized subject), a product without immunogenic and allergenic epitopes should be given in each case. Babies of atopic parents are particularly prone to develop food allergy and for this reason they are called high-risk babies. Cow's milk is the most commonly offending food in both gastrointestinal and cutaneous manifestations. Cow's milk proteins are potent allergens and around 2.5% of infants experience cow's milk allergy in the first years of life. The major risk factors for cow's milk allergy are positive family history of atopy and early exposure to cow's milk proteins. Hydrolysate formulae have been developed for the purpose of reducing the allergenicity of cow's milk proteins. More recently, partially and extensively hydrolysed formulae have also been used for feeding babies with a high risk of atopy for the prevention of cow's milk allergy. However, according to the results of a recent randomized controlled study, only an extensively hydrolysated formula, and not a partially hydrolysated formula, significantly decreased the prevalence of cow's milk allergy.     

Dietary prevention of allergic diseases in infants and small children.

The role of primary prevention of allergic disease has been a matter of debate for the last 40 years. In order to shed some light into this issue a group of experts of the Section of Pediatrics EAACI critically reviewed the existing literature on the subject. The design of observational and interventional studies was evaluated with relevance to the important factors influencing outcome of studies on allergy development/prevention. in this analysis the statements of evidence as defined by WHO were applied. Best evidence of recommendations are those fulfilling the criteria for statements category 1 and 2 and grade of recommendations A and B as proposed by WHO. This survey include target group for dietary prevention and methods and diagnostic criteria of atopic dermatitis, asthma and food allergy for prevention studies.     

Dietary prevention of allergic disease in children: Are current recommendations really based on good evidence?

We provide a critical appraisal of the literature on the effects of dietary prevention of atopic disease in children. In our view, currently available studies suffer from lack of blinding which is a major problem if the primary end point is subjective (such as the diagnosis of eczema). In addition, long-term follow-up suggests that atopic symptoms are delayed rather than truly prevented, and that only the mildest cases are prevented (or delayed). Although it has been reported that cow's milk allergy is truly prevented by dietary interventions in early life, this has never been demonstrated by double-blind placebo-controlled food challenges. No studies to date have shown effects of hypoallergenic formulae on objective markers of atopic sensitization, such as specific IgE levels. Finally, there is no universally accepted pathophysiological mechanism which could explain the usefulness of hypoallergenic formulae in allergy prevention. In conclusion, we feel that the currently available evidence on the allergy preventive effects of hypoallergenic formulae is insufficient to justify blanket advice being given to 'high risk' families. Such advice gives parents the hope that they can actually prevent allergy in their children which may not be justified. A cautious approach in advising interventions with hypoallergenic formulae to prevent allergy in high-risk infants is warranted.     

水解蛋白婴儿配方研究进展

牛奶过敏足婴幼儿最主要的食物过敏类型,1岁以内婴幼儿大约有2.5%的人群表现牛奶过敏.以天然牛奶蛋白为基础的水解蛋白配方,其变应原性降低,其中部分水解蛋白配方(pHF)可诱导口服免疫耐受,主要用于预防婴儿食物过敏和特应性皮炎;深度水解配方主要用于治疗婴儿牛奶过敏;严重牛奶过敏导致生长发育障碍的患儿,应用氨基酸配方治疗.     

Dietary prevention of allergic diseases in infants and small children

The role of primary prevention of allergic diseases has been a matter of debate for the last 40 years. In order to shed some light on this issue, a group of experts of the Section of Pediatrics EAACI reviewed critically the existing literature on the subject. An analysis of published peer-reviewed observational and interventional studies was performed following the statements of evidence as defined by WHO. The results of the analysis indicate that breastfeeding is highly recommended for all infants irrespective of atopic heredity. A dietary regimen is unequivocally effective in the prevention of allergic diseases in high-risk children. In these patients breastfeeding combined with avoidance of solid food and cow's milk for at least 4-6 months is the most effective preventive regimen. In the absence of breast milk, formulas with documented reduced allergenicity for at least 4-6 months should be used.     

Frequency of food allergy in a pediatric population from Spain

We evaluated the prevalence and characteristics of the principal foods implicated in 355 children diagnosed with IgE-mediated food allergy. Diagnosis was established on the basis of positive clinical history for the offending food, positive specific IgE by skin prick test and RAST, and open food challenge. Our results showed the principal foods involved in allergic reactions are: eggs, fish, and cow's milk. These are followed in frequency by fruits (peaches, hazelnuts and walnuts), legumes (lentils, peanuts and chick peas) and other vegetables (mainly sunflower seeds). The legumes demonstrated the highest degree of clinical cross-reactivity. Most patients with food allergy reacted to one or two foods (86.7%). Only 13.3% of patients reacted to 3 or more foods, mostly to legumes and fruits. We found that food allergy begins most frequently in the first (48.8%) and second (20.4%) years of life. Allergy to proteins of cow's milk, egg, and fish begins predominantly before the second year, demonstrating a clear relationship with the introduction of these foods into the child's diet. Allergy to foods of vegetable origin (fruits, legumes and other vegetables) begins predominantly after the second year.;     

水解蛋白配方与婴幼儿牛奶过敏的预防和治疗

食物过敏是婴幼儿最早出现的过敏问题,牛奶是婴幼儿最常见的过敏食物。牛奶过敏的临床表现多种多样,可涉及皮肤、呼吸道、消化道等多器官多系统。母乳喂养是过敏高风险婴儿的首选喂养方式,但对不能进行母乳喂养的婴儿应选择适当的低敏配方奶,水解蛋白是获得低敏配方的最好方法。根据水解的程度,水解蛋白配方分为适度水解蛋白配方和完全水解蛋白配方。完全水解配方被推荐用于牛乳蛋白过敏婴儿的治疗,适度水解配方通常推荐用于特应质高风险婴儿的初级干预。     

Soy allergy is not common in atopic children: a multicenter study

The aim of the present study was to evaluate the prevalence of soy allergy (positive skin test and positive challenge test) in a large cohort of atopic children, many of them soy fed early in life for several months. In order to investigate the prevalence of soy allergy, two groups of children were enrolled into the study. The first group comprised a cohort of 505 children with personal history suggestive of food allergy. The second group included 243 children born of atopic parents, who had been soy protein formula fed for the first six months of life for the prevention of cow's milk allergy and who had been prospectively followed up, from birth to 5 years.
As regards the prevalence of soy allergy in the cohort of children suffering from allergic disease: 31/505 children (6%) had positive skin prick test to soy, however only six of the 31 children with positive skin prick test to soy had positive challenge test to soy.
With regard to the prevalence of soy allergy in the children who had been soy protein formula fed in the first six months of life (second group): 14/ 243 children (6%) had positive skin prick test to soy, but the double blind placebo control oral food challenge to soy was positive in only one of these 14 children. In conclusion documented soy allergy is not common in atopic children.     

Dietary prevention of allergic diseases in infants and small children.

Because of scientific fraud four trials have been excluded from the original Cochrane meta-analysis on formulas containing hydrolyzed protein for prevention of allergy and food intolerance in infants. Unlike the conclusions of the revised Cochrane review the export group set up by the Section on Paediatrics, European Academy of Allergology and Clinical Immunology (SP-EAACI) do not find that the exclusion of the four trials demands a change of the previous recommendations regarding primary dietary prevention of allergic diseases. Ideally, recommendations on primary dietary prevention should be based only on the results of randomized and quasi-randomized trials (selection criteria in the Cochrane review). However, regarding breastfeeding randomization is unethical, Therefore, in the development of recommendations on dietary primary prevention, high-quality systematic reviews of high-quality cohort studies should be included in the evidence base. The study type combined with assessment of the methodological quality determines the level of evidence. In view of some methodological concerns in the Cochrane meta-analysis, particularly regarding definitions and diagnostic criteria for outcome measures and inclusion of non peer-reviewed studies/reports, a revision of the Cochrane analysis may seem warranted. Based on analysis of published peer-reviewed observational and interventional studies the results still indicate that breastfeeding is highly recommended for all infants irrespective of atopic heredity. A dietary regimen is effective in the prevention of allergic diseases in high-risk infants, particularly in early infancy regarding food allergy and eczema. The most effective dietary regimen is exclusively breastfeeding for at least 4-6 months or, in absence of breast milk, formulas with documented reduced allergenicity for at least the first 4 months, combined with avoidance of solid food and cow's milk for the first 4 months.     

Prospective, controlled, multi-center study on the effect of an amino-acid-based formula in infants with cow's milk allergy/intolerance and atopic dermatitis

Cow's milk allergy/intolerance is treated by complete avoidance of cow's milk proteins. Because cow's milk is an important food for infants, its avoidance may lead to an increased risk of growth impairment. Whilst there is evidence for the beneficial effects of extensively hydrolyzed cow's milk formulae (eHF) in infants with cow's milk allergy/intolerance, little is known about the effects of amino-acid-based formulae (AA) in such infants. We therefore performed a prospective, controlled, multi-center trial to study the efficacy of AA in comparison with eHF, on the growth and clinical symptoms of 73 infants (median age 5.7 months) with cow's milk allergy/intolerance and atopic dermatitis. Cow's milk allergy/intolerance was proven in all infants by double-blind, placebo-controlled food-challenge. We observed a significant improvement in the SCORAD index in both groups, from a mean of 24.6, at entry, to a mean of 10.7 (p < 0.0001) after 6 months. In the AA group there was a significant increase in the length standard deviation score (p < 0.04), whilst there was no difference in the eHF group. The weight-for-length values were stable in both groups. The energy intake during the study was similar in both groups. Both an AA and eHF resulted in a significant clinical improvement in infants with an early onset of symptoms of cow's milk allergy/intolerance. Feeding an AA resulted in improved growth compared with feeding eHF, despite similar dietary intakes, and may therefore be considered as a beneficial alternative in infants with severe cow's milk allergy intolerance.     

Diagnosis of food allergy in Finland:Survey of pediatric practices

Food-related symptoms are common in the first years of life, and food allergy should be diagnosed using an elimination challenge test. We surveyed Finnish hospital-based pediatricians using a self-completion questionnaire to ascertain the current clinical practice: 24 of the 25 pediatricians (representing 24 of 25 hospitals) so approached gave evaluable responses. Food allergies were diagnosed using a clinical elimination challenge test in patients with suspected allergy to cow's milk or cereals (wheat, rye, barley, oats). Of the 24 departments, four reported that they performed challenge in all patients before diagnosis was confirmed, and 14 performed challenge in most patients before diagnosis was confirmed. The duration of the challenge varied from 0.5 to 7 days (median 4 days). A 1-week challenge was used in eight hospitals. The double-blind placebo-controlled challenge was used in seven of the hospitals, and in none routinely. Altogether, 16 of the respondents agreed that there is a need to establish clinical guidelines for the diagnosis of food allergy. In conclusion, despite a long tradition of medical education on the subject of food allergy, practices vary for its diagnosis. There is therefore a requirement for appropriate clinical guidelines.     

Efficacy of donkey's milk in treating highly problematic cow's milk allergic children: An in vivo and in vitro study

Successful therapy in cow's milk protein allergy rests on completely eliminating cow's milk proteins from the child's diet: it is thus necessary to provide a replacement food. This prospective study investigated tolerance of donkey's milk in a population of 46 selected children with cow's milk protein allergy, for whom it was not possible to use any cow's milk substitute. Thirty-eight children (82.6%) liked and tolerated donkey's milk at the challenge and for the entire duration of follow-up. Catch-up growth was observed in all subjects with growth deficit during cow's milk proteins challenge. The degree of cross-reactivity of immunoglobulin E (IgE) with donkey's milk proteins was very weak and aspecific. Donkey's milk was found to be a valid alternative to both IgE-mediated and non-IgE-mediated cow's milk proteins allergy, including in terms of palatability and weight-height gain.     

Shellfish allergy in children

Food allergies affect approximately 3.5–4.0% of the world's population and can range from a mere inconvenience to a life-threatening condition. Over 90% of food allergies in childhood are caused by eight foods: cow's milk, hen's egg, soy, peanuts, tree nuts, wheat, fish, and shellfish. Shellfish allergy is known to be common and persistent in adults, and is an important cause of food induced anaphylaxis around the world for both children and adults. Most shellfish-allergic children have sensitivity to dust mite and cockroach allergens. Diagnostic cut-off levels for skin prick testing in children with shrimp allergy exist but there are no diagnostic serum-specific immunoglobulin E (IgE) values. All patients with symptoms of IgE-mediated reactions to shellfish should receive epinephrine autoinjectors, even if the initial symptoms are mild. In this study, we review three cases of clinical presentations of shellfish allergy in children.     

Food allergy as a risk factor for nutritional rickets

The case of a 14-month-old boy with vitamin D deficiency rickets as a result of unsupervised dietary manipulation in the context of cow's milk allergy is presented. Adequate supervision by a qualified dietician, coupled with appropriate supplementation, is essential if nutritional compromise is to be avoided in children with food allergy.     

Correlation between skin prick test using commercial extract of cow''s milk protein and fresh milk and food challenges

The skin prick test (SPT) is regarded as an important diagnostic measure in the diagnostic work-up of cow's milk protein allergy. It is not known whether commercial extracts have any advantage over fresh milk. The aims of the study were to (i) compare the diagnostic capacity of SPTs for the three main cow's milk proteins (alpha-lactalbumin, casein and beta-lactoglobulin) with fresh milk and (ii) determine a cut-off that discriminates between allergic and tolerant children in a controlled food challenge. A study was carried out on 104 children consecutively attending two paediatric allergy clinics for suspected cow's milk allergy. A clinical history, SPTs with fresh cow's milk and commercial extracts of its three main proteins and a challenge test were performed on all the children. A study of the validity of the prick test was also performed by taking different cut-off points for fresh milk and its proteins. Twenty-eight of 104 challenge tests (26.9%) were positive. At a cut-off point of 3 mm, fresh milk showed the greatest negative predictive value (98%), whereas casein showed the greatest positive predictive value (PPV, 85%). Calculation of 95% predicted probabilities using logistic regression revealed predictive decision points of 12 mm for lactalbumin, 9 mm for casein, 10 mm for beta-lactoglobulin and 15 mm for fresh cow's milk. We found that the greater the number of positive SPTs for milk proteins, the more likely the positive response to challenge. Having a positive SPT for all three milk proteins had PPV of 92.3% and would seem more clinically useful than any cut-off. Both fresh milk and cow's milk extract of the three main proteins could be useful in the diagnostic work-up of cow's milk allergy. Finding positivity to all three cow's milk proteins seems to be a simpler and more useful way of avoiding oral food challenges.     

Anaphylaxis to sheep's milk cheese in a child unaffected by cow's milk protein allergy

A 5-year-old atopic boy unaffected by cow's milk protein allergy experienced several anaphylactic reactions after eating food containing “pecorino” cheese made from sheep's milk. Prick-prick tests were strongly positive to sheep's buttermilk curd and `pecorino' sheep's cheese. Skin prick tests to fresh sheep's milk and to goat's milk were also positive, whereas they were negative to all cow's milk proteins, to whole pasteurized cow's milk and to cheese made from cow's milk. Specific IgE antibodies were negative to all cow's milk proteins. Conclusion Sheep's milk and cheese derived from sheep's milk may cause severe allergic reactions in children affected and, as we report, in children not affected by cow's milk protein allergy. Received: 14 January 1997 and in revised form: 20 June 1997 / Accepted: 8 July 1997     

Cows milk protein enteropathy and granulomatous duodenitis in a newborn

Cow's milk protein enteropathy is a symptom complex that composed of severe diarrhoea and malnutrition. This disorder is caused by non-immunoglobulin E-mediated food allergy. Its clinical features and natural course have been explained in many reports, of different types of cow's milk and soy reactions. In the present article, we describe a newborn patient who presented with chronic diarrhoea and failure to thrive diagnosed as cow's milk protein enteropathy. The duodenal biopsy revealed granulomatous duodenitis which has not been described before. Her clinical and pathological findings responded well to cow's milk elimination. We suggest that food allergies should be considered in differential diagnosis of patients with chronic diarrhoea and failure to thrive.     

A case of cow's milk allergy in the neonatal period-evidence for intrauterine sensitization?

Clinical manifestations of cow's milk allergy rarely occur in the first days after birth. We report on a newborn presenting with hemorrhagic mecon-ium in the first hour of life followed by bloody diarrhea in the next few days. At day 14, an elevaled total IgE, specific IgE to cow's milk and an eosinophilia in peripheral blood were found. Symptoms disappeared when the milk feed was changed to an extensively hydrolyzed casein formula. Two challenges with cow's milk formula (on day 30 and at 7 months of age) were followed by recurrence of vomiting, watery diarrhea and failure to thrive. At the age of 17 months cow's milk was tolerated well. Although other pathogenetic mechanisms cannot completely be ruled out, there is strong evidence that cow's milk allergy— induced by intrauterine sensiti-zation—explains the symptoms in our patient. In conclusion, cow's milk allergy can occur even in the first days of life, and our clinical observation supports the concept of intra-uterine sensitization to allergens.