Probiotics and food allergy

Castellazzi et al. Italian Journal of Pediatrics 2013, 39:47 http://www.ijponline.net/content/39/1/47 ITALIAN JOURNAL OF PEDIATRICS REVIEW Open Access Probiotics and food allergy Anna Maria Castellazzi1, Chiara Valsecchi1, Silvia Caimmi1, Amelia Licari1, Alessia Marseglia1, Maria Chiara Leoni1, Davide Caimmi1, Michele Miraglia del Giudice2, Salvatore Leonardi3*, Mario La Rosa3 and Gian Luigi Marseglia1 Abstract The exact prevalence of food allergy in the general population is unknown, but almost 12% of pediatric population refers a suspicion of food allergy. IgE mediated reactions to food are actually the best-characterized types of allergy, and they might be particularly harmful especially in children. According to the “hygiene hypothesis” low or no exposure to exogenous antigens in early life may increase the risk of allergic diseases by both delaying the development of the immune tolerance and limiting the Th2/Th1 switch. The critical role of intestinal microbiota in the development of immune tolerance improved recently the interest on probiotics, prebiotics, antioxidants, polyunsaturated fatty acid, folate and vitamins, which seem to have positive effects on the immune functions. Probiotics consist in bacteria or yeast, able to re-colonize and restore microflora symbiosis in intestinal tract. One of the most important characteristics of probiotics is their safety for human health. Thanks to their ability to adhere to intestinal epithelial cells and to modulate and stabilize the composition of gut microflora, probiotics bacteria may play an important role in the regulation of intestinal and systemic immunity. They actually seem capable of restoring the intestinal microbic equilibrium and modulating the activation of immune cells. Several studies have been recently conducted on the role of probiotics in preventing and/or treating allergic disorders, but the results are often quite contradictory, probably because of the heterogeneity of strains, the duration of therapy and the doses administered to patients. Therefore, new studies are needed in order to clarify the functions and the utility of probiotics in food allergies and ion other types of allergic disorders. Keywords: Food allergy, Probiotics, Allergic disease, Intestinal microbiota, Children Introduction Food allergy is an immunological disease that may have a high impact on the quality of life of both patients and their relatives, with economic consequences for the patients and the NHS (National Health Service). Even if the exact prevalence is not known, almost 20% of population refers several symptoms that can be related to food allergy, and most of them end up eliminating some food from the diet with a loss of nutritional balance. Such a situation may become particularly harmful especially in pediatric patients, because they might experience several clinical symptoms, but also because the restricted diet, recommended until the allergy work up is completed, could lead to possible nutritional deficiencies. In recent years many studies focused on the comprehension of molecular and immunological mechanism of * Correspondence: 3 Department of Medical and Pediatric Science, University of Catania, Catania, Italy Full list of author information is available at the end of the article allergic response and, in particular, it has been demonstrated the importance of gut microbiota for the maintenance not only of intestinal physiology, but also for the correct development of the immune system and the induction of oral tolerance. Growing evidence indicates that dietary factors as probiotics, prebiotics, antioxidants, polyunsaturated fatty acid, folate and vitamins have positive effects on the immune functions. In particular probiotic strains show the ability to restore intestinal microbic equilibrium and modulate activation of immune cells and can explain the gradually diffusion of probiotics in clinical practice and in allergy treatment. Food hypersensitivity The term “food hypersensitivity” is referred to any pathological manifestation related to food ingestion: these reactions can be mainly divided into “food intolerances” and “food allergies”, according to the molecular mechanism of action. © 2013 Castellazzi et al.; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Castellazzi et al. Italian Journal of Pediatrics 2013, 39:47 http://www.ijponline.net/content/39/1/47 IgE mediated reactions are actually the best-characterized types of allergy; non-IgE mediated reactions or cell mediated responses include those reactions in which specific cells, different from mastocytes (and basophils), are responsible for the allergic reaction, and they mostly involve the gastrointestinal tract; mixed IgE mediated and cell mediated responses are those reactions in which both IgEs and immune cells are involved [1-4]. Other pathological conditions associated with symptoms similar to food allergy include pseudo-food allergy, in which, even though the clinical picture is the same that can be detected in allergic hypersensitivities, no immunological mechanism can be demonstrated. The exact prevalence of food allergy in the general population is yet unknown. According to different metaanalysis [5,6], almost 12% of pediatric population refers a suspicion of food allergy and in Italy, about 10% of parents believe that their children suffer from food allergy [7]. However, the prevalence of food allergy is about 3% when the diagnosis is based on oral food challenge, that is the “gold standard [8,9]. Recent studies showed that, in the United States, the prevalence of food allergy is of almost 5% of children younger than 3, while the disease affects almost 4% of the adult population. Recently, Sicherer and Sampson showed a different prevalence of food allergy, stating it might interest up to 6-10% of the general population, with differences due to geographic distribution, age and ethnicity [10]. In Europe, the prevalence of food allergy is 1-2% in the adult population and 5-8% in children, even if these data are underestimated, because of the lack of good quality publications and of the different “in vitro” and “in vivo” diagnostic approaches of the different studies. Moreover, even thought the EAACI ha tried to standardize the allergy work-up for food allergies, challenges differ from one center to another, and many different specialists (pediatricians, allergists, gastroenterologists, dermatologists) seem to show different approaches to the disease. The other datum that has to be considered as clearly established, is that the prevalence of food allergy is higher during the first years of life, with an estimated incidence between 6 and 8% before the age of 2. Clinicians may therefore a (...truncated)