ABSTRACT
Food allergy has been dened “as an adverse health effect arising from a specic immune response that occurs reproducibly on exposure to given food” (Boyce et al. 2010; Burks et al. 2012; Muraro et al. 2014a; Sampson et al. 2014). An adverse reaction to foods without any underlying immunologic mechanisms is called “nonallergic food hypersensitivity,” but those with underlying immunologic mechanisms are grouped as food allergy; food hypersensitivity is used to refer to adverse reactions to foods, regardless of whether or not immunologic mechanisms are involved (Johansson et al. 2001, 2004). Food allergy thus manifests from a sequel of immunological activities that result in intolerance of particular offending foods (Boyce et al. 2010; Burks et al. 2012; Longo et al. 2013; Muraro et al. 2014a; Sampson et al. 2014). In the majority of cases, food allergy is primarily mediated by immunoglobulin E (IgE), but some food allergies may result from aberrant cell-mediated immunity against food proteins in the absence of specic IgE antibodies (Longo et al. 2013). In the case of IgE-mediated food allergy, there is an imbalance in the T helper cell 1 (Th1)/Th2 ratio, with a skewing toward Th2, allowing for the excessive IgE production and relative deciency of Th1 (Boyce et al. 2010; Burks et al. 2012; Longo et al. 2013; Muraro et al. 2014a; Sabra et al. 2003; Sampson et al. 2014). IgE-mediated reactions to foods typically have rapid onset of symptoms after consumption of an offending food, and reactions generally involve the skin, gastrointestinal tract, cardiovascular system, and respiratory tract (Boyce et al. 2010; Burks et al. 2012; Muraro et al. 2014a; Sampson et al. 2014).Non-IgE-mediated food allergy, on the other hand, is exclusively Th1-cell-mediated activity and commonly presents with a spectrum of gastrointestinal disorders, including protein-induced enterocolitis, proctocolitis, and enteropathy syndromes, primarily affecting infants and young children (Boyce et al. 2010; Burks et al. 2012; Jyonouchi 2012; Longo et al. 2013; Muraro et al. 2014a; Sabra et al. 2003; Sampson et al. 2014). The pathogenesis of some conditions, such as eosinophilic esophagitis, eosinophilic gastroenteritis, and atopic eczema, very commonly results from processes involving both IgE-and non-IgE-mediated mechanisms
6.1 Introduction ............................................................................................................................97 6.2 Epidemiology of Food Allergy in Children and Adults .........................................................99
