Adverse Reactions to Wheat or Wheat Components

Abstract

Wheat is an important staple food globally, providing a significant contribution to daily energy, fiber, and micronutrient intake. Observational evidence for health impacts of consuming more whole grains, among which wheat is a major contributor, points to significant risk reduction for diabetes, cardiovascular disease, and colon cancer. However, specific wheat components may also elicit adverse physical reactions in susceptible individuals such as celiac disease (CD) and wheat allergy (WA). Recently, broad coverage in the popular and social media has suggested that wheat consumption leads to a wide range of adverse health effects. This has motivated many consumers to avoid or reduce their consumption of foods that contain wheat/gluten, despite the absence of diagnosed CD or WA, raising questions about underlying mechanisms and possible nocebo effects. However, recent studies did show that some individuals may suffer from adverse reactions in absence of CD and WA. This condition is called non‐celiac gluten sensitivity (NCGS) or non‐celiac wheat sensitivity (NCWS). In addition to gluten, wheat and derived products contain many other components which may trigger symptoms, including inhibitors of α‐amylase and trypsin (ATIs), lectins, and rapidly fermentable carbohydrates (FODMAPs). Furthermore, the way in which foods are being processed, such as the use of yeast or sourdough fermentation, fermentation time and baking conditions, may also affect the presence and bioactivity of these components. The present review systematically describes the characteristics of wheat‐related intolerances, including their etiology, prevalence, the components responsible, diagnosis, and strategies to reduce adverse reactions.

Wheat Seed Proteins: Factors Influencing Their Content, Composition, and Technological Properties, and Strategies to Reduce Adverse Reactions

“…The repetitive domains determine the solubility properties of the gliadins and glutenin subunits and also result in the unusual amino acid compositions of the whole proteins: notably, glutamine (Q) accounts for between 30% and 50% of the total amino acid residues (the proportion relating to the extent of the repetitive domains and their peptide motifs). The numbers of glutamine residues and their sequence contexts also define the ability of gluten proteins to elicit a response in coeliac disease, as discussed in the associated article (Brouns, Van Rooy, Shewry, Rustgi, & Jonkers, ––accompanying review).…”

“…These studies showed that certain putative “ancient” tetraploid wheat types, such as Graziella Ra, Khorasan, and Kamut wheats, have even higher amounts of total gliadin than modern accessions of tetraploid pasta wheat (Brouns et al., ; Brouns, Van Rooy, Shewry, Rustgi, & Jonkers, ; Colomba & Gregorini, , accompanying review) and are therefore unsuitable for coeliac patients (Gregorini, Colomba, Ellis, & Ciclitira, ; Shewry, ). Furthermore, whereas Pizzuti et al.…”

“…In theory, any gluten peptide comprising more than nine amino acids can potentially elicit an immune reaction in susceptible individuals (Osorio et al, 2012). Since no wheat genotypes are entirely gluten-free, no recent or old wheat varieties, landraces, or related diploid and tetraploid species or progenitors can be considered "coeliac-safe" (Brouns, Van Rooy, Shewry, Rustgi, & Jonkers, 2019;Brouns, van Buul, & Shewry, 2013;Goryunova et al, 2012;Mitea et al, 2010;Shewry, 2018--accompanying review). Support for this conclusion comes from wide genetic screens of wheat and related species for their immunogenic potential.…”

“…These studies showed that certain putative "ancient" tetraploid wheat types, such as Graziella Ra, Khorasan, and Kamut wheats, have even higher amounts of total gliadin than modern accessions of tetraploid pasta wheat (Brouns et al, 2013;Brouns, Van Rooy, Shewry, Rustgi, & Jonkers, 2019;Colomba & Gregorini, 2012, accompanying review) and are therefore unsuitable for coeliac patients (Gregorini, Colomba, Ellis, & Ciclitira, 2009;Shewry, 2018). Furthermore, whereas Pizzuti et al (2006) proposed that diploid einkorn wheat (Triticum monococcum) is nontoxic for coeliac patients, this was based on limited data and later studies revealed that it is not suitable (Gianfrani et al, 2012) (Table 1; Kasarda, 2007;Vaccino, Becker, Brandolini, Salamini, & Kilian, 2009).…”

“…The etiology, prevalence, diagnosis, and treatment of these conditions are discussed in the accompanying review in this journal, entitled: “Adverse reactions to wheat or wheat components” (Brouns, Van Rooy, Shewry, Rustgi, & Jonkers, ). However, to understand and evaluate the evidence for the role of wheat proteins in determining these conditions, and strategies for ameliorating them, it is necessary to provide an account of the putative causative proteins, focusing on features relevant to their activity.…”