E. Celiac Foods of Concern Celiac disease is caused by an immune response in genetically predisposed individuals to specific storage proteins, commonly referred to as “glutens,” that occur naturally in cereal grains (Shan et al., 2002). Technically, “gluten” is a term applied specifically to the combination of the prolamin proteins called “gliadins” and the glutelin proteins called “glutenins” found in wheat (Brown, 2004). However, the term “gluten” has been used generically to refer to prolamin and glutelin protein mixtures found in other cereal grains (Kasarda, 2005, personal communication). Although all cereal grains contain prolamin and glutelin proteins, these proteins are not identical in different grains. These proteins differ in their amino acid sequences in different grains, and not all have been shown to evoke an abnormal immune response that affects the intestinal lining of persons genetically susceptible to celiac disease (Kasarda, 2003). The term “gluten” will be used in this report in the more general sense of the combination of both prolamin and glutelin proteins found in cereal grains.
The grains considered to be capable of producing adverse effects in individuals with celiac disease include the different species of wheat (e.g., durum, spelt, kamut), barley, rye, and their cross-bred hybrids (e.g., triticale, which is a genetic cross between wheat and rye) (Kasarda, 1994; Kasarda, 2004). There is also evidence that some individuals with celiac disease may react adversely to oats (Lundin et al., 2003; Arentz-Hansen, 2004). These grains are all members of the grass family (Gramineae, also known as Poaceae) and are closely related taxonomically. The cereal grains assumed to be safe for persons with celiac disease include amaranth, buckwheat, corn, Indian ricegrass, Job’s tears, millet, quinoa, ragi, rice, sorghum, teff (or tef), and wild rice (Kasarda, 2001; Johnson et al., 2002; Kasarda, 2004b; Kupper, 2004).
The grain prolamins of concern include gliadin in wheat, secalin in rye, hordein in barley (Thompson, 2001; Green and Jabri, 2003; Kagnoff, 2005) and possibly avenin in oats (Arentz-Hansen, et al. 2004; Lundin, et al., 2003). There is substantial evidence that both prolamin proteins (i.e., gliadins) and glutelin proteins (i.e., glutenins) in wheat affect individuals with celiac disease (Shan et al., 2002; Hausch et al., 2002; Vader et al., 2002; van de Wal et al., 1999; Molberg et al., 2003).
Wheat gliadin subtypes alpha, beta, gamma, and omega, have been shown to affect individuals with celiac disease (Ciclitira et al., 1984; EFSA, 2004). Rye, barley and triticale are taxonomically related to wheat, express peptides structurally similar to those found in wheat, and have been reported to affect individuals with celiac disease (Vader et al., 2002; Kasarda, 2001; Kasarda, 2004b). In contrast, the prolamins in other cereal grains (e.g., zein in corn and orzenin in rice) have been shown not to affect individuals with celiac disease (EFSA, 2004; Kasarda, 2004b). However, much is still unknown about which proteins in the different grains can affect individuals with celiac disease (Kasarda, 2001).
Analytical information is not available on the actual amount of gluten proteins in different grain-derived food ingredients or finished foods. For single ingredient foods made from wheat, rye, barley, triticale, and oats, the simple presence of “protein” in that
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