Gluten is a structural protein naturally found in certain cereal grains. The term gluten generally refers to the prolamins of wheat grain, specifically glutelin proteins, that naturally occur in many cereal grains and can trigger celiac disease in some people. Studies indicate that celiac disease is an immune response to the ingestion of gluten in genetically predisposed individuals, resulting in inflammation and damage to the mucosa of the small intestine. The incidence of celiac disease is around 1% of the global population, but many people remain undiagnosed due to the variability of symptoms.
The types of grains that contain gluten include all species of wheat (common wheat, durum, spelt, khorasan, emmer, and einkorn), as well as barley, rye, and some cultivars of oat; moreover, cross hybrids of any of these cereal grains also contain gluten, such as triticale. Gluten makes up 75-85% of the total protein in bread wheat. Studies on gluten digestion reveal that its incomplete digestion in the human gastrointestinal tract can lead to the formation of proteolysis-resistant peptides, which can trigger immune responses in people with celiac disease.
Glutens, especially Triticeae glutens, have unique viscoelastic and adhesive properties, which give dough its elasticity, helping it rise and keep its shape, often leaving the final product with a chewy texture. These properties, and its relatively low cost, make gluten valuable to both food and non-food industries. Wieser's research (2007) highlights that the functional properties of gluten are crucial for the quality of bread and other baked goods. Additionally, gluten proteins can be used in bioplastics and other industrial materials due to their adhesive properties.
Wheat gluten is composed mainly of two types of proteins: the glutenins and the gliadins, which, in turn, can be divided into high molecular weight and low molecular weight glutenins, and α/β, γ, and Ω gliadins. Its homologous seed storage proteins, in barley, are referred to as hordeins, in rye, secalins, and in oats, avenins. These protein classes are collectively referred to as "gluten." Storage proteins in other grains, such as maize (zeins) and rice (rice protein), are sometimes called gluten but do not cause harmful effects in people with celiac disease. Furthermore, research suggests that oat avenins are less immunogenic than the prolamins of wheat, barley, and rye, allowing some people with celiac disease to consume oats without adverse symptoms.
Bread produced from wheat grains contains gluten.
Gluten can trigger adverse, inflammatory, immunological, and autoimmune reactions in some people. The spectrum of gluten-related disorders includes celiac disease in 1–2% of the general population, non-celiac gluten sensitivity in 0.5–13% of the general population, as well as dermatitis herpetiformis, gluten ataxia, and other neurological disorders. These disorders are treated with a gluten-free diet.
Research in functional nutrition indicates that chronic inflammation caused by gluten can lead to a range of adverse health conditions. Inflammation is a natural biological response of the body to injury or infection, but continuous exposure to gluten can cause persistent inflammation in the gastrointestinal tract and other systems of the body. This chronic inflammation is associated with an increased risk of developing autoimmune diseases, including type 1 diabetes and thyroid diseases.
Additionally, non-celiac gluten sensitivity (NCGS) is an emerging condition characterized by intestinal and extraintestinal symptoms related to gluten consumption in the absence of autoimmune markers characteristic of celiac disease. Studies show that NCGS may be associated with an innate immune response to gluten, differing from the adaptive response observed in celiac disease.
An important aspect of functional nutrition is the role of diet in modulating inflammation. Anti-inflammatory diets, which include foods rich in antioxidants, omega-3 fatty acids, and fiber, can help reduce systemic inflammation. Foods such as fatty fish, nuts, seeds, fruits, and vegetables are essential components of these diets. Excluding gluten can be a fundamental part of these dietary strategies for individuals sensitive to gluten or with gluten-related diseases.
Adhering to a gluten-free diet can also improve gut health and the microbiome. Studies show that a gluten-free diet can promote microbial diversity in the gut, which is beneficial for digestive and immune health. However, it is important to ensure that the gluten-free diet is balanced and nutrient-rich, as excluding traditional grains can lead to nutritional deficiencies if not well planned.
References:
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