The Effect of Digestion and Digestibility on Allergenicity of Food
The Effect of Digestion and Digestibility on Allergenicity of Food(second part)
From the chapter: “Digestion of Proteins: Gastric Acid is Critical for Adequate Protein Digestion and Prevention of Food Allergy
Digestion of proteins -and therefore most food allergens- is initiated in the stomach. A low pH is essential for the inactive enzyme pepsinogen to get activated into pepsin [92]. However, if acid-suppressing drugs are given, the pH increases considerably (e.g., up to 5 with proton pump inhibitors, PPI). As shown in many previous in vitro experiments, the proper digestion by pepsin is hindered when the pH is increased (Figure 1), and this is true for a number of food proteins, like hazelnut[93], codfish [94], milk [95], and casein (Figure 1).
(A) Digestion of proteins is hampered when pH increases. Proteins, as part of the daily diet, are digested at low pH and broken down into smaller fragments, whereas a higher pH blocks proper digestion. The resulting bigger fragments or proteins are more easily recognized by the immune system, leading to an increased risk for sensitization or allergic reactions. (B) Digestion of α-casein in vitro is hampered when pH increases. Casein was readily broken down by enzymatic digestion with pepsin at pH 2.0, but remained totally intact even after 2 h of incubation with enzyme at pH 5.0. M: molecular weight marker; -: empty lane; P: pepsin; 0: no incubation time, reaction stopped immediately; “: seconds; ‘: minutes; h: hour(s); Cas: casein.
It is clear that food intake per se changes the gastric pH, which can increase from a median fasting baseline value of pH 1 to pH 4.5 with ingestion of the meal [96]. The buffer capacity thereby depends on the food composition and meal constituents. However, this effect is transient, as ongoing acid production is responsible for a subsequent decrease of the pH, which returns to ca. pH 1 about 260 min after the start of the meal [96]. Applying acid-suppressing substances can disturb this process and induce a long-lasting elevation of the gastric pH up to 5.0 [97]. In a number of food animal models, the effect of this pH-elevation was shown in vivo, as feeding digestion-labile antigen under concomitant acid-suppression resulted in a clear Th2-response and allergy symptoms [98,99,100,101,102,103,104]. This acquired sensitization capacity was true for different proteins, like codfish, hazelnut or ovalbumin, and even oral drugs, in the mouse model [99] and also in humans [105]. Importantly, several types of acid-suppressing or -neutralizing medication, like base powder [106], sucralfate [102], H2-receptor blockers [107] and proton pump inhibitors [101] produced this effect. The outcome of the immune response may depend on timing of the anti-acid drug application in relation to food uptake, and on the dosage of the antigen [101,108]. Gastric acid suppression might further impact on intestinal pH levels and consequently on protein digestion in the intestine [109]. This assumption, however, requires further investigations in clinical settings.” “The Effect of Digestion and Digestibility on Allergenicity of Food Isabella Pali-Scholl, Eva Untersmayr, Martina Klems and Erika Jensen-Jarolim. Published: 21 August 2018 Nutrients.”
The effect of digestion and digestibily on allergenicity of food (First part)
Deepening
The Effect of Digestion and Digestibility on Allergenicity of Food
ATI (Amylase/trypsin-inhibitors) Second part
Anti nutritional factors in cereals, especially amylase trypsin inhibitors, affecting digestibility.
“Anti nutritional factors (ANF) play an important role in cereals to protect against infestation and animal consumption. From an agronomic point of view these pest barriers are beneficial as the required pest control measures (chemical pesticides, storage facilities) is relatively limited.
From a health point of view a large group of ANF, the ATI are of special interest as they may impact digestion in multiple ways, e.g. they:
• can reduce digestibility of food directly by inhibition of enzymes from the digestive tract (human and microbiome; Weegels 1994),
• can increase the load of allergenic peptide presented to the small intestine, thus increasing the allergenic and inflammation reactions (Junker et al. 2012; Zevallos et al 2014)
• complexation behavior may strongly interact with the small intestine epithelium that can cause inflammation by itself (Zevallos et al 2014)
• are the not yet completely understood cause of Bakers asthma (asma), the major labour related allergy (Stobnicka and Górny, 2015)
• can increase the load of non digested peptides and carbohydrates especially of non-starch polysaccharides (FODMAPS) that are a major cause of Irritable Bowel Syndrome (IBS) which affects 7% to 21% of the general population (Chey et al 2015)
• may impact the microbiome itself. This is not established in detail
From a food processing point of view ATI’s play a negative role as they inhibit enzymes that are added as processing aids for improved processing and bread quality. This reduces processing effectiveness and quality control of cereal based products. Understanding the role of ATI in cereals food processing and food digestion and mitigation of the negative effects is therefor of prime importance for food safety, security (1) and sustainability. An interesting way to mitigate the effect of ATI could be by altering its molecular structure that is stabilised by the large number of disulphide bonds (5-6 on ca. 14 kDa; Buchanan et al 1997)”. “https://www.wur.nl/en/Research-Results/Chair-groups/Agrotechnology-and-Food-Sciences/Laboratory-of-Food-Chemistry/Research/Themes/Technology-of-cereal-foods-digestibility.htm”
Note
(1). “food security” and “food safety”can be considered as the sides of the same coin, two complementary terms that indicate, respectively, the economic and social security of having enough food to live (“food security”) and the hygienic-sanitary need to consume healthy food and water drinking (“food safety”).
The Effect of Digestion and Digestibility on Allergenicity of Food (first part)
“Abstract: Food allergy prevalence numbers are still on the rise. Apart from environmental influences, dietary habits, food availability and life-style factors, medication could also play a role. For immune tolerance of food, several contributing factors ensure that dietary compounds are immunologically ignored and serve only as source for energy and nutrient supply. Functional digestion along the gastrointestinal tract is essential for the molecular breakdown and a prerequisite for appropriate uptake in the intestine. Digestion and digestibility of carbohydrates and proteins thus critically affect the risk of food allergy development. In this review, we highlight the influence of amylases, gastric acid- and trypsin-inhibitors, as well as of food processing in the context of food allergenicity.
Omissis…..Furthermore, digestion and digestibility could determine whether food proteins are tolerated or become sensitizing agents. This aspect has therefore even been taken up by the European Food Safety Agency in their scientific opinion about evaluation of allergenicity of food and feed proteins. Higher resistance to digestion or survival along the digestive tract seems to increase the sensitization capacity of a food component and renders it more immunogenic and/or allergenic. Based on this scientific background, the present review article highlights factors influencing protein digestion and digestibility.
From the study:
Digestion of Carbohydrates: Amylase Action Critical for Starch Digestion and Microbiome
……..Omissis. Starch is digested by specific enzymes, i.e., amylases, which cleave the α-1,4-glucosidic bond of its major compound amylose, as well as the α-1,6-glucosidic bond of the second major constituent, amylopectin [15].
….. Omissis. In humans, α-amylase is a product of the exocrine pancreas. Animal models suggest that microbial amylases could be supplied in pancreas insufficiency [18]. It is not known whether this will be linked to a risk for sensitization, but α-amylase per se when inhaled is a well-known occupational allergen. In baker’s asthma associated with the flour processing industry, allergenic amylase derives from contaminating fungi [19]. In mammals, amylase is also secreted into the saliva. Its role in starch digestion has been questioned due to its low amount relative to the overall amylase activity [20]. However, in vitro studies strongly propose that salivary amylolytic activity hydrolyzes up to 80% of bread starch in the first 30 min of gastric digestion, independent of acidification by the gastric juices [21]. This critically affects the quality of remnants reaching the intestine, which will affect the composition of the microflora (discussed below).
………Omissis. The amylase action on rapidly digestible starch (RDS) renders smaller products, like disaccharides and trisaccharides [25]. These are then further hydrolyzed to glucose by other enzymes, such as α-glucosidase in the small intestine [26]. However, both amylase and α-glucosidase may act synergistically. Some compounds represent slow-digestible starch (SDS), or resistant starch (RS) as larger leftovers, which persist the gastrointestinal transit to a large degree. Usually, resulting levels of malto-oligosaccharide indicate the degree of granular starch breakdown. The starch breakdown by amylases is largely influenced by the composition of the food processing and matrix composition. Cooking has been shown to enhance the amylase breakdown of starch [27], which also depended on the individual α-amylase activity. Flavonoids are important plant constituents, which interfere with amylase activity by hydrophobic interaction in the food matrix or by formation of covalent bonds during cooking or in gastric juice, and therefore impair starch digestion [28]. This opens up potential intervention strategies in diabetic patients to decrease the fermentation speed of starch and thereby inhibit an undesired fast release of glucose. Starch may also form complexes with lipids in the food matrix, e.g., complex formation with palm oil interfered with the digestion of rice starches [29]. Interestingly, some fresh food may neutralize amylases by proteolysis. Kiwi contains actinidin, a cysteine proteinase, which specifically attacks amylase and thereby may inhibit starch digestion [30]. This may affect the presentation of allergenic epitopes in the food matrix. Amylase in the duodenum also plays a key role in the breakdown of gluten and may therefore modulate its pathophysiologic role in celiac disease [31]. While starch forms complexes with gluten during baking of bread, amylase resolves them and makes gluten accessible for thorough protein digestion. Wheat on the other hand contains anti-enzymes, such as the ATIs (amylase-trypsin inhibitors) with a role in non-celiac gluten sensitivity (NCGS) [32]. Nutritional ATIs additionally stimulate the innate immune reaction via TLR4 [32] and thereby exacerbate allergic inflammation not only in the intestine, but also in the airways in mouse models [33,34]. It is hypothesized that industrial food processing contributes to the increased numbers of non-celiac gluten/wheat sensitivity by stabilizing e.g., starch-gluten complexes, thereby bypassing the salivary and pancreatic enzymes, leaving the digestion to mucosal amylases [35]”. “The Effect of Digestion and Digestibility on Allergenicity of Food Isabella Pali-Scholl, Eva Untersmayr, Martina Klems and Erika Jensen-Jarolim. Published: 21 August 2018 Nutrients.”