L’effetto della digestione e della digeribilità sull’allergenicità degli alimenti (prima parte)
“Riassunto: ….Omissis La digestione lungo il tratto gastrointestinale è essenziale per la disgregazione dei carboidrati e delle proteine ed è un prerequisito per un adeguato assorbimento nell’intestino dei loro componenti. La digestione e la digeribilità di carboidrati e proteine influenzano quindi in modo critico il rischio di sviluppo di allergie alimentari. In questa recensione, mettiamo in evidenza l’influenza di amilasi, degli inibitori dell’acido gastrico e della tripsina, nonché della trasformazione degli alimenti nel contesto dell’allergenicità alimentare.
Omissis… .. Inoltre, la digestione e la digeribilità potrebbero determinare se le proteine alimentari sono tollerate o diventano agenti sensibilizzanti. Questo aspetto è stato evidenziato dall’Agenzia europea per la sicurezza alimentare parere scientifico sulla valutazione dell’allergenicità delle proteine alimentari e dei mangimi. Una maggiore resistenza alla digestione o alla sopravvivenza lungo il tratto digestivo sembra aumentare la capacità di sensibilizzazione di un componente alimentare e renderlo più immunogenico e / o allergenico. Sulla base di questo background scientifico, questo articolo di recensione evidenzia i fattori che influenzano la digestione e la digeribilità delle proteine.
Estratto dallo studio:
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 .
….. Omissis. In humans, α-amylase is a product of the exocrine pancreas. Animal models suggest that microbial amylases could be supplied in pancreas insufﬁciency . 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 . 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 . 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 . 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 . These are then further hydrolyzed to glucose by other enzymes, such as α-glucosidase in the small intestine . 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 , 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 . 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 . 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 . 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 . 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) . Nutritional ATIs additionally stimulate the innate immune reaction via TLR4  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 ”. “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.”