Diet and microbiome in the beginning of the sequence of gut inflammation

Abstract

Inflammatory bowel disease (IBD) is a chronic inflammatory condition of the gastrointestinal tract due, at least partially, to an aberrant and excessive mucosalimmune response to gut bacteria in genetically-predisposed individuals undercertain environmental factors. The incidence of IBD is rising in western and newlyindustrialized countries, paralleling the increase of westernized dietary patterns,through new antigens, epithelial function and permeability, epigenetic mechanisms(e.g., DNA methylation), and alteration of the gut microbiome.Alteration in the composition and functionality of the gut microbiome (includingbacteria, viruses and fungi) seems to be a nuclear pathogenic factor. Themicrobiome itself is dynamic, and the changes in food quality, dietary habits,living conditions and hygiene of these western societies, could interact in acomplex manner as modulators of dysbiosis, thereby influencing the activation ofimmune cells’ promoting inflammation. The microbiome produces diverse smallmolecules via several metabolic ways, with the fiber-derived short-chain fattyacids (i.e., butyrate) as main elements and having anti-inflammatory effects. Thesemetabolites and some micronutrients of the diet (i.e., vitamins, folic acid, betacarotene and trace elements) are regulators of innate and adaptive intestinalimmune homeostasis. An excessive and unhealthy consumption of sugar, animalfat and a low-vegetable and -fiber diet are risk factors for IBD appearance. Furthermore,metabolism of nutrients in intestinal epithelium and in gut microbiotais altered by inflammation, changing the demand for nutrients needed forhomeostasis. This role of food and a reduced gut microbial diversity in causingIBD might also have a prophylactic or therapeutic role for IBD. The relationship between dietary intake, symptoms, and bowel inflammation could lead to dietaryand lifestyle recommendations, including diets with abundant fruits, vegetables,olive oil and oily fish, which have anti-inflammatory effects and could preventdysbiosis and IBD. Dietary modulation and appropriate exclusion diets might be anew complementary management for treatment at disease flares and in refractorypatients, even reducing complications, hospitalizations and surgery, throughmodifying the luminal intestinal environment